Calibrating the self-thinning frontier

Forest Ecology and Management doi: 10.1016/j.foreco.2009.09.045

Calibration of the self-thinning frontier in even-aged monocultures is hampered by scarce data and by subjective decisions about the proximity of data to the frontier. We present a simple model that applies to observations of the full trajectory of stand mean diameter across a range of densities not close to the frontier. Development of the model is based on a consideration of the slope s=ln(Nt/Nt 1)/ln(Dt/Dt 1) of a log-transformed plot of stocking Nt and mean stem diameter Dt at time t. This avoids the need for subjective decisions about limiting density and allows the use of abundant data further from the self-thinning frontier. The model can be solved analytically and yields equations for the stocking and the stand basal area as an explicit function of stem diameter. It predicts that self-thinning may be regulated by the maximum basal area with a slope of -2. The significance of other predictor variables offers an effective test of competing self-thinning theories such Yoda's -3/2 power rule and Reineke's stand density index.

Tree diameter, height and stocking in even-aged forests

Annals of Forest Science 66:702 (2009)

Empirical observations suggest that in pure even-aged forests, the mean diameter of forest trees (D, diameter at breast height, 1.3 m above ground) tends to remain a constant proportion of stand height (H, average height of the largest trees in a stand) divided by the logarithm of stand density (N, number of trees per hectare): D = beta (H-1.3)/Ln(N). Thinning causes a relatively small and temporary change in the slope beta, the magnitude and duration of which depends on the nature of the thinning. This relationship may provide a robust predictor of growth in situations where scarce data and resources preclude more sophisticated modelling approaches.

Managing water use from forest plantations

Forest Ecology and Management 257:385-389 (2009)

Tree plantations have developed a reputation for excessive water use, with age commonly used as an explanatory variable to predict water loss – but many factors have the potential to affect plantation water use, and few of these alternatives have been considered. Changes in forest cover may be correlated with other environmental changes that may affect precipitation, transpiration, and runoff, indicating that more thorough investigation is required in both field and simulation studies. Several factors influencing water use by plantations are amenable to management control, so there is scope to design and manage forest plantations deliberately for water use efficiency. Research is needed to elucidate the relative contributions of forests and grasslands to atmospheric moisture; the influence of vegetation on the distribution of rainfall; the effect of air turbulence from plantation edges, firebreaks and streamlines; the potential to modify atmospheric coupling of forest plantations through plantation design, including the use of mixed species plantations, and by softening hard edges by thinning and pruning plantation edges.

Bias in the journal impact factor

Scientometrics 78:3-12 (2009)

The ISI journal impact factor (JIF) is based on a sample that may represent half the whole-of-life citations to some journals, but a small fraction (<10%) of the citations accruing to other journals. This disproportionate sampling means that the JIF provides a misleading indication of the true impact of journals, biased in favour of journals that have a rapid rather than a prolonged impact. Many journals exhibit a consistent pattern of citation accrual from year to year, so it may be possible to adjust the JIF to provide a more reliable indication of a journal's impact.

Improved Tropical Forest Management for Carbon Retention

PLOS Biology 6(7):1368-1369 (2008)

Forest site productivity: a review of the evolution of dendrometric concepts for even-aged stands

Forestry 81:13-31 (2008)

Forest site productivity is the production that can be realised at a certain site with a given genotype and a specified management regime, and depends on both natural factors inherent to the site, and on management related factors. This review of the evolution of site assessment highlights three tenets of forest site productivity: the height-age site index, Eichhorn’s rule, and the thinning response hypothesis. These tenets rely on the hypotheses that height growth correlates well with stand volume growth; that total volume production of a given tree species at a given stand height should be identical for all site classes; and that stand volume growth is independent of thinning practice for a wide range of thinning grades. The maturation of long-term field experiments has provided for the revision of these hypotheses, and contributed to an understanding of situations where they do not hold. Stand volume growth per unit of height growth has been called the yield level. The use of the yield level theory for estimating site productivity has facilitated the development of a three-dimensional model of the relationship between stem number, quadratic mean diameter and stand basal area. Given this model, a stand density index based on the combination of stem number and quadratic mean diameter provides an indication of the yield level, which may be used to adjust height-age based estimates of site productivity.

Colour variation and correlations in Eucalyptus dunnii sawnwood

Journal of Wood Science 54:431-453 (2008)

A study of material thinned from a 9-year-old Eucalyptus dunnii progeny trial revealed that E. dunnii has light yellowish wood that is relatively uniform in color, and varies little within and between trees. The variation in color between half-sib families is small, but is statistically significant (P = 0.008). Most of the color variation relates to the yellowness (CIE b*) of the wood, which in heartwood is moderately heritable (h = 0.6). The color of the endgrain, especially its lightness (CIE L*) and whiteness index (E313), is correlated with basic density, hardness, and rates of shrinkage. The CIE rectangular opponent scale (L*, a*, b*) appeared to be the most informative about wood color and properties, and no additional information was gleaned from an analysis of full spectral data in the range 400–700 nm.

Gauging the impact of journals

Forest Ecology and Management 256:507-509 (2008)

Ranking forestry journals using the h-index

Journal of Informetrics 2:326-334 (2008)

An expert ranking of forestry journals was compared with journal impact factors and h-indices computed from the ISI Web of Science and internet-based data. Citations reported by Google Scholar appear to offer the most efficient way to rank all journals objectively, in a manner consistent with other indicators. This h-index exhibited a high correlation with the journal impact factor (r=0.92), but is not confined to journals selected by any particular commercial provider. A ranking of 180 forestry journals is presented, on the basis of this index.

Genetic variation in dimensional stability of Eucalyptus pilularis (Smith) assessed using increment cores and test blocks

New Zealand Journal of Forestry Science 38:194-210 (2008)

Assessments of genetic variation in wood properties are difficult and expensive to carry out. As a consequence, the inclusion of wood quality traits in eucalypt breeding programs has to date been limited. This study is part of a large investigation into the use of non-destructive methods of assessing wood properties by comparing the results with traditional destructive methods. This component of the study investigates the genetic variation in linear shrinkage of 152 open-pollinated families of Eucalyptus pilularis (Smith). Increment cores and test blocks were used to assess radial and tangential shrinkage as well as their ratio. Shrinkage results at 17% MC, 12% MC and 5% MC are presented here. Heritability estimates were moderate for tangential shrinkage but not significant for radial shrinkage or the ratio of the two. The genetic correlation between shrinkage measured on cores and on blocks at this stage was not sufficient to justify the use of increment cores alone in genetic assessments. Basic density had a moderate and negative correlation with tangential shrinkage, suggesting that selecting for higher basic density may help reduce tangential shrinkage. The increment core method was not successful at measuring radial shrinkage due to core distortion but an improved method is suggested. Measurements from scans and blocks showed that radial shrinkage was not heritable.

Community Attitudes towards Private Native Forestry in New South Wales

Small-Scale Forestry 6:177-188 (2007)

An on-line survey during August-September 2006 examined community attitudes toward private native forestry. Survey findings (n=156) confirmed prior hypotheses that attitudes would correlate with associations (e.g., professionals in favour of incentives, farmers in favour of freedom to manage, conservationists in favour of regulations), and with interest (biodiversity enthusiasts in favour of regulations; producers in favour of incentives), but refuted the prior hypotheses that urban dwellers would be more likely to favour regulations. Respondents appear to reflect different constituencies with divergent views without a shared understanding of the condition and dynamics of these forests. This indicates the need for more extension and public education, particularly since forests continue to be an election issue. The survey does not gauge support for private native forestry, but helps to untangle the views from the constituencies promoting them. Regulatory approaches received most support from respondents affiliated with an environmental groups, with a national concern for biodiversity, who fear that private native forests are in poor condition and are going to get worse. Advocates for more landholder freedom tend to be landholders who believe that private native forests are in better condition than comparable State Forests, and who are optimistic about the future for private native forests. Advocates for incentives tend to be urban dwellers with a production focus and professional affiliations.

How to foster good husbandry of private native forests

Small-Scale Forestry 6:205-218 (2007)

It is generally agreed that effective conservation requires the cooperation of private landholders to complement reserve-based efforts, but there is little agreement about how this can best be achieved. Various stakeholders lobby for tough regulations, for greater landholder freedom, and for incentives for activities or outcomes. A review of these alternatives suggests an emerging consensus that incentives are the most effective approach. Policy-makers should consider incentive-based approaches such as stewardship support to foster conservation outcomes on private lands.

A long and winding road: the regulation of private native forestry in New South Wales, Australia

Small-scale Forestry 6:111-113 (2007)

This special issue of Small-Scale Forestry is concerned with private native forestry (PNF) in New South Wales (NSW), Australia. Private native forests comprise indigenous species in a semi-natural formation on privately owned land. Such forests are usually uneven-aged, and regenerated naturally rather than by sowing or planting. These forests are of major conservation and commercial importance in NSW, covering 8 M ha and comprising one-third of all native forest in the state (Thompson 2007). The management and harvesting of these forests is known as PNF, and has been the focus of public attention for several years, as the desirability and implications of regulating these activities has been debated.

Social and ecological issues for private native forestry in north-eastern New South Wales, Australia

Small-Scale Forestry 6:115-126 (2007)

Forests in north-eastern New South Wales have often been the focus of controversy. The tension between production and preservation continues and hampers current negotiations for a code of practice for private native forestry. The structure of many private forests reflects past mismanagement and silvicultural intervention would benefit both conservation and production objectives, but such intervention is rarely financially viable. This paper sets out the economic and ecological basis for private native forestry. Both the timber industry and nature-based tourism are major contributors to the local economy, and both rely in part on private native forests. Draft regulations currently under negotiation do not offer incentives for improved private forest management.

User Satisfaction: An Evaluation of a Carbon Credit Information System

Smart, W.J., B. Armstrong and J.K. Vanclay, 2007. User Satisfaction: An Evaluation of a Carbon Credit Information System. 18th Australasian Conference on Information Systems (ACIS 2007), 5-7 Dec 2007, Toowoomba.

This paper presents the analysis of user satisfaction with a web-based system that enables users to calculate the value of carbon credits for landholdings based on user-defined parameters including size of landholding, monoculture species, site quality, management & perpetration etc. For the purposes of this project, User Satisfaction was evaluated using questions based on the User Information Satisfaction (UIS) surveys demonstrated to validate the DeLone and McLean (1992, 2003) model of information systems success. The items in the survey used to test the UIS for this study were modified to suit the nature of the system under investigation, that is, a public, web-based information system. This differs from most previous UIS surveys which have been primarily used to examine proprietary, in-house applications. The paper reports the structural validity of the instrument using exploratory factor analysis (EFA) and structural equation modelling (SEM).

On the robustness of the h-index

Journal of the American Society for Information Science and Technologym58:1547-1550 (2007)

The h-index (Hirsch, 2005) is robust, remaining relatively unaffected by errors in the long tails of the citations-rank distribution, such as typographic errors that short-change frequently-cited papers and create bogus additional records. This robustness, and the ease with which h-indices can be verified, support the use of a Hirsch-type index over alternatives such as the journal impact factor. These merits of the h-index apply to both individuals and to journals.

Educating Australian foresters for the 21st century

International Forestry Review 9:884-891 (2007)

A review of forestry education based on literature and a survey of 186 foresters reveals the diversity of interests within the Australian forestry profession. The survey reflects the utility of subjects such as silviculture, mensuration and forest management, and highlights the need to include subjects such as human resource management, business studies and communication skills in forestry programs. Results also suggest that there is the need for more innovation in the teaching of foundation subjects such as chemistry. Important but unexpected findings from the survey were the high proportion of respondents who stated that their bachelor studies provided their formative career preparation, and the acknowledgement of the role of vacation work experience in reinforcing formal academic study.

Potential contributions of statistics and modelling to sustainable forest management: Review & synthesis

Rennolls, K., M. Tome, R.E. McRoberts, J.K. Vanclay, V. LeMay, B. Guan and G. Gertner, 2007. Potential contributions of statistics and modelling to sustainable forest management: Review & synthesis. Chapter 20 in K. Reynolds, A. Thomson, M. Shannon, M. Kohl, D. Ray and K. Rennolls (eds) Sustainable Forestry in Theory and Practice. CAB International, Wallingford.

This chapter provides a review of the statistical and modelling disciplines, their techniques and potential contribution to sustainable forest management (SFM). The main topics covered are:

Mensuration and models for sustainable forest management (SFM) Inventory and monitoring for forest sustainability: criteria and indicators Models of tropical forests for the conservation of biodiversity Integrating information and models across spatial and temporal scales for SFM Climate and carbon models in relation to sustainability New techniques for the statistical analysis of sustainability data Uncertainly analysis in modeling and monitoring for SFM Forest data, information and model archives

There are major contributions to be made, in particular in the areas of information and model integration where a synthesis of information and models across both spatial and temporal scales is required. There is a great need for international collaboration on the development of open and shared forest data and model repositories/archives, as well as continued development of forest information systems.

Conserving habitat calls for hands-on approach

Australian Forest Grower 31:28-29 (2008)

Mixed Species Plantations: Prospects and Challenges

Forest Ecology and Management, 233:383-390 (2006)

About 2% of English-language literature on plantations deals with mixed-species plantations, but only a tiny proportion (<0.1%) of industrial plantations are polycultures. Small landholders are more innovative, with 12% of Australia’s farm forestry plantations under mixed-species plantings, and 80% of Queensland’s farm forestry as polycultures. We examine reasons for this discrepancy, and explore the history, silviculture and economics of polycultures. Financial analyses suggest that a yield stimulus of 10%, depending on product and rotation length, may be sufficient to offset increased costs associated with planting and managing a mixed-species plantation, a stimulus that has been demonstrated in many field trials. We conclude that the main obstacle to commercial uptake of polycultures in industrial plantations may be the lack of operational-scale demonstrations coupled with reliable financial analyses.

Growth and Species Interactions of Eucalyptus pellita in a Mixed and Monoculture Plantation in the Humid Tropics of North Queensland

Forest Ecology and Management 233:285-294 (2006)

This study investigated whether mixed-species designs can increase the growth of a tropical eucalypt when compared to monocultures. Monocultures of Eucalyptus pellita (E) and Acacia peregrina (A) and mixtures in various proportions (75E:25A, 50E:50A, 25E:75A) were planted in a replacement series design on the Atherton Tablelands of north Queensland, Australia. High mortality in the establishment phase due to repeated damage by tropical cyclones altered the trial design. Effects of experimental designs on tree growth were estimated using a linear mixed effects model with restricted maximum likelihood analysis (REML). Volume growth of individual eucalypt trees were positively affected by the presence of acacia trees at age five years and this effect generally increased with time up to age 10 years. However, the stand volume and basal area increased with increasing proportions of E. pellita, due to its larger individual tree size. Conventional analysis did not offer convincing support for mixed-species designs. Preliminary individual-based modelling using a modified Hegyi competition index offered a solution and an equation that indicates acacias have positive ecological interactions (facilitation or competitive reduction), and definitely do not cause competition like a eucalypt. These results suggest that significantly increased in growth rates could be achieved with mixed-species designs. This statistical methodology could enable a better understanding of species interactions in similarly altered experiments, or undesigned mixed-species plantations.

Can the Lessons from the Community Rainforest Reforestation Program in Eastern Australia be Learned?

International Forestry Review 8:256-264 (2006)

The Community Rainforest Reforestation Program (1993-2000) was an attempt to create healthy vegetated catchments that maximize wood production, environmental protection and employment in eastern Australia. Despite a AUD10 million outlay, these goals were not fulfilled, because of limited resources and continually changing circumstances (goals, staff, institutions) that hampered the efforts of both researchers and coordinators. Both technical and managerial lessons need to be learned: blanket guidelines are rarely helpful because species, nutrition and silviculture need to be matched to each site; vigour, provenance and nutrition of nursery stock is critical to plantation success; health surveillance should not be overlooked; early growth trends may not reflect commercial outcomes; experiments should be planned and adequately funded to examine mission-critical problems thoroughly; and records should be archived, and secured in more than one location. Inability to securely maintain long-term forest research data has been a common failing in many forestry endeavours. Experience suggests that researchers should rely on their professional networks rather than their employing agency to secure data and other records contributing to a professional knowledge base.

Spatially-explicit competition indices and the analysis of mixed-species plantings with the Simile modelling environment

Forest Ecology and Management 233:295-302 (2006)

Individual-based modelling and analysis of forest experiments has been made more accessible to researchers with the advent of modelling environments like Simile from www.simulistics.com. Individual-based analyses of tree growth data offer insights not possible with plot-based analyses, especially when the original experimental design has been compromised by mortality or other unforeseen events. The paper illustrates how Simile can be used for individual-based analyses of mixed plantings, and how it can be used to explore the consequences of the resulting statistical models. A mixed-species planting of Eucalyptus pellita and Acacia peregrina is used to illustrate possibilities.

Experiment designs to evaluate inter- and intra-specific interactions in mixed plantings of forest trees

Forest Ecology and Management 233:366-374 (2006)

A review of three mixed-species trials reveals the utility of competition indices for evaluating inter- and intra-specific interactions between trees, the desirability of experiments that span a range of tree spacing and composition to inform calibration of these competition indices, the need for extremes of species composition and stand density to calibrate response surfaces, and the far-reaching impact of edge-effects. Experiment layouts commonly used for mixed-species trials in forestry (such as replacement series) rarely provide a strong basis to calibrate competition indices and response surfaces. Alternative designs involving systematic changes in species composition may offer a better basis for calibrating response surfaces, especially when used in conjunction with designs that vary tree spacing systematically. Systematic spacing designs (such as Pudden clinal plots, Marynen plaids and Nelder fans) are well established, but designs that vary composition systematically are less common. The Goelz triangle and an alternative are contrasted to illustrate how both may offer inspiration when designing trials for mixed-species research in forestry.

Modelling growth, recruitment and mortality to describe and simulate dynamics of subtropical rainforests following different levels of disturbance

Forest Biometry, Modelling and Information Sciences 1:22-46 (2006)

The capacity of rainforests to recover from logging disturbance is difficult to model due to the compounding interactions between long-term disturbance effects, natural dynamics, site characteristics and tree species regeneration strategies. The aim of this study was to develop a quantitative model using over three decades of data from stands subjected to various levels of disturbance ranging from natural, through increasing intensities of tree removal to intensive logging. Data for trees >10 cm diameter at 1.3 m above the ground (dbh) in subtropical rainforest of north-east New South Wales, Australia were used. Botanical identity of trees at species level, species-specific shade tolerance and size at maturity were used to classify 117 species into five groups. These groups include the emergent and shade tolerant main canopy species, shade tolerant mid canopy species, shade tolerant understorey species, moderate shade tolerant species, and shade intolerant tree species. Multilevel nonlinear regression was used to estimate growth, recruitment and mortality parameters, based on the assumption of variations in tree species performance at both the plot and tree levels. The species group, tree size and competition from larger trees accounted for most variation at the tree level. Significant stand level variables included topography (elevation, slope and aspect), stand basal area, and time since the disturbance. The final model is a classical matrix management-oriented model with an ecological basis and maximum size-dependent parameters of ingrowth and outgrowth. The model provides a tool to simulate stand performance after logging and to assess silvicultural prescriptions before they are applied. Simulations with estimated parameters indicate that moderate harvesting (47% overstorey basal area (BA) removal) in a checkerboard of logged and unlogged patches (group selection) on a 120-year cycle could enable sustainable timber production without compromising the ecological integrity in these rainforests. This is due to reduced logging damage in group selection, which also released retained stems and facilitated recruitment of both shade tolerant and intolerant trees. Single-tree selection (35% BA removal) created small canopy gaps that resulted in low recruitment, a slight increase in the growth of retained stems and recovery time of 150 years. Intensive single-tree selection (50% BA removal) resulted in high logging damage that increased recovery time to 180 years. Intensive logging (65-80% BA removal) decreased the stem density and created larger canopy gaps allowing for high growth rates and recruitment of both shade tolerant and intolerant trees. However, few retained stems and high mortality of recruits, increased the recovery time to 180-220 years. Pre-harvest climber cutting coupled with poisoning of nontimber species followed by logging could allow harvesting on a 300-year cycle. Shorter logging cycles may lead to changes in species composition as well as in the forest structure.

Improving productivity in mixed-species plantations

Forest Ecology and Management, 233:193-194 (2006)

Mixed species plantations are often promoted as being environmentally preferable to monocultures, but are rarely considered operationally viable by commercial forest growers. Despite many publications documenting benefits demonstrated in research studies (e.g., Kelty 2006; Forrester et al. 2006b; Wood and Vanclay 1995), and despite continuing calls from a wide range of advocates for mixed-species plantations, polyculture remains the exception rather than the rule in industrial plantation forestry (Nichols et al 2006).

A proposal for stewardship support to private native forests in NSW

Vanclay, J., D. Thompson, J. Sayer, J. McNeely, D. Kaimowitz, A. Gibbs, H. Crompton, D. Cameron, I. Bevege, 2006. A proposal for stewardship support to private native forests in NSW. The Southern Cross Group of forest researchers and practitioners. ISBN 0-9775976-0-1.

The Southern Cross Group is proposing a completely new approach to private forest management in NSW based on stewardship support. This means that incentives will be used to encourage landholders to manage their forests in a way that maintains their environmental and other values for the community, without compromising their value as a resource to the farming community. Importantly, the Southern Cross Group system will foster good outcomes through innovation rather than through cumbersome and onerous prescriptions. Private forests in NSW are important as a source of timber as well as for the conservation values they provide to the general community. Landholders should be encouraged to manage them in a way that preserves their productive capacity and their conservation values for the long term. At present, however, neither the current regulatory regime, including the Private Native Forest legislation and proposed code of practice, nor the current market regime encourages sustainable management of the State's private timber resources. The Southern Cross Group has designed an effective and simple way of fostering and rewarding good stewardship of private native forests. Good stewardship may be viewed as a 'duty of care' responsibility that should be enforced by legislation, or as an environmental service that should be recognised and rewarded. The distinction is academic: the reality is that incentives are more effective than punitive regulations. Good environmental outcomes for most forests depend on active management and, especially in the case of private native forests, on incentives for continuing management. The challenge is to devise an equitable scheme that sends the right signals for forest management, is cost-effective to administer, and represents a worthwhile investment in terms of the public good generated. We believe the way forward is with simple, transparent indicators that provide an immediate and ongoing incentive. Under our proposal, landholders will receive an annual cash payment as a reward for progress towards specific outcomes. Rather than complicated targets, we are proposing a simple, two-tiered system that will give enough incentive to landholders to provide the environmental services desired by the community. The first tier rewards and encourages landholders to regenerate more forest, to retain big trees, and to stimulate tree growth on private land. The second tier rewards and encourages stewardship of endangered species and ecological communities. These incentives will be simple to apply and audit, and will encourage landholders to learn about and encourage biodiversity on their land, and to consider it part of their income portfolio. This system will contribute to farmers seeing forests as core business, both as part of their income stream and as part of their environmental stewardship responsibilities. When all farmers view forests in this way, Australia will reap the benefit of forests that are more diverse and productive, and a forest estate that no longer continues to shrink.

Diameter growth performance varies with species functional-group and habitat characteristics in subtropical rainforests

Forest Ecology and Management 225:1-14 (2006)

We examined tree diameter growth in 20 plots subjected to various disturbance intensities (natural, low, moderate and intensive logging) in a bid to understand the general tree growth responses in relation to habitat characteristics in subtropical rainforests of north-eastern NSW, Australia. Species-specific regeneration strategy, maximum size and level of shade tolerance were used to classify species into five groups: emergent and shade tolerant main canopy (group 1), shade tolerant mid canopy (2), shade tolerant understoreys (3), moderate shade tolerant (4) and shade intolerant (5) tree species. Data series for trees
10 cm diameter at 1.3 m above the ground level (dbh) providing observations spanning over 36 years were used in multilevel regression analyses. The results showed that spatial and temporal effects in tree growth at the stand level are a combination of the differences between species functional-group compositions and environmental gradients. High growth responses were observed in the shade intolerant species while increasing level of shade tolerance and decreasing maximum size decreased trees growth rates. Tree growth increased with altitude on a large scale across regions, and with disturbance intensity on a small scale at the plot (stand) level. Increase in northness (south through flat to north facing sites) increased growth in species group 1 for trees <67 cm>dbh, but beyond this dbh threshold the opposite was true. These showed that saplings of species group 1 may require increased illumination to reach the forest canopy, but once in the canopy, low soil water availability may be limiting to tree growth in the north facing sites. Decrease in northness was associated with increased growth in species group 2 indicating that reduced illumination and improved soil moisture in the south facing sites were conducive for maximum growth in this species group. Maximum growth potential in species groups 4 and 5 increased with decrease in eastness, suggesting that the increased afternoon solar radiation and temperature were conducive for high growth rates in these species. Although topographic gradient may determine the spatial and temporal variations in tree growth where growth appeared to increase from the crest down the slope into the creek/gully, its effects on soil fertility and water availability, and interactions between these and other factors may make it difficult to discern clear growth patterns.

Regeneration changes in tree species abundance, diversity and structure in logged and unlogged subtropical rainforest over a thirty six year period

Forest Ecology and Management 236:162-176 (2006)

The long-term effects of logging treatments on rainforest regeneration are difficult to quantify due to compounding interactions with natural dynamics, site characteristics and tree species. The aim of this study was to examine regeneration differences over a 36-year period in stands subjected to various levels of disturbance ranging from natural, through an increasing intensity of individual tree removal to intensive logging. Multivariate and univariate analyses of trees ¡Ý 10 cm diameter at 1.3 m above the ground (dbh) showed that regeneration responses were generally correlated with disturbance gradient. In the undisturbed controls there were gradual changes that had no significant effects on tree species richness and diversity, stem density, or diameter distribution. Gradual changes were also observed during the early stages of regeneration following logging. However, in logged sites changes in tree species richness and diversity, stem density and diameter distribution became more rapid with time, and significant changes were observed. Similar regeneration events across site and disturbance levels resulted in three identifiable stages. In the first stage, lasting about 10 years, stem density of abundant shade tolerant trees decreased with no discernable changes in tree species richness. In the second stage, also lasting about 10 years, tree species richness and diversity, as well as stem density decreased to minima due to localised species turnover and net mortality. In the third stage, recruitment surpassed mortality and reversed the net loss of both species and stems, as tree species assemblages began to return to pre-disturbance levels. Sites subjected to individual tree selective logging returned to their pre-logging states in all aspects within 35 years of logging, but diameter distribution of trees ¡Ý 40 cm dbh showed low density compared to that observed in the controls. After 15¨C30 years, sites subjected to more intensive logging returned to their pre-logging levels of stem densities, species abundance and richness, but after 35¨C44 years of regeneration this sites had low species diversity and high densities of both the small sized stems and shade intolerant tree species. More intensively logged sites also had a low density of shade tolerant tree species compared to the controls. This suggests that the restoration of forest structure takes considerably longer than the restoration of tree species richness and abundance following logging in these forests. A high rate of stand basal area growth and a modest diameter distribution of lager trees ¡Ý 40 cm dbh were observed in moderate tree selection logging. This indicates high timber production potential at moderate tree selection rate in this type of forest. However, if the stem size distribution of larger trees is to be maintained, a logging cycle longer than 50 years is necessary.

Mixed-Species Plantations of Eucalyptus with Nitrogen Fixing Trees: A Review.

Forest Ecology and Management, 233:211-230 (2006)

Mixed-species plantations of Eucalyptus with a nitrogen (N2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shade-tolerant species. Successful mixtures also have significantly higher rates of N and P cycling than Eucalyptus monocultures. It is therefore important to select N2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2-fixation. While the dynamics of N2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly (P<0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series.

Beer bottle tops: a simple forest management game

International Forestry Review 8:432-438 (2006)

Forest planning and management concepts can sometimes be difficult to grasp. Games provide an effective way to demonstrate different concepts and facilitate deeper understanding of approaches and practices to sustainable forest management. In this paper we describe a game devised to demonstrate alternative ways to set allowable harvest levels in large (>10,000 ha) native forest planning units. The game requires minimal materials (photocopies of relevant maps and a few hundred beer bottle tops), and can be played and debriefed in 2-3 hours. The game focuses on the principles underlying area control and volume control of timber harvesting, and provides a basis for discussion of inventory and monitoring needs. The game has been popular and effective in courses for forestry professionals in developing countries, and for students in an undergraduate forestry course.

Illumination-size relationships of 109 coexisting tropical forest trees

Journal of Ecology 94:494-507 (2006)

1 Competition for light is a central issue in ecological questions concerning forest tree differentiation and diversity. Here, using 213 106 individual stem records derived from a national survey in Ghana, West Africa, we examine the relationship between relative crown exposure, ontogeny and phylogeny for 109 canopy species.

2 We use a generalized linear model (GLM) framework to allow interspecific comparisons of crown exposure that control for stem-size. For each species, a multinomial response model is used to describe the probabilities of the relative canopy illumination classes as a function of stem diameter.

3 In general, and for all larger stems, canopy-exposure increases with diameter. Five species have size-related exposure patterns that reveal local minima above 5 cm d.b.h., but only one, Panda oleosa, shows a local maximum at a low diameter.

4 The pattern of species exposures at 10 cm diameter is consistent with two overlapping groups, of which the smaller (21 species, including most pioneers) is generally better exposed.

5 Relative illumination rankings amongst species are significantly maintained over a wide range of stem sizes. Species that are well exposed at small diameters are therefore also more likely to be well exposed at larger diameters, although two species in the most exposed 25% of species at 10 cm d.b.h. drop to the lowest illumination quartile at 40 cm d.b.h., and three demonstrate the opposite (low-to-high) pattern.

6 Species capable of achieving the largest diameters are generally recorded less frequently in shade than are smaller species, even when compared as saplings, suggesting that species achieving large mature sizes are generally shade intolerant when small. Controlling for phylogeny reveals that this relationship holds across independent lineages.

7 We also find evidence that the range of strategies encountered is influenced by disturbance regimes.

8 We interpret our results as indicating a continuum of strategies that reflect an evolutionary trade-off between a species’ mature size and its general shade-tolerance, in combination with differentiation based on disturbance based opportunities. Species that appear similar can therefore remain ecologically distinct over their lifetimes.

Deforestation: correlations, possible causes and some implications

International Forestry Review 7:278-293 (2005)

Changes in national forest areas during 1990-2000 are contrasted with other variables to illustrate correlations and provoke discussion about possible causes. Twenty-five statistically-significant correlations (including rural population, life expectancy, GDP, literacy, commerce, agriculture, poverty and inflation) are illustrated and a statistical model suggests that good governance, alternative employment opportunities, and payments for environmental services may be effective in combating deforestation. The data suggest that a global forest convention may need to be supported by substantial and carefully-targeted development assistance to foster good governance.

Dynamics of tree diversity in undisturbed and logged subtropical rainforest in Australia

Biodiversity and Conservation 14:2447-2463 (2005)

In subtropical rainforest in eastern Australia, changes in the diversity of trees were compared under natural conditions and eight silvicultural regimes over 35 years. In the treated plots basal area remaining after logging ranged from 12 to 58 m2 per ha. In three control plots richness differed little over this period. In the eight treated plots richness per plot generally declined after intervention and then gradually increased to greater than original diversity. After logging there was a reduction in richness per plot and an increase in species richness per stem in all but the lightest selective treatments. The change in species diversity was related to the intensity of the logging, however the time taken for species richness to return to pre-logging levels was similar in all silvicultural treatments and was not effected by the intensity of treatment. These results suggest that light selective logging in these forests mainly affects dominant species. The return to high diversity after only a short time under all silvicultural regimes suggests that sustainability and the manipulation of species composition for desired management outcomes is possible.

Using a Typology of Tree-Growers to Guide Forestry Extension

Annals of Tropical Research 27:97-103 (2005)

This paper introduces the concept of a landholder typology as a means for targeting non-industrial forest policy and extension. An intuitive typology for farm forestry in sub-tropical Australia is developed, and used to illustrate how an extension strategy can be varied to reach the various groups in a cost-effective manner. Types of tree growers identified include lifestylers, those deriving supplementary income from forestry, and those who aim to generate their primary income from forestry. It is argued that the nature of extension effort should be targeted towards the information needs within each grower type.

What would a Global Forest Convention mean for tropical forests and for timber consumers?

Journal of Forestry 103:120-125 (2005)

A global forest convention has been advocated for about 15 years, but progress is slow and positions of advocates and opponents appear entrenched. We review several case studies and offer new empirical evidence relating to causes of and remedies for deforestation. We find no evidence to suggest that a forest convention will be effective in halting deforestation. Our data indicate that development assistance may be most effective approach to save forests in developing countries. It appears that "money speaks louder than words". We conclude that a global forest convention will be ineffective unless accompanied by substantial and well-directed development assistance.

Growth stress in Eucalyptus dunnii

Australian Forestry 68:144-149 (2005)

Growth stress in 9-year-old plantation-grown Eucalyptus dunnii was assessed by measuring longitudinal growth strain. Strain varied considerably (370 to 1560 um-1) and was sufficiently heritable (h2=0.3-0.5) that tree breeding may be an effective way to reduce the indicence of growth stress in this species. Although the formation of longitudinal growth strain appears to be under strong genetic control (P=0.0015), there was a tendency for tall thin trees to exhibit higher stress than short thick trees (P=0.025 for height/diameter ratio). Two provenances and three families identified in this study show potential as superior material for further tree breeding.

Spiral and interlocking grain in Eucalyptus dunnii

Holz als Roh- und Werkstoff 63:372-379 (2005)

Spiral grain in 181 trees from a 9-year-old plantationgrown Eucalyptus dunnii was normally distributed with mean −0.33 degrees (to the left) and standard deviation 1.7 degrees, and was affected by family and by crown asymmetry. Interlocking grain was common, exhibiting a mean amplitude of 3.4 degrees (standard deviation 1.5◦) and a mean wavelength of 39 mm (standard deviation 12 mm). The relatively large amplitude of interlocking grain means that most trees will have spiral grain that alternates between left and right during each year. The wavelength of interlocking grain is influenced by tree size, but amplitude of interlocking is under genetic control. Both spiral grain and the amplitude of any interlocking were heritable (h2 = 0.99 and 0.63 respectively).

Indicator groups and faunal richness

Forest Biometry, Modelling and Information Sciences 1:105-113 (2004)

Species richness is a popular indicator of ecosystem vitality, but is difficult to assess. Many natural resource managers seek an efficient bioindicator, but the link between candidate indicators and the richness of other taxononic groups remains elusive. A series of faunal surveys in the Mbalmayo Forest Reserve in Cameroon suggest that it may be possible to devise faunal bioindicators. The species richness of birds, of butterflies and of termites is significantly correlated with total faunal richness across eight species groups, suggesting that these groups may have potential as bioindicators, alone or in combination. Although expensive, further research is warranted because of the substantial potential benefits and implications of the use of indicator groups.
Keywords: alpha diversity, species richness, bioindicator, surrogate, butterflies, termites.

Modeling deforestation at distinct geographic scales and time periods in Santa Cruz, Bolivia

International Regional Science Review 27:271-296 (2004)

This article analyzes geo-referenced data to elucidate the relations between deforestation and access to roads and markets, attributes of the physical environment, land tenure, and zoning policies in Santa Cruz, Bolivia. It presents separate models for Santa Cruz as a whole and for seven different zones within Santa Cruz, as well as for two different time periods (pre-1989 and 1989 to 1994). The relation between deforestation and the explanatory variables varies depending on geographic scale and the zone and time period analyzed. At the department scale, locations closer to roads and the city and places that have more fertile soils and wetter climates have a greater probability of being deforested. The same applies to colonization areas. Protected areas and forest concessions are less likely to be deforested. Nevertheless, in many specific zones, these variables had no significant impact or actually had the opposite impact than in the entire department. Most of these relations were weaker between 1989 and 1994 than in the previous period.

The One-minute Modeller: An Introduction to Simile

Annals of Tropical Research 25:31-44 (2003)

The Simile programming language provides a powerful and relatively easy to use medium for developing models and simulating the behaviour of forestry systems. This is a highly visual approach to modelling, in that the flow diagram is in effect the computer program. This paper provides a simple introduction to use of the Simile programming language for potential users, which has been developed to provide an initial understanding of the programming features and steps in classes and for workshops.

Modelling interactions amongst people and forest resources at the landscape scale

Small-scale Forestry 2:117-120 (2003)

FLORES, the Forest Land Oriented Resource Envisioning System, is a framework to facilitate quantitative modelling of ecological, economic and social issues at the landscape scale. This issue of Small-scale Forest Economics, Management and Policy describes the evolution of FLORES from a concept to a series of models calibrated for diverse locations, and documents the lessons learned.

Why model landscapes at the level of households and fields?

Small-scale Forestry  2:121-134 (2003)

Sustainable resource management relies upon many disciplines and deals with complex interactions at the landscape scale. Many of the issues at the landscape scale arise from decisions taken at the household level and affect land use in fields and in small patches of forest. Spatially-explicit modelling of these units is desirable because it enables rigorous testing of model predictions, and thus of underlying propositions. The greatest insights may be obtained by participatory modelling of these processes as we understand them. Despite this, few models simulate dynamics at the household and field level. FLORES, the Forest Land Oriented Resource Envisioning System, is a simulation system that attempts to bring these elements together into a coherent package to assist stakeholders to explore options and their implications. The hallmark of FLORES is explicit modelling of the interrelationship between actors and land parcels within a spatial framework. FLORES demonstrates the feasibility and possible benefits of modelling at this scale.

Realizing opportunities in forest growth modelling

Canadian Journal of Forest Research 33: 536-541 (2003)

The world is continually changing: the emergence of new technology and new demands for pertinent information pose new challenges and possibilities for forest management. Are forest growth models keeping up with client needs? To remain relevant, modelers need to anticipate client needs, gauge the data needed to satisfy these demands, develop the tools to collect and analyze these data efficiently, and resolve how best to deliver the resulting models and other findings. Researchers and managers should jointly identify and articulate anticipated needs for the future, and initiate action to satisfy them. New technology that offers potential for innovation in forest growth modelling include modelling software, automated data collection, and animation of model outputs. New sensors in the sky and on forest machines can routinely provide data previously considered unattainable (e.g., tree coordinates, crown dimensions), as census rather than sample data. What does this revolution in data availability imply for forest growth models, especially for our choice of driving variables?

Growth modelling and yield prediction for sustainable forest management

The Malaysian Forester 66:58-69 (2003)

A brief synthesis of milestones in forest growth modelling helps to establish research topics for further model development in managed tropical forests. Forest growth models have become indispensable for forest management, but need further development to realize their full utility. Feedback from monitoring predictions versus realizations should provide the basis for continuing improvement, both in growth modelling and in forest management.

Sustainable Forestry in the Tropics: panacea or folly?

Forest Ecology and Management 172:229-247 (2003)

The profitability of uncontrolled logging can be a significant obstacle to sustainable forest management, especially in the tropics. Rice et al. (1997) have argued that not only does traditional selective logging provide higher returns but also incurs less damage to forests than sustainable forest management systems that involve harvesting of many species and the creation of large gaps in the forest canopy to foster regeneration of light-demanding species. They claimed that protected areas were the only viable way to conserve forest ecosystems and proposed that loggers be allowed to log forests selectively once, after which the forests should become parks. Here we respond to the challenge posed by Rice et al. by exhaustively reviewing the evidence regarding the viability and desirability of sustainable forest management in the tropics. Following Rice et al., we use the term conventional timber harvesting to refer to existing practice, which typically pays little attention to maintaining long-term timber supply. Sustainable timber management implies taking steps to ensure forests continue to produce timber in the longer term, while maintaining the full complement of environmental services and non-timber products of the forest.

Empirical studies tend to confirm the conclusion of Rice et al. (1997) that although sustainable timber management sometimes provides reasonable rates of return, conventional timber harvesting is generally more profitable. This implies that without additional incentives, one cannot expect companies to adopt sustainable management. The shortsightedness of many loggers, the slow rise in international timber prices, political uncertainty, and tenure insecurity simply reinforce this tendency. However, we reject the claim that sustainable timber management generally damages forests more than conventional logging. Rice et al. base their conclusion largely on the particular case of mahogany extraction in Bolivia, and even there it may not hold. In many cases, sustainable timber management performs better in terms of carbon storage and biodiversity conservation than conventional logging approaches, as well as producing more timber. If new carbon markets emerge, sustainable forest management might compete effectively with conventional timber harvesting. Timber certification systems may also provide a sufficient incentive for sustainable forest management in certain circumstances.

Participation and model-building: Lessons learned from the Bukittinggi workshop

Small-scale Forestry 2:135-154 (2003)

FLORES (the Forest Land Oriented Resource Envisioning System) was initially constructed by 50 people during a multidisciplinary workshop in Bukittinggi, Sumatra, in 1999. It proved that a model of a complex system could be constructed in a participatory way by a diverse team; that it could be done with a graphically-based package such as Simile; and that the resulting model could remain reasonably accessible to all participants, and could run on an ordinary notebook computer. Many useful insights can be gained through building such a model, and subsequent experience has demonstrated that modelling in this way can foster continuing interdisciplinary collaboration. Participants founded the FLORES Society, a loose collective open to all researchers interested in pursuing the development and use of such models.

A model to help people to realize sustainable forestry futures

Annals of Tropical Research 25:53-64 (2003)

People usually know how they want their situation to change to secure a better future – but they do not always know how to change their situation. Initiatives intended to secure a better future do not always work as intended, and may have unintended side effects. Computer models can help advocates explore consequences of proposed initiatives, so they can make informed selections of alternatives, secure in the knowledge that consequences have been thoroughly investigated. By encouraging people to explore scenarios, models empower people to be more innovative and less dependent on technocrats. Models also enable planners to experiment with policy without risks to people or to the environment. Emerging software solves many technical limitations, but the real issue is not software, but rather the provision of a supportive framework within which people can express and experiment with ideas. FLORES, the Forest Land Oriented Resource Envisioning System, provides such a framework to stimulate interdisciplinary collaboration between researchers, practitioners and clients. Two recent workshops have demonstrated the feasibility of FLORES, one of which provides the subject matter for a forthcoming issue of Small-scale Forest Economics, Management and Policy. However, FLORES is not about software; it is about providing the means to explore the consequences of alternative scenarios. Ultimately, FLORES is not a physical package, but an association of users and the interactions they have amongst themselves, and with the people involved in policy-making. By promoting this emerging network and providing technical support we encourage more people, especially those from developing countries, to influence the development of FLORES and the issues that can be explored within it.

ZimFlores: A model to advise co-management of the Mafungautsi Forest in Zimbabwe

Small-scale Forestry 2:185-210 (2003)

ZimFlores (version 4) is the outcome of a participatory modelling process and seeks to provide a shared factual basis for exploring land-use options for the communal lands surrounding the Mafungautsi forest. The ZimFlores experience underscores the importance of a sharing a common problem and a common location in which all participants have an interest. Participatory modelling has proved an effective way to consolidate a diverse body of knowledge and make it accessible. Results demonstrate the importance of model outputs that are diagnostic, and which offer insights into the issues under consideration.

Multi-agent simulation of alternative scenarios of collaborative forest management

Small-scale Forestry 2:277-292 (2003)

International calls for sustainable development advocate that forest management should be carried out in a multi-stakeholder environment. The importance of community participation is acknowledged in the Indonesian Act No. 41 on Forestry (1999). However, it is not clear how to achieve this in areas already allocated to a concession holder. Current regulations offer little flexibility for concessionaires to develop site-specific management, or to involve local communities in forest management. The research reported here examines the application of simulation techniques to explore scenarios of sustainable forest management addressing those limitations. Several scenarios have been developed using multi-agent simulation to examine social and biophysical issues. Of the four scenarios examined in this study, collaborative forest management involving both the concessionaire and the local community appears to offer the most promising pathway toward sustainability.

Participatory modelling to enhance social learning, collective action and mobilization among users of the Mafungautsi Forest, Zimbabwe

Small-scale Forestry 2:313-326 (2003)

Participatory modelling can be a useful process to encourage critical examination of livelihood options and foster sustainable natural resource use through enhanced social learning, collective action and mobilization. The broom-grass group in the Mafungautsi Forest Reserve serves as a case study of the process and outcomes of such participatory modelling. Innovative group facilitation methods enhanced participation in the modelling process. The modelling process complements broader efforts to achieve higher levels of adaptive collaborative management.

Is sustainable forestry economically possible?

In: D. Pearce, C. Pearce and C. Palmer (eds), Valuing the Environment in Developing Countries: Case Studies. Edward Elgar, Cheltenham, p. 447-500 (2002).

Concern about the rate at which the world's forests are being depleted is wide-spread. Recent international calls for radical efforts to reduce deforestation include the United Nations Inter-governmental Forum on Forests of the UN Commission on Sustainable Development, and the World Commission on Forests and Sustainable Development. This concern reflects an appreciation of the ecological and economic functions of forests: as providers of timber and many non-timber predicts, as the habitat for much of the world's biological diversity, and as regulators of local, regional and global environments. These functions are at risk. Most of the forest clearance is in areas of high forest cover and high human population pressure in tropical areas for agriculture. In temperate and boreal areas the pressures from logging are more important. But in all areas, forestry itself has an important role to play both as a partial cause of deforestation, and, if practiced wisely, as a potential source of salvation for at least some of the world's forests. In terms of its causal role, forestry tends to open up primary forest areas, enabling colonists to move in, using roads forged by the timber companies. In some parts of the world, forests are converted not to agriculture but to biomass plantations of fast growing trees or to other agro-industries based on tree-crop plantations such as palm oil and rubber. Here the primary agent is not the peasant, but the richer elements of local and international society. How, then, can the world's forests be used more wisely? It is this admittedly grand and complex question that we seek to answer in this chapter.

The Effectiveness of Parks

Science 293:1007 (2001)

Bruner et al. (1) examined the effectiveness of parks in the tropics, drawing on survey data to support three conclusions: (i) parks have been effective; (ii) parks need more support; and (iii) parks should remain a central component of conservation strategies. These conclusions remain equivocal.

Structure and floristic composition of flood plain forests in the Peruvian Amazon: II. The understorey of restinga forests.

Forest Ecology and Management 150:59-77 (2001)

Structure and floristic composition of small trees and shrubs (1.5 m height to 10 cm diameter at breast height was described in two flood plain forests of the lower Ucayali river, Peruvian Amazon. The forests were of the high and low restinga type, on an annual average flooded around 1 and 2 months, respectively. The soils were nutrient rich entisols, and the vegetation forms closed high canopy forests with presence of emergents. A total of 25 permanent sample plots covering 0.64 ha were established. They were nested within six quadratic 1 ha permanent sample plots where large individuals (>10 cm DBH) were inventoried. Overall average density and basal area of the understorey were 4458 ha and 5.0 m2 /ha, respectively. The families of Moraceae, Leguminosae, Annonaceae, Euphorbiaceae, and Lauraceae were among the most important tree families, while important shrub and small tree families were Violaceae, Rubiaceae, Melastomataceae, and Olacaceae. Two hundred eight and 204 tree species were registered in the restinga forest overstories and understories, respectively. Fifty-six percent of the species were shared between the two forest strata, while around 22% were confined to each of them. Species present only in the understorey were predominantly shrubs or treelets, while some of the species with a presence only in the overstorey were probably early succession species about to disappear from the forests.

The Amazon flood plain forest tree Maquira coriacea (Karsten) C.C. Berg: Aspects of ecology and management

Forest Ecology and Management 150:103-113 (2001)

Maquira coriacea is a commercial tree species growing throughout the Amazon flood plain forests. Densities up to 14/ha of individuals, >10 cm diameter at breast height (DBH) were observed, corresponding to a basal area of 2 m2/ha and a volume of 38 m3/ha. The primary period of fruiting coincided with the annual flooding, but fruits were also produced in other parts of the year. Seedlings with densities up to 150/m2 were concentrated around mother trees, and the stocks fluctuated much over the year due to mortality caused by flooding and wilting in dry periods. Growth data mainly from nine 1 ha permanent sample plots were used to develop models of the height-diameter relationship and diameter increment. These relationships indicated that the optimal felling limit for maximum volume production was 120-130 cm DBH, which can be obtained in 150-260 years. Since seed production has been observed in much smaller individuals, such diameter limits should not be detrimental to regeneration.

Structure and floristic composition of flood plain forests in the Peruvian Amazon: I. Overstorey

Forest Ecology and Management 150:27-57 (2001)

Three Peruvian flood plain forests adjacent to the Ucayali river were sampled using nine 1 ha permanent sample plots in which stems exceeding 10 cm DBH were identified and measured. These plots were measured four times during 1993-1997. Three plots were established in each of the three forest types high restinga, low restinga, and tahuampa, characterised in part by an annual inundation of one, two and four months per year, respectively. Stem density varied from 446 to 601 per hectare, and the basal area ranged between 20 and 29 m2/ha. A total of 321 species were recorded in the nine hectare sample, with 88-141 species in each 1 ha plot. Species composition indicated a relatively low similarity between the forest types. Plots with the longest flooding contained the most species, expressed both as per unit area as well as per 1000 stems. The flood plain forests contained fewer tree species than adjacent non-flooded terra firme forest. Family importance values were calculated for each forest. In all three forests Leguminosae, Euphorbiaceae, Annonaceae and Lauraceae were important. The Moraceae family was conspicuous in both high restinga and low restinga. The Arecaceae and Meliaceae were notable in high restinga, as was Rubiaceae in low restinga. Lecythidaceae, Sapotaceae and Chrysobalanaceae exhibited relatively high values in the tahuampa forest. High species importance values were obtained for Maquira coriacea, Guarea macrophylla, Terminalia oblonga, Spondias mombin, Ceiba pentandra, Hura crepitans, Eschweilera spp., Canipsiandra angustifolia, Pouteria spp., Licania micrantha, Parinari excelsa and Calycophyllum spruceanum. Among the species of smaller stature, Drypetes amazonica, Leonia glycicarpa, Theobroma cacao and Protium nodulosum attained high values.

Forest dynamics in flood plain forests in the Peruvian Amazon: Effects of disturbance and implications for management

Forest Ecology and Management 150:79-92 (2001)

Forest dynamics were studied from 1993 to 1997 for individuals > 10 cm DBH in nine 1 ha permanent sample plots. They were established in natural flood plain forests located on the lower Ucayali river in the Peruvian Amazon. After inventories of three plots in each of three forest types, a light and a heavy felling treatment were applied to each of the two plots, while a third plot was kept untreated. Average annual stem mortality and recruitment rates in the untreated plots were among the highest observed in neotropical rain forests: mortality 2.2-3.2% per year, recruitment 3.0-4.6% per year. Dead individuals deviated significantly from random dispersion towards clumping. The average annual basal area growth was around 1 m2/ha per year, corresponding to average annual basal area growth rates of 3.5-3.8% per year in the untreated plots. No decrease in basal area growth was observed even in the treated plots where annual basal area mortality rates up to 41 % during the first year were observed. The average diameter growth increased from 4.0-4.5 mm per year in the untreated plots to 5.3-6.8 mm per year in the treated plots. The stocking of commercial timber species was high with basal areas of 2.6-10.0 m2/ha and volumes of 59-240 m3/ha. The corresponding growth of basal area and volume of commercial timber species were also considerable, reaching values of 0.1-0.3 m2/ha per year and 2-9 m3/ha per year, respectively. These attributes suggested that forest management for timber production in these forests can be flexible and provide relatively high yields on a sustained basis. It appeared that management interventions can be carried out within the range of naturally occurring perturbations, although it should be noticed that only limited proportions of each habitat are disturbed at a time by nature. The patchy occurrence of habitats may provide logistic problems to management.

Codes of forest practice and related research needs.

In: A.G. Brown (ed.) Sustainable Forest Management. Proceedings of the Hermon Slade International Workshop held at Melbourne, 30 November – 4 December 1998. Crawford Fund, ISBN 0 643 06316 1, p.21-28.

This paper has aimed to set Codes of Forest Practice in the framework of the evolving debate on sustainable forest management. We suggest that most Codes of Forest Practice have been developed primarily from a biological and physical perspective. It would be useful to consider future needs for research for Codes of Forest Practice in the broader context of ecosystem management in which there is a more holistic approach and a greater concern for the aspirations and welfare of stakeholders. It will be essential to recognise people with their needs and values as part of the forest ecosystem we are researching.

Healthy forests, sound economics, social justice

Forum for Applied Research and Public Policy 13:78-84 (1998)

Concern over the management of the world's forests is becoming a hot topic, and no area is under heavier scrutiny than the tropical forests. The current rate of deforestation, especially in light of the enormous number of species these forests contain, is the primary cause for this concern. Despite this ominous trend, much can be done to protect and sustain these incredibly valuable resources.

FLORES: for exploring land use options in forested landscapes

Agroforestry Forum 9:47-52 (1998)

Incentives intended to stimulate better land use practices often don't work as intended, and can have undesirable side effects that were not foreseen. How can we better equip policy makers and their advisors to envisage fully the efficacy and consequences of initiatives? One way is to provide a decision support system. The formulation and construction of such a system offers other benefits: it would make existing information more accessible, facilitate hypotheses testing, and foster collaboration between researchers working on these issues. FLORES is such a system being developed through a partnership co-ordinated by the Center for International Forestry Research.

Estimating Sustainable Timber Production from Tropical Forests

CIFOR Working Paper No 11 (1996)

Natural forests in the humid tropics differ from temperate and plantation forests in several ways: there may be many tree species; many of these may occur infrequently; there may be a large range of tree sizes and shapes present; tree ages may be unknown and indeterminate; and despite the luxuriant appearance some rainforests, growth rates may be relatively low. This has many implications for timber harvesting and yield estimation and means that most of the estimation techniques devised for even-aged single-species forests cannot be used. A timber harvest represents the culmination of many years of growth, even in "fast growing" plantations. Thus, unlike the farmer of annual crops, the forest manager must consider the distribution of the harvest over time. Several "rules-of-thumb" for estimating the annual allowable cut are examined, with special emphasis given to the selection of the cutting cycle, to growth and harvesting models, and to inventory and monitoring systems. Strengths and weaknesses of cutting cycle analysis are discussed, and are contrasted with the more sophisticated yield scheduling systems. Tools, techniques and information sources for estimating timber yields are reviewed. Yield calculations should make full use of existing information, including data from old surveys and casual inspections. Remote sensing and geographic information systems offer several interesting possibilities for yield estimation, particularly for sensitivity testing, but are not without limitations. A check list and extensive references are given.

Estimating use-values and relative importance of Amazonian flood plain trees and forests to local inhabitants

Commonwealth Forestry Review 74:293-300 (1995)

Use-values have been advocated as a tool to compare the value of not just individual species, but also of plant families and forest types to local people, in order, for example, to identify species or habitats in need of special management or conservation. We estimated use-values in three forest types (upper restinga, lower restinga, tahuampa) on the Amazon flood plain south of Iquitos (Peru), compared two methodologies, identified the most valuable species and contrasted these valuations with the actual use of forest resources in local villages. A new method for estimating use-values was contrasted with the method of Phillips and Gentry (1993a). Despite philosophical and procedural differences, estimates were highly correlated (R2=0.86). We discuss limitations of both methods and suggest some possible enhancements. The need to discriminate between past, present and potential uses is emphasised.

Operator bias with optical wedges in point sampling

Commonwealth Forestry Review 74:158 (1995)

Point sampling, or sampling with probability proportional to size (PPS), is an efficient technique often used in timber cruising, but care must be taken to avoid operator bias.

Inventory and yield prediction for natural forest management

Australasian Forestry and the Global Environment, Proceedings of Institute of Foresters of Australia 15th Biennial Conference, Alexandra Headland, Queensland, 19-24 Sept. 1993.

Information is essential to effective forest management and planning, and its value may be gauged by the potential costs of sub-optimal decisions. Efficient yield prediction demands an integrated approach, embracing many components. All aspects of data collection, storage and analysis must be accorded equal importance. This caveat applies to area estimates, resource estimates and to growth and yield models. Inventory data provide the core of the system, and the success of the system may depend on the cost and ease of data collection. The user interface is also critical, and the flexibility to customize reports to users' requirements is essential.

Writing a scientific paper for publication

Annals of Forestry 1:199-202 (1993)

Help your readers, referees, editor and yourself by careful attention to detail. The summary should be an informative precis of facts and conclusions, not merely a description of the paper. Make the paper easy to read, don't use jargon and have a colleague check it before you submit it to a journal. Use figures rather than tables, and keep the whole paper, including tables and figures, clear, simple and to the point. Consult the journal's 'Instructions to contributors' before submitting.

Species richness and productive forest management

In: F.R. Miller and K.L. Adam (eds) Wise Management of Tropical Forests, Oxford Forestry Institute, University of Oxford, p. 1-9. (1992)

There are many reasons to preserve the biological diversity of the earth, and perhaps the most compelling is the insurance that it provides for the uncertain times ahead. The responsibility for maintaining this biodiversity falls particularly heavily on the custodians of the tropical forests, where species richness is highest. How can these forests provide for the immediate needs of local inhabitants, whilst maintaining their rich diversity for all in the longer term? A "hands-off" approach is neither practical nor necessary, and a few simple guidelines provide reasonable protection for most species. Strict nature reserves provide a small but important part of the solution. They should be large, contiguous and compact, and should be set within a matrix of production forest. Remaining fragments of old-growth forest may be critical for some specialist species and should be protected. However, reserve networks should not be restricted to old-growth forest, but should represent all vegetation types. In many cases, degraded lands may be the only option for representing some types, and they should be protected and rehabilitated. Nature reserves are only part of the solution, and must be supplemented by production forests, managed in a sympathetic way. Timber may be harvested in many ways, but for most tropical forests, polycyclic selection logging may provide the best compromise between production and maintenance of diversity. Selection logging should strive for minimal canopy opening and minimal soil disturbance. Some veteran trees should be retained to provide hollows and nesting sites for fauna. Buffer strips should be maintained along streams, and should be supplemented to form interconnecting corridors between undisturbed forest. Roads should be narrow, well engineered and well drained to minimize erosion and silting. Agroforestry can also help maintain biodiversity. Windbreaks and hedgerows should be wide, linking forested areas to create wildlife corridors, and should include a large range of plant species. Maintenance of biodiversity requires participation and good husbandry from all land custodians, not just forestry. Agriculture and urban developments are often the dominant land use, so can contribute much toward the maintenance of wildlife habitat.

Enhancing a permanent sample plot system in natural forests

The Statistician 41:525-538 (1992)

Permanent sample plots (PSPs) provide the basis for growth models and thus determine the quality of inferences made from decision support systems for forest management. Existing plots may have been adequate in the past, but changing needs and possibilities may have made data suboptimal for present demands. Funds for the establishment of additional plots are generally limited, so supplementary sampling should be based on an optimal sampling strategy employing prior information. This case study in south-east Queensland used topoclimatic strata and existing inventory data to identify where additional PSPs should be established, so as to increase the geographical and silvicultural range of the growth data collected. Some existing PSPs in areas considered over-sampled may be abandoned.

Integrated Resource Monitoring and Assessment: An Australian Perspective of Current Trends and Future Needs

Global Natural Resource Monitoring and Assessments: Preparing for the 21st century, Proceedings of the international conference and workshop, Sept 24-30, 1989, Venice, Italy.

Trends influencing inventory practice include increasing labour costs, new technology and competing demands for land use. These trends challenge land managers to devise efficient mold-purpose inventories which yield durable data to assist land management rather than just timber management. For maximum utility, inventory design should allow integration of data collected in different places, at different times, by different agencies, or for different reasons. Three things are essential for reliable integration of data: standardization, accuracy and locational information (geocodes). Clear objectives and sufficient resources (funds and staff) are also a prerequisite. Managers should try to anticipate future information requirements, and plan to meet them. Multi-resource inventories cannot be set up overnight. It is natural that ideas and procedures evolve and mature. One should start with the possible, but plan for the future.

Site productivity assessment in rainforests: an objective approach using indicator species

Proceedings of the Seminar on Growth and Yield in Tropical Mixed/Moist Forests, 20-24 June 1988, Kuala Lumpur. Forest Research Institute Malaysia, p. 225-241.

Site productivity assessment is a prerequisite for growth prediction and yield forecasting. Site index (top height at an index age) is not suitable in rain forests where tree height is difficult to measure and tree age is impossible to determine. This paper reports a study which ranked 80 permanent plots according to potential diameter increment, and established equations which allow site productivity to be determined from the presence or absence of several tree species or from geological maps and Landsat TM data. Eighteen pandemic species were selected as a basis for comparing the growth potential of each plot. Regression analysis of their individual diameter increments was used to establish the plot's growth potential. This approach ensures freedom from biases introduced by species composition and stocking. The values determined by regression were scaled for convenience, into the range 3-10. Stepwise linear regression was then used to derive equations which would enable objective assessment of the productive potential of these and other rain forest sites within the region. Validation using independent data indicated that three equations, employing species occurrence, geology and Landsat TM data, provided reliable estimates of the productive potential of rain forest.