The role of non-timber forest products during agroecosystem shift in Xishuangbanna,southwestern China

There are few observations on the role of non-timber forest products (NTFPs) in shifting from subsistence to commercial plantation-dominated systems with long-term monitoring, despite interests in NTFPs for sustainable development and livelihood dependence. During 1998–2004, we conducted an annual survey of households in the two villages, Baka and Daka, which represent different stages in the shift from a subsistence agroecosystem to a rubber plantation-dominated system in Xishuangbanna, southwestern China. Significant negative correlations were observed between gross income and dependence on NTFPs-generated income in both Baka and Daka villages (P = 0.029 in Baka and P = 0.028 in Daka), which is supporting evidence that poorer households derive greater benefits from NTFPs than do wealthy households. When the rubber price dropped during 1998–2001, the NTFPs income of Baka increased greatly from US$59.10 to US$145 per household, or from 6.4% to 26.6% of household gross income. In contrast, in Daka village, NTFPs income increased by insignificant amounts of US$1.6 per household in 1998 to US$23.8 in 2001, but this was compensated by an increase in income from off-farm work of US$11 to US$147 (an increase from 1.8% to 16.2% of gross income per household) from 1998 to 2001 in Daka. NTFPs retained important roles both in alleviating risk associated with monoculture price fluctuations and in generating income for relatively poor people.     

Comparing the profiles,objectives and behaviours of new and longstanding non-industrial private forest owners in Quebec,Canada

Owing primarily to private forest owners' important role in supplying wood to the forest products industry, various studies have attempted to describe owners' profiles, objectives and behaviour. However, there have been few detailed examinations of the differences between the new generation of owners and the previous one. To better understand these differences, an analysis was carried out of data obtained from a telephone survey of a representative sample (n = 1723) of the 134,000 private forest owners in Quebec, Canada.The results reveal differences between the new (< 10 years of ownership) and longstanding forest owners (> 20 years of ownership) responding to the survey. In terms of owners' profiles, a number of variables differed significantly between the two categories of owners: education level, family income, way the first forest was acquired and the distance between the closest woodlot and the owner's place of residence. Differences in the two groups' objectives for owning a forest and for carrying out management work were also identified. Certain behaviours such as harvesting levels and sources of information consulted on forestry also differed significantly between the new and longstanding owners participating in the survey.In short, a shift is occurring towards owners who are from the professional class, are more highly educated and live farther away from their forests. The forest is integrated into these new owners' lifestyles in a different way since it is a leisure-time activity rather than part of their main occupation. The increasing diversity among owners will require a new approach by the agencies and associations offering them services and the government, which wants to encourage owners to harvest wood from their forests.     

Research in Non-Timber Forest Products

Abstract

Summary Non-timber forest products (NTFPs) have emerged as a complex set of issues reflecting changes in society and how natural resources are regarded. These issues range from the sustainability of forest management practices to the relationship of diverse cultures and communities to public lands and their resources. Research and its relationship to this set of issues is a relatively unknown aspect of NTFPs.

This paper reports on early NTFP research by scientists in the USDA Forest Service's Pacific Northwest Research Station. It characterizes efforts over approximately five years and identifies their key elements. It also discusses the role research has and could play in addressing the problems and questions associated with NTFPs and sustainable forestry .     

Life cycle inventories of roundwood production in northern Wisconsin: Inputs into an industrial forest carbon budget

Carbon budgets are developed to understand ecosystem dynamics and are increasingly being used to develop global change policy. Traditionally, forest carbon budgets have focused on the biological carbon cycle; however, it is important to include the industrial forest carbon cycle as well. The overall objective of this study was to quantify the major carbon fluxes associated with the production of Wisconsin's industrial roundwood, by using life cycle inventory (LCI) methodology to produce an industrial forest carbon budget. To achieve this objective we (1) developed carbon LCIs for the harvest process for three major forest ownerships (state, national, and private non-industrial), (2) developed carbon LCIs for a dimensional lumber and two oriented strand board (OSB) mills and (3) completed a scaled version of 1 and 2 to include more Wisconsin forestlands and to incorporate the other major processes within the industrial forest carbon cycle (e.g. primary mill, secondary mill, product use and product disposal processes of the industrial forest carbon cycle). The carbon budgets for the harvesting process of the Chequamegon-Nicolet National Forest (CNNF), the Northern Highland American Legion State Forest (NHAL), and the non-industrial private forests that participated in the managed forest laws of Wisconsin (MFL-NIPF) were 0.10, 0.18 and 0.11 tonnes C ha⁻¹ year⁻¹), respectively. The dimensional lumber and OSB products were both net carbon sources, and released 0.05–0.09 tonnes C/tonnes C processed). More carbon is sequestered than released within the industrial forest carbon cycle of Wisconsin's national (6 g C m⁻² year⁻¹), state (12 g C m⁻² year⁻¹) and non-industrial private forests (7 g C m⁻² year⁻¹). Using published net ecosystem production data we estimate that the net forest carbon cycle budget (sum of the biological and industrial C cycle, [Gower, S.T., 2003. Patterns and mechanisms of the forest carbon cycle. Ann. Rev. Environ. Resour. 28, 169–204]) for the CNNF ranges between −897 and 348 g C m⁻² year⁻¹. Life cycle inventories of wood and paper products should be clear and explicitly state what processes are included, so that results can be used by policy makers and future researchers.     

A financial analysis of rain forest silviculture in southwestern Sri Lanka

We examine the financial aspects of three silvicultural systems to encourage the sustainability of valuable hardwood species in mixed-dipterocarp forests of southwest Sri Lanka. We compare the net present value (NPV) of the current forest management approach (diameter limit harvests) with shelterwood harvests that promote light hardwood timber species. In this analysis, we also consider the potential of enrichment planting various precious timber (Diospyros quaesita — calamander), and non-timber forest product (NTFP) species (Caryota urens — fishtail palm; Elettaria cardamomum var. major — cardamom; Calamus zeylanicus — rattan) in conjunction with timber harvests. Two real (inflation adjusted) discount rates were used, 4 and 6%, respectively. Results show that when real discount rates are low (4%), and advance regeneration is present, NPV is highest for the one-cut shelterwood (US $9983 ha⁻¹). At a high discount rate (6%), reflecting the current short-term concession system and unstable rights to harvest, and where no advance regeneration was present, the diameter limit system (US $7173 ha⁻¹) was the optimum. On sites with advanced regeneration, the one-cut shelterwood system is clearly preferable. For all but rattan, shelterwood treatments provide higher NPVs for NTFPs than diameter limit cuttings primarily because of the higher light regimes and more growing space made available early in the rotation. The value for tea cultivation (US $26,000 ha⁻¹) far exceeds the value of managing these lands for timber alone, explaining the dramatic expansion in tea plantations on private lands. However, our results suggest that managing these lands for a combination of timber and enrichment plantings of NTFPs (US $23,000 ha⁻¹) can be comparable to tea plantations. By managing for NTFPs and timber, forest managers have new opportunities to solve the old problems of high-grading and land-use conversion.     

Natural disasters and economic development drive forest dynamics and transition in China

China has been implementing the world's most ambitious afforestation and forest conservation programs and undergoing rapid forest expansion since 1990s, thus, understanding the forest dynamics in China has global implications for sustainable forest management. Through analyzing forest area, biomass dynamics, and factors influencing deforestation and forest restoration, we found that the natural disasters and economic development drove forest dynamics and transition in China. The growth of the economy and population drove up demand for forest products, facilitating deforestation. The booming economy also boosted government's investment in forest restoration and conservation programs. Natural disasters damaged and frequently destroyed forests, but they also served as stimuli for the authorities to adopt remedy forestry policies and programs that ultimately led to forest increase. Nationwide, increasing peaks of annual afforestation were observed in the late 1950s, early 1980s, and early 2000s, and the newly increased area closed for forest restoration reached the peak in 1998. All these peaks were closely associated with peaks of natural disasters (i.e., floods, drought, and dust storm events). Based on the dynamics of forest area, biomass and forest consumption over the past 40 years, forest transition occurred during the late 1980s to the early 1990s, and it also strengthened the carbon (C) sink function of forests in China (with an increasing rate of 0.137 Pg C yr.⁻¹ during 1994–2008). Overall, our study highlighted the influences of natural disasters and economic development on the forestry policies and forest C dynamics in the newly industrialized country.     

Scenario analyses for the effects of harvesting intensity on development of forest resources,timber supply,carbon balance and biodiversity of Finnish forestry

We used national scenario analyses to examine the effects of harvesting intensity on the development of forest resources, timber supply, carbon balance, and biodiversity indicators of Finnish forestry in nine 10-year simulation periods (90-year simulation period) under the current climate. Data from the 11th National Forest Inventory of Finland were used to develop five even-flow harvesting scenarios for non-protected forests with the annual harvest ranging from 40 to 100 million m³. The results show that the highest annual even-flow harvest level, which did not decrease the growing stock volume over the 90-year simulation period, was 73 million m³. The total 90-year timber production, consisting of harvested volume and change in growing stock volume, was maximized when the annual harvest was 60 million m³. Volume increment increased for several decades when harvested volume was less than the current volume increment. The total carbon balance of forestry was the highest with low volume of harvested wood. Low harvested volume increased the values of biodiversity indicators, namely volume of deciduous trees, amount of deadwood and area of old forest.     

The economic impact of green-up constraints in the southeastern United States

Green-up, or adjacency, requirements are a common constraint in forestry. The American Forest and Paper Association has developed a Sustainable Forestry Initiative that includes a green-up constraint which limits the average clearcut opening to 48 ha for 3 years or until the average height of the regenerated trees is >1.4 m. In addition to constraining the average clearcut size, many forestry companies in the southeastern USA voluntarily limit their maximum clearcut size to between 60 and 90 ha. In this research, a heuristic algorithm was used to develop tactical forest plans that consider both the maximum and average clearcut sizes. Economic effects of the green-up constraints were estimated for situations where intensive management can reduce the length of the green-up time from 3 to 2 years on a 21 600 ha ownership in Georgia (USA). For a 60-ha maximum opening size, this reduction in green-up time from 3 to 2 years resulted in an additional US$ 66 600 in present net worth (PNW) over a 10-year analysis period. This corresponds to a US$ 10 per harvested ha, or a 0.8% increase in PNW. The benefit gained by reducing the length of the green-up period is less with a 90-ha maximum clearcut size, where PNW increases by US$ 45 600, or US$ 6.70 per harvested ha, a 0.5% increase. While the total volume per period was near the volume goal produced by a strategic forest plan, the spatial restrictions and the desire to maximize net present value resulted in lower volume of timber products (sawlogs and chip-and-saw logs) from older forest stands. A sensitivity analysis showed that an increase in price or yield further reduced the economic incentive for the reduction of the length of the green-up constraint. As price or volume decreased below expectations, however, the incentive to use intensive forest management practices to reduce the length of the green-up constraint became more attractive, since the differences between a 2-year and 3-year green-up time requirement may be large enough to pay for more intensive management practices.     

Estimation of biomass and net primary productivity of major planted forests in China based on forest inventory data

Reforestation and afforestation have been suggested as an important land use management in mitigating the increase in atmospheric CO₂ concentration under Kyoto Protocol of UN Framework Convention on climate change. Forest inventory data (FID) are important resources for understanding the dynamics of forest biomass, net primary productivity (NPP) and carbon cycling at landscape and regional scales. In this study, more than 300 data sets of biomass, volume, NPP and stand age for five planted forest types in China (Larix, Pinus tabulaeformis, Pinus massoniana, Cunninghamia lanceolata, Pouulus) from literatures were synthesized to develop regression equations between biomass and volume, and between NPP and biomass, and stand age. Based on the fourth FID (1989–1993), biomass and NPP of five planted forest types in China were estimated. The results showed that total biomass and total NPP of the five types of forest plantations were 2.81 Pg (1 Pg = 10¹⁵ g) and 235.65 Mg ha⁻¹ yr⁻¹ (1 Mg = 10⁶ g), respectively. The area-weighted mean biomass density (biomass) and NPP of different forest types varied from 44.43 (P. massoniana) to 146.05 Mg ha⁻¹ (P. tabulaeformis) and from 4.41 (P. massoniana) to 7.33 Mg ha⁻¹ yr⁻¹ (Populus), respectively. The biomass and NPP of the five planted forest types were not distributed evenly across different regions in China. Larix forests have the greatest variations in biomass and NPP, ranging from 2.7 to 135.37 Mg ha⁻¹ and 0.9 to 10.3 Mg ha⁻¹ yr⁻¹, respectively. However, biomass and NPP of Populus forests in different region varied less and they were approximately 50 Mg ha⁻¹ and 7–8 Mg ha⁻¹ yr⁻¹, respectively. The distribution pattern of biomass and NPP of different forest types closely related with stand ages and regions. The study provided not only with an estimation biomass and NPP of major planted forests in China but also with a useful methodology for estimating forest carbon storage at regional and global levels.     

Integration of forest inventory and satellite imagery:: a Canadian status assessment and research issues

Canada's ability to sustainably manage approximately 10% of the global forest cover is a critical environmental and economic issue. The capacity to meet such demands and to deliver on national and international commitments regarding forest management is enabled through collaboration between federal, provincial, and territorial agencies. A principal collaborator is the National Forest Inventory (NFI); a systematic photo-plot based monitoring system designed specifically for reporting purposes and as an important input for scientific models. Satellite imagery is illustrated here as a support data set to ensure the quality of the NFI, for auditing the photo-plot contents, and to detect spatial biases. The Canadian Forest Service, in collaboration with the Canadian Space Agency and other federal and provincial agencies, is producing a national land cover database of the forested area of Canada (Earth Observation for Sustainable Development of Forests (EOSD)) using Landsat-7 ETM+ data for circa 2000 conditions. The integration between the plot-based NFI with classified EOSD data is presented for central British Columbia, an area comprising 6 Landsat scenes and 324 2 km × 2 km photo-plots. Traditional accuracy assessment measures based on the analysis of coincidence matrices are reported as levels of agreement for hierarchically aggregated land cover categories (overall agreements of 91%, 79%, 64% and 26% for 3, 4, 6 and 20 classes respectively) to demonstrate coincidence between the different data products. Local agreement between NFI and EOSD is demonstrated as a means of photo-plot auditing while spatial biases are detected through investigations of geographic pattern in the coincidence values. The illustrated approaches may be expanded or applied to different mapped attributes (e.g., biomass) that are of utility to those attempting to characterize large areas in a consistent and rigorous fashion.     

Stand dynamics in a logged and silviculturally treated Costa Rican rain forest, 1988–1996

The lowland rain forests of Central America are poorly known from the standpoint of management for timber production. We studied the stand dynamics of a logged Costa Rican rain forest under three different regimes of post-logging silvicultural treatment. The site was located on low hills with Ultisols in Holdridge's Tropical Wet Forest life zone. The Pentaclethra macroloba-dominated forest had been high graded before planned management began. Management of the 540 × 540 m (29.2 ha) experimental area began with a timber harvest in the whole area during 1989–1990, 4 trees ha⁻¹ being cut overall for 10.1 m³ ha⁻¹. The experimental plots were 180 × 180 m (3.24 ha), comprising a 100 × 100 m (1.0 ha) central permanent sample plot (PSP) with a 40-m wide buffer strip. Two types of post-harvest silvicultural treatment: liberation/refinement (in 1991) and shelterwood (in 1992) were applied under a complete randomized block design with three replicates, using logged but untreated plots as controls. PSP data reported are for the 1988–1996 period for individuals with ≥10 cm DBH. The most marked changes in forest structure were caused by silvicultural treatment, basal area under the liberation/refinement treatment being reduced to ca. 65% of its probable mature forest value. Recruitment exceeded mortality in the years following intervention under all three treatments, but forest structural recovery was slowest under the liberation/refinement treatment. Post-intervention mortality rates appeared higher under the liberation/refinement treatment than under the control or shelterwood treatments, though differences were not statistically significant. In relation to tree attributes, mortality rates increased with decreasing DBH increment, crown illumination and quality of crown form. Commercial DBH increments were higher under the liberation/refinement treatment than in control plots during the 1993–1996 period. On the basis of its response to intervention during the first seven years of management, the forest appears resilient and productive; trends over time in mortality rates under the most intense silvicultural regime require close attention however. Pentaclethra-dominated forests are important components of the productive forest resources of Costa Rica and Nicaragua and, given current deforestation rates in areas such as southern Nicaragua, it is now urgent that the existing biophysical knowledge of these forests be applied to forest conservation and management.     

The role of government in operationalising markets for REDD + in Indonesia

The global climate initiative Reducing Emissions from Deforestation and Forest Degradation (REDD +) initially included carbon markets as one potential policy mechanism to finance a range of forestry projects in developing countries. Indonesia was an early leader on REDD +, and set up the regulatory frameworks and monitoring systems to support demonstration projects that could trade credits in voluntary carbon markets. This article applies a neoliberal governmentality framework to evaluate the development of REDD + market institutions in Indonesia during the Readiness period between 2008 and 2013. It critiques the role of the state in this process, and how the authority of public agencies shapes the actions of private subjects. The case of Indonesia indicates a pivotal role for government agencies at multiple levels in integrating the operation of REDD + market activities within a supportive regime of forest and land management. Critical to this process was legislation to trade in forest carbon and obtain project licenses, devolved land-use planning and forest management that could support commercial activities, and robust MRV surveillance systems to oversee on-ground activities. Despite these efforts, projects were often subject to an uncertain and highly contested forest management regime, undermining attempts to demonstrate the viability of operationalising market mechanisms at the local scale.     

A comprehensive analysis of teak plantation investment in Colombia

A financial assessment of forest investments is comprehensive if the analysis includes reliable yield estimates, land expectation value (LEV) and risk calculation. All of these aspects were considered and applied to teak plantations in Colombia, an emergent economy where high forest productivity, low opportunity cost of land, and decreased financial/economic risk have substantially contributed to promote forest investments. The von Bertalanffy non-linear mixed effect model was used to estimate forest yields using data collected from 31 permanent sample plots, measured over a 17 year period. A stochastic version of LEV along with other financial criteria was calculated by using a computer algorithm and Monte Carlo simulation. Finally, probabilities obtained from stochastic financial calculations were used in logistic models to estimate probabilities of success for a forest plantation project, a measure of risk assessment, after changing land prices. Results suggest that the potential forest productivity (i.e., the biological asymptote) ranges from 93 to 372 m³ ha^− 1. The mean annual increment is 27.8 m³ ha^− 1 year^− 1, which is attained 6 years after the forest plantation is established. Profitability analyses for teak plantations in Colombia suggest a LEV of US$7000 ha^− 1. The risk analyses indicate negligible financial risk for forestlands whose prices are lower than US$2000 ha^− 1.     

Valuation and characterization of the timber species in remnants of the Alto Uruguay River ecosystem,southern Brazil

Turvo Park in the Alto Uruguay River region of the State of Rio Grande do Sul is the last intact remnant of the Seasonally Deciduous Forest in southern Brazil. This forest once covered large parts of southern Brazil but it is now reduced to less than 3% of its original size due to intensive logging caused by its exceptional richness in tree species with commercial timber value. The current study presents results on the diversity of timber species inventored in Turvo Park and in a number of small and scattered forest remnants in its vicinity. All timber plants with DBH ≥5 cm were included in the forest inventory on 540 sampling points, established using the point-centred quarter method. On average, 313 plants ha⁻¹ were recorded, belonging to 57 different species from 25 families. Timber species of commercial value represented 64% of all woody species and 36% of all woody plants. Nectandra megapotamica and Apuleia leiocarpa were the main dominant species. Twenty percent of all plants showed a DBH greater than 40 cm, representing 67% of the total log volume. Differences in species diversity and plant density among the forest remnants were detected. The few forest remnants represent an enormous richness of timber species, being the maintainers and propagule repository for all the biodiversity of that ecosystem. A knowledge-based forest management plan is therefore required to secure their vital role in forest enrichment programs or in projects aiming at recovering abandoned and degraded areas, and in breeding programs for the timber production improvement.     

Changing Consumption and Marketing pattern of Non-timber Forest Products in a Competitive World: case Study from an Urban Area of North-eastern Bangladesh

In the last decade non-timber forest products (NTFPs) and their associated goods have received much attention from researchers and development workers for their perceived socio-economic importance and potential, particularly in developing countries. It has been increasingly recognized that promoting the use, production and sustainable harvesting of such kinds of products could also contribute to forest conservation in the long run. However, since the development process has progressed in most regions, alternatives or substitutes of such products have become available on the markets, and it will be difficult for these nature-based products to exist without additional product values. A market survey was conducted in an urban fringe of north-eastern Bangladesh to investigate NTFP-based product diversity, and marketing patterns and challenges. Further information was collected from sellers and consumers to understand their views on probable future strategies to sustain the markets of these products. A total of 38 NTFP and NTFP-based secondary products were recorded from 25 NTFP shops, including 16 permanent, 7 temporary (or semi-permanent) and 2 mobile shops. The greatest demand was observed for bamboo and cane-based products, for which supply suffered due to the scarcity of raw materials. A decreasing trend in the consumption of NTFP-based articles for urban domestic use was also reported from the sellers. To cope with the competitive markets, sellers were found to place more emphasis on creative marketing, durability and appearance of their products. The study concluded that active government support is needed for the sustenance of this industry in a changing global perspective. This could be in the form of technical advancement in the production process, improvement of existing product supply chains and skill development of the workers which will not only secure the future of these products but also provide an essential means for the survival of this industry and for thousands of people living from it.     

A Collaborative Forest Management user group's perceptions and expectations on REDD + in Nepal

Although local communities and indigenous peoples are the main actors for REDD + practices, their needs and perceptions have received little attention in the debates on REDD +, despite much rhetoric to the contrary. In this study, a Collaborative Forest Management (CFM) site was studied using a questionnaire survey administered to a CFM user group in order to understand CFM users' perceptions and knowledge of their forest and REDD + and evaluate their expectations for potential REDD + benefits. Specifically, the study investigated the following questions: Do CFM users know about REDD +? Are there any differences in the perceptions and expectations among nearby and distant users?The data obtained from the semi-structured questionnaire, interviews and household survey indicate that people are sensitive to changes in climate and the forest around them but are unaware of climate change mechanisms and the links between climate change and deforestation. Compared to distant users, nearby users felt more strongly that the forest is essential to their lives and were more interested in participation in REDD + practices. As the distant users are also significant actors in management practices, there is a need to raise distant users' interests in REDD +. Both nearby and distant users had high expectations of the potential benefits of REDD +. These findings are significant for policymakers as they provide insights into the feasibility of REDD + within the context of the present form of CFM in Nepal. The Government and related stakeholders should communicate with the local communities regarding the opportunities and risks of REDD + projects, and meaningfully involve the local communities in the design and implementation process if they are to receive local support. It is important to develop a system of equitable decision-making and benefit-sharing that reflects local needs, and is incorporated into any REDD + action plans applied to the Terai forests.     

Prospects and challenges of tenure and forest governance reform in the context of REDD + initiatives in Nepal

This paper argues that the Reducing Emission from Deforestation and Forest Degradation (REDD +) initiatives in Nepal have not adequately understood and considered institutional and political issues around forest tenure and governance challenges. The paper is developed based on reviews of polices, assessments of project activities, interviews with key informants, and observation of ongoing REDD + related public discussions. We found that the REDD + initiatives so far appear to have prioritized technical issues such as carbon assessment, reference scenario, and measurement, reporting and verification of emissions. However, a major policy challenge in Nepal is the substantial deforestation and degradation going on, which leads to substantial challenges of leakage and threatens Nepal's National REDD + policy ambition. The key drivers of deforestation and degradation in Nepal are still poorly identified, analyzed and understood. Inadequate focus of Nepal's present REDD + readiness on the core issues of contested forest tenure and frail governance entails that an unrealistic policy and institutional measures would be developed in addressing these issues of deforestation and degradation. Consequently, it would seriously undermine the prospect of achieving emission reduction — the very goal of REDD +. It is suggested that a robust analysis, collective understanding and broadly agreed policy measures for curbing deforestation must be at the core of REDD + readiness process.     

Tree and forest encroachment into fescue grasslands on the Cypress Hills plateau,southeast Alberta,Canada

Tree encroachment into rough fescue (Festuca campestris) grassland has been identified as an ecological concern on the Cypress Hills plateau in southeastern Alberta, Canada. A combination of field sampling (109 transects), a dendrochronological assessment (1361 trees), and a time series analysis of remotely sensed images from five different time periods (1950–2002) were used to determine the extent and rate of tree encroachment and forest development. Tree cover increased by 768 ha (～51%) between 1950 and 2007, representing 10% of the study area, from 1502 ha of pre-1950 forest. Post-1950 tree invasion also created an ingress zone of 750 ha (～10% of study area) based on field transects. Forest cover increased at a consistent rate of 14.3 ha/year. Lodgepole pine (Pinus contorta var. latifolia) was the most common tree species associated with encroachment. Invasion based on the number of established trees occurred at an exponential rate of 3.1%/year after 1890, with density increased by filling spaces adjacent to and between trees within the grassland vegetation. The rate of tree establishment increased to 4.4%/year after 1980, suggesting a change occurred in environmental conditions. Annual atmospheric temperatures increased 0.55 °C from 1929 to 2005 (P < 0.001), with winter (December–February) and spring (March–May) temperatures accounting for most of the increase (P < 0.001), whereas summer (June–August) temperatures slightly decreased (P < 0.050, 0.34 °C) and precipitation increased (P < 0.005, 30 mm). Cattle and elk (Cervus elaphus) grazing was not considered a primary factor for explaining tree encroachment. Based on multidimensional scaling, lodgepole pine establishment was associated with warmer spring temperatures and greater fall (October–November) precipitation. A landscape devoid of wildfires, combined with greater moisture availability, and a longer frost-free season is likely conducive to the sustained establishment of coniferous trees and forest development within the Cypress Hills fescue grassland ecosystem. Long-term conservation of the fescue grasslands could be possible by reintroducing fire.     

Diameter increment patterns among 106 tree species in a logged and silviculturally treated Costa Rican rain forest

Studies of growth rates of trees in managed neotropical forests have rarely employed complete botanical identification of all species, while published information for Central American lowland rain forests largely concerns forests free of recent disturbance. We studied diameter increments of trees in a managed Costa Rican rain forest. The Pentaclethra macroloba-dominated forest was located on low hills with Ultisols in Holdridge's Tropical Wet Forest life zone. The 540 m × 540 m (29.2 ha) experimental area was lightly logged during 1989–1990. The 180 m × 180 m (3.24 ha) experimental plots comprised a 100 m × 100 m (1.0 ha) central permanent sample plot (PSP) with a 40-m wide buffer strip. Post-harvest silvicultural treatments were liberation/refinement (in 1991) and shelterwood (in 1992), applied under a complete randomized block design with three replicates, using logged but untreated plots as controls. All live trees ≥10 cm DBH in the PSPs, were identified to species; data reported are for 1993–1996. Cluster analysis was used to group species on the basis of the median and quartiles of their diameter increment distributions, separating data by silvicultural treatments; five diameter increment groups were established and subdivided on the basis of the adult height of each species (four categories), giving 17 species groups in the final classification. Adult height and silvicultural treatment made a significant contribution to growth rate variation. Median annual increments of the slowest-growing species groups, which featured many under- and middle story species, were ca. 1 mm; those for the fastest growing species, which were mainly canopy and emergents, were ca. 16 mm. All species in the groups of very fast growth were pioneers, whether short or long-lived, though many other pioneer species did not show fast growth. The proportions of species found in groups of moderate, fast or very fast growth were greater in the silviculturally treated plots than in the controls, and one complete diameter increment group, of fast growth, was only represented in the treated plots. Crown form, crown illumination and presence of lianas in the crown, showed significant correlations with diameter increments, though the importance of these latter two variables varied with silvicultural treatment. The very fast growth groups differed from the others in having higher proportions of trees with well-formed, well-illuminated crowns and an irregular diameter distribution with relatively few individuals in the smallest DBH class. Comparison with data from other neotropical forest sites shows that long-lived pioneers such as Vochysia ferruginea and Jacaranda copaia grow fast or very fast at all sites, while non-commercial canopy and emergent species of Chrysobalanaceae and Sapotaceae appear to be uniformly slow-growing. Growth data for the majority of species are, however, published for the first time.