Michelle A. Pinard

Soil disturbance and post-logging forest recovery on bulldozer paths in Sabah, Malaysia.

We examined the extent of soil disturbance associated with bulldozer yarding and the regrowth of woody vegetation on bulldozer paths (skid trails) in selectively logged dipterocarp forest. In an area logged in 1993, using conventional, i.e., uncontrolled, harvesting methods, about 17% of the area was covered by roads and skid trails. In contrast, in a 450-ha experimental area where reduced-impact logging guidelines were implemented, 6% of the area was similarly disturbed. Skid trails in the reduced-impact logging areas were less severely disturbed than those in conventional logging areas; the proportion of skid trails with subsoil disturbance was less than half that in conventional logging areas. Four years after logging, woody plant recovery on skid trails was greater in areas logged by reduced-impact than by conventional methods. Skid trails where topsoil had been bladed off had less woody vegetation than skid trails with intact topsoil. In a chronosequence of logging areas (3, 6, and 18 years after logging), species richness and stem densities of woody plants (>1 m tall, <5 cm dbh) were lower on skid trail tracks than on skid trail edges or in adjacent forest. Both richness and density increased with time since logging, but even 18 years after logging, abandoned skid trails were impoverished in small woody stems compared with adjacent forest. Minimizing soil and stand disturbance during logging appears to allow a more rapid recovery of vegetation on bulldozed soils, but the long-term fate of trees growing on compacted soils remains uncertain.

Biotic interactions in the tropics: their role in the maintenance of species diversity.

To understand how tropical ecosystems function we need to appreciate not only what plants, animals and microbes they contain, but how they interact with each other. This volume synthesizes the current state of knowledge of tropical biotic interaction, with chapters providing reviews or case studies drawn from research conducted in both Old and New World tropics, including interactions among taxa at all levels. An underlying theme of the volume is revealing the importance of the maintenance of high diversity in tropical regions.

Impacts of stem harvesting on populations of Iriartea deltoidea (Palmae) in an extractive reserve in Acre, Brazil

Population projection matrices were used to explore the population stability of Iriartea deltoidea in an extractive reserve in Acre, Brazil. Palm population structure at 5 sites was described using height class distributions; projections were based on survival probability estimates derived from the size class distributions, growth rates calculated from leaf production rates and leaf scar records, and fecundity estimates obtained from seedling densities. Matrix analyses suggested all 5 populations were stable under recent (1989) harvesting intensities; the dominant latent roots (X) of the five transition matrices ranged from 0.989 to 1.017. Elasticity analyses indicated that population stability was most sensitive to changes in survival probabilities of palms 10-15 m tall. Lambda values were relatively insensitive to changes in fecundity and growth. RESUMEN Matrizes de projeao de populacao foram usadas para pesquisar a estabilidade populacional de Iriartea deltoidea numa reserva extrativa no Estado do Acre, Brasil. A estrutura populacional destas palmeiras em 5 locais foi descrita usando distribuicoes de altura de classe; projeq6es foram baseadas em estimativas de probabilidade de sobrevivencia derivadas das distribuiK6es de tamanho de classe, indices de crescimento calculados de indices de producao de folhas e registros de cicatrizacao de folhas, e estimativas de fecundidade obtidas de densidades de mudas. As analises de matriz sugeriram que todas as 5 populao6es permaneciam estaveis debaixo de intensidades de colheita recentes (1989); as raizes latentees dominantes (X) das cinco matrizes de transiao variavam de 0.989 ate 1.017. Analises de elasticidade indicaram que a estabilidade populacional era mais sensivel as alteraoces de probabilidades de sobrevivencia em palmeiras com uma altura de 10-15 metros. Os valores lambda foram relativamente insensiveis a mudancas em fecundidade e crescimento.

Site Conditions Limit Pioneer Tree Recruitment After Logging of Dipterocarp Forests in Sabah, Malaysia'

In Sabah, Malaysia, logging operations leave substantial areas denuded of vegetation and topsoil. These sites are prone to erosion and slow to become reforested. Stands of pioneer trees established in these heavily disturbed sites may provide environmental conditions that foster recruitment of persistent forest species. Results of a field experiment indicate that recruitment of pioneer trees in recently logged sites is limited more by site conditions than by availability of seeds. In lightly disturbed areas, where the canopy is open and soils are uncompacted, seed addition does not increase the density of pioneer tree seedlings; resprouting vegetation covers such gaps within 3 mo following logging. On landings and skid trails, pioneer seedling densities increase initially following seed addition but by 12 mo after seeding, densities of pioneer seedlings are similar to those on unseeded areas. High seedling mortality in seed addition plots on skid trails and landings indicate that conditions on these compacted and nutrient poor sites during the first year after logging are unfavorable for the persistence of pioneer seedlings. On log landings, seedlings recruit adjacent to debris and bark fragments more frequently than expected by chance. Eighty percent of artificial seeds sown on landings and skid trails were washed away by overland water flow after three storms. The scattering of bark fragments and other small debris over denuded sites may assist seed capture and increase seedling survival temporarily, but many seedlings die within a year. Improving harvesting practices to minimize the area scraped and compacted by heavy machinery will be more effective management than attempting to rehabilitate these areas following logging. The broadcasting of seeds of pioneer trees onto landings and skid trails immediately after logging may be a reasonable management option for hastening tree cover in denuded areas, but only if it is combined with site preparations that improve conditions for the survival of pioneer tree seedlings.

Ecological characterization of tree species for guiding forest management decisions in seasonally dry forests in Lomerío, Bolivia

When the goal of natural forest management is to maintain the biodiversity and ecological integrity of the forest while harvesting timber, the silvicultural systems employed must promote timber production and reduce negative impacts on non-timber resources. To foster development of such a system in a seasonally dry tropical forest in Lomerio, Bolivia, we classified tree species according to their relative timber value, importance as food for vertebrate frugivores, and vulnerability to population declines when subjected to logging. We used this classification to identify a management system appropriate for the commercial species and to evaluate the compatibility of the system with the regeneration requirements of tree species that produce important food for mammalian wildlife. About half of the tree species in the site are commercially valuable for their timber and a similar proportion are considered of value as food for wildlife. A tree species rating for vulnerability to disturbance appeared to be independent of both timber and wildlife values. A silvicultural system that includes even-aged groups of trees within an uneven-aged matrix appears more suitable to the multiple goals of management in this forest than either an even-aged or uneven-aged (single tree selection) management system.

The influence of philosophical perspectives in integrative research: a conservation case study in the Cairngorms National Park

The benefits of increasing the contribution of the social sciences in the fields of environmental and conservation science disciplines are increasingly recognized. However, integration between the social and natural sciences has been limited, in part because of the barrier caused by major philosophical differences in the perspectives between these research areas. This paper aims to contribute to more effective interdisciplinary integration by explaining some of the philosophical views underpinning social research and how these views influence research methods and outcomes. We use a project investigating the motivation of volunteers working in an adaptive co-management project to eradicate American Mink from the Cairngorms National Park in Scotland as a case study to illustrate the impact of philosophical perspectives on research. Consideration of different perspectives promoted explicit reflection of the contributing researchers assumptions, and the implications of his or her perspectives on the outcomes of the research. We suggest a framework to assist conservation research projects by: (1) assisting formulation of research questions; (2) focusing dialogue between managers and researchers, making underlying worldviews explicit; and (3) helping researchers and managers improve longer-term strategies by helping identify overall goals and objectives and by identifying immediate research needs.

Forest canopy research: sampling problems, and some solutions

Conducting research in forest canopies is accompanied by both opportunities and difficulties. Opportunities occur because the canopy is important in overall forest structure and function, for example in containing a high proportion of species richness, being the site of forest-atmosphere fluxes, and in strongly influencing understory microclimate. However, despite this importance, the canopy has been largely neglected by researchers, until recently. Many difficulties in forest canopy research apparently arise from problems related to access. In a survey of 112 canopy researchers, examples of problems cited include: bias in the selection of study species or sampling locations; difficulties in obtaining adequate replication; problems in collecting data in a three-dimensional, complex environment; logistical constraints in moving between canopy sampling points; and, disturbance, sometimes including interference of the object being studied (i.e., ‘demonic intrusion’) caused by access. Many of these problems have at least partial solutions. These include: using multiple access techniques to give greater sampling flexibility; identifying appropriate units of replication within the canopy; using ground-operated canopy sampling methods; and, using protocols for unbiased and systematic data collection in three-dimensional sampling space. Designing experimental protocols for work in the canopy requires at the outset the allocation of time and resources for anticipating and overcoming the particular sampling problems associated with the work.

Monitoring Carbon Sequestration Benefits Associated with a Reduced-Impact Logging Project in Malaysia

The Reduced-Impact Logging Project, a pilot carbon offset project, was initiated in 1992 when a power company provided funds to a timber concessionaire to implement timber-harvesting guidelines in dipterocarp forest. The rationale for the offset is that when logging damage is reduced, more carbon is retained in living trees, and, because soil damage is minimized, forest productivity remains high. To estimate the carbon benefit associated with implementation of harvesting guidelines, a monitoring program was developed based on 1) field studies for measuring carbon stocks and flows; 2) a computer model of forest carbon dynamics for simulating various combinations of harvesting intensity and damage; and, 3) a projection model for calculating carbon balance over the project lifespan. Seventy-five percent of the carbon stored in this forest is in biomass, and of this, 59% is in large trees (>=60 cm diameter); consequently, reliable estimates of variables related to large trees are critical to the estimate of carbon benefits. Allometric methods for estimating belowground biomass are recommended over pit-sampling methods because of low cost-effectiveness of obtaining precise estimates of woody root biomass. Sensitivity analyses of variables used in the simulation model suggest that maintenance of ecosystem productivity has a large influence on long-term carbon storage in the forest. Projections of differences in carbon stores between the reduced-impact and conventional logging sites rely on assumptions about tree mortality, growth, and recruitment; published data for comparable sites in Malaysia are probably appropriate for estimating forest recovery from conventional but not reduced-impact logging. Continuing field work is expected to provide the data needed to evaluate assumptions of the models.

Defining and evaluating the impact of cross-disciplinary conservation research

Cross-disciplinary research is advocated as a way of improving understanding of the complexity of environmental problems; cross-disciplinary projects, centres and academic institutes have increased. However, there is confusion over the nature of cross-disciplinary research. Through review of papers defining themselves as cross-disciplinary that aim to address conservation problems, and by standardizing the definition of cross-disciplinary research, it is possible to evaluate the potential research impact on peers and practitioners. When papers were reclassified by authors, those reclassified as transdisciplinary were perceived to have a greater impact on practitioners, and those reclassified as non cross-disciplinary had the greatest impact on colleagues. Having clear definitions for types of cross-disciplinary research would help establish a firm foundation, not only for improving research quality, but also for evaluating research impact. While the number of cross-disciplinary studies is increasing, cross-disciplinary research falls short of integrating disciplinary methods in much depth and does not have much impact on participants outside of academia.

Closing the Feedback Loop? Iterative Feedback between Tutor and Student in Coursework Assessments.

We evaluate the case for using feedback iteratively, to improve student engagement and learning. In this model, students were invited to respond to tutor feedback with students’ own responses. Among the three courses/modules (three tutors) studied, differences in feedback styles were evident from: (a) thematic analysis of tutor comments and, for one course, and (b) comments in a student focus group. Students were inconsistent in their evaluation of tutor feedback but, in a more detailed study of one of the courses, there was clear evidence for the benefits of iterative feedback. Lessons from the main study were then applied to a course that had not previously incorporated iterative feedback. Using this experience, we provide suggestions for applying iterative feedback in assessments.