Population dynamics and management of Amazon tidal floodplain forests: Links to the past, present and future

Although tidal floodplain forests represent the oldest commercial logging frontier in the Amazon, tree demography analyses are lacking. Consequently, the accurate evaluation of impacts of past use and the development of ecologically sound forest management has lagged. To address that gap, we combine matrix model methods with data from interviews with tidal floodplain smallholders regarding land use and ecological knowledge. Here we examine the population dynamics of 8 common tidal floodplain species and explore the link between species population ecology and past, present, and future timber use.Despite the generally high timber stocks due to the dominance of Mora paraensis, these tidal floodplain forests offer challenges to management similar to those seen in tropical forests elsewhere, including low recruitment and species-specific tree growth rates, population densities and size distributions. Furthermore, species population ecology and survey results indicate that the long legacy of forest use in the tidal floodplain forests will influence the future of forest use and management, negatively impacting some species (e.g., Virola surinamensis) while likely benefiting others (e.g., M. paraensis). The observed diameter distributions of species least harvested in the past (e.g., M. paraensis, Licania heteromorpha) follow those derived from stable stage distributions. For other historically harvested species (e.g., Carapa guianensis, V. surinamensis), a larger number of harvest-sized trees for most species would be expected under unlogged conditions, a result corroborated by survey results indicating that maximum log size of long-used timber species has decreased over the past decades.While timber extraction in the Amazon Estuary has endured for centuries, our results suggest long-term timber use does not necessarily entail sustainability; a long history of timber harvesting can also indicate a gradual process of resource depletion as preferred species are sequentially exhausted. If current practices are left unchanged, the prospects for long-term management are likely to decrease further as the densities of preferred high-value species (C. guianensis, V. surinamensis, P. filipes) fall to levels that make management economically unattractive.     

Effects of liana load,tree diameter and distances between conspecifics on seed production in tropical timber trees

Seed production in tropical timber trees is limited by abiotic resources, pollination and pre-dispersal seed predation. Resource availability is influenced by the number of competing trees and by lianas that often reach high densities in disturbed parts of tropical forests. The distance between conspecific trees affects pollination efficiency and seed predation intensity, and may therefore indirectly affect the long-term sustainability of selective logging. Here we investigate how reproductive status and the number of seeds dispersed per tree are affected by liana load, distance to the nearest conspecifics, number of competing neighbours and tree diameter in the timber trees Cariniana ianeirensis and Terminalia oblonga. The study is based on a large-scale silvicultural experiment in lowland Bolivia. We found that the reproductive status of the two species was negatively correlated with liana cover and positively with tree diameter. In C. ianeirensis the most liana-infested trees dispersed fewer seeds. In T. oblonga the intensity of pre-dispersal seed predation decreased with distance to the nearest conspecifics. There was no evidence that seed viability or seed production decreased with distance to nearest conspecifics in either species as would be expected if isolation resulted in increased self-pollination. Our results indicate that reproduction can be severely reduced in timber trees if the largest, most healthy and least liana-covered trees are logged, but that liana cutting on the remaining seed trees can considerably improve seed production. In some species seed production may be further improved by ensuring that seed trees are located far apart.     

How rare is too rare to harvest?: Management challenges posed by timber species occurring at low densities in the Brazilian Amazon

Tropical forests are characterized by diverse assemblages of plant and animal species compared to temperate forests. Corollary to this general rule is that most tree species, whether valued for timber or not, occur at low densities (<1 adult tree ha⁻¹) or may be locally rare. In the Brazilian Amazon, many of the most highly valued timber species occur at extremely low densities yet are intensively harvested with little regard for impacts on population structures and dynamics. These include big-leaf mahogany (Swietenia macrophylla), ipê (Tabebuia serratifolia and Tabebuia impetiginosa), jatobá (Hymenaea courbaril), and freijó cinza (Cordia goeldiana). Brazilian forest regulations prohibit harvests of species that meet the legal definition of rare – fewer than three trees per 100 ha – but treat all species populations exceeding this density threshold equally. In this paper we simulate logging impacts on a group of timber species occurring at low densities that are widely distributed across eastern and southern Amazonia, based on field data collected at four research sites since 1997, asking: under current Brazilian forest legislation, what are the prospects for second harvests on 30-year cutting cycles given observed population structures, growth, and mortality rates? Ecologically ‘rare’ species constitute majorities in commercial species assemblages in all but one of the seven large-scale inventories we analyzed from sites spanning the Amazon (range 49–100% of total commercial species). Although densities of only six of 37 study species populations met the Brazilian legal definition of a rare species, timber stocks of five of the six timber species declined substantially at all sites between first and second harvests in simulations based on legally allowable harvest intensities. Reducing species-level harvest intensity by increasing minimum felling diameters or increasing seed tree retention levels improved prospects for second harvests of those populations with a relatively high proportion of submerchantable stems, but did not dramatically improve projections for populations with relatively flat diameter distributions. We argue that restrictions on logging very low-density timber tree populations, such as the current Brazilian standard, provide inadequate minimum protection for vulnerable species. Population declines, even if reduced-impact logging (RIL) is eventually adopted uniformly, can be anticipated for a large pool of high-value timber species unless harvest intensities are adapted to timber species population ecology, and silvicultural treatments are adopted to remedy poor natural stocking in logged stands.     

Analysis of the changes in forest ecosystem functions,structure and composition in the Black Sea region of Turkey

We used geographical information system to analyze changes in forest ecosystem functions, structure and composition in a typical department of forest management area consisting of four forest management planning units in Turkey. To assess these effects over a 25 year period we compiled data from three forest management plans that were made in 1986, 2001 and 2011. Temporal changes in forest ecosystem functions were estimated based on the three pillars of forest sustainability: economics, ecology and socio-culture. We assessed a few indicators such as land-use and forest cover, forest types, tree species, development stage, stand age classes, crown closure, growing stock and its increment, and timber biomass. The results of the case study suggested a shift in forest values away from economic values toward ecological and socio-cultural values over last two planning periods. Forest ecosystem structure improved, due mainly to increasing forest area, decreasing non-forest areas (especially in settlement and agricultural areas), forestation on forest openings, rehabilitation of degraded forests, conversion of even-aged forests to uneven-aged forests and conversion of coppice forests to high forests with greater growing stock increments. There were also favorable changes in forest management planning approaches.     

<Emphasis Type="Italic">Mangifera sylvatica</Emphasis> Roxb. in the Forests of South-Eastern Bangladesh: A Potential Underutilised Tree for Small-Scale Forestry

Mangifera sylvatica Roxb. is an underutilized wild tree species valued for its fruit, timber and medicine. It was believed to be widely grown in sub-tropical forests of Bangladesh, but nowadays can be seen only sparsely. Even though it has multiple uses, only the indigenous people in hilly areas use the fruit of this species, for cooking and making pickles. This study was designed to (1) observe the population status of M. sylvatica in the forests of south-eastern Bangladesh, (2) evaluate domestication potentiality through seed germination and early growth of seedlings, and (3) assess its suitability for small-scale forestry. Through 16 field visits in eight forest beats, 66 individual trees were identified and their GPS (global positioning system) coordinates were recorded. A seed germination rate of 83 % at 6 weeks after direct sowing was attained. The early growth of seedlings with fertilizer treatments showed no remarkable difference with seedlings without fertilization. The seed germination rate and early growth of seedlings indicates that this species can be easily domesticated and be incorporated into small-scale plantation programs. In that it has multiple use values, this species warrants promotion in small-scale forestry programs for conservation and benefiting the villagers.     

Forest Structure Under Different Management Regimes in the Western Lowlands of Nepal

ABSTRACT

For landscape level conservation and rural sustenance, forests outside of protected areas are becoming increasingly important. Since most outside forests in the lowlands of Nepal are under government control and utilized as open access resources, their feasibility to achieve these objectives is questionable. We compared forests inside (with three decades of strict protection) and outside of protected areas (under government control and proposed as community forests) to assess the ecological sustainability of outside forests and to provide baseline data on structure of outside forests so that effectiveness of community forestry (after implementation) can be evaluated in the future. Our results indicate that outside forests were in a degraded condition with low tree, sapling and seedling densities and lower species diversity. Trees in lower dbh (diameter at breast height) classes were absent in these forests. Although the canopy layer was not significantly different, the ordination of plots and species showed that species composition of understory and the ground layer were different than protected forests. The present condition of outside forests is not only ecologically unsustainable but also cannot fulfill the demands for forest products of local people. The inefficiency of government to monitor against exploitation has been responsible for present conditions. We recommend that community forestry programs, which are successful in improving conditions of degraded forests in the mountains of Nepal, should be widely implemented in lowland areas (Terai) and proposed community forests should be handed over to local communities as soon as it is practicable.     

The sustainability of selection cutting in a late successional broadleaved community forest in Bhutan

This study assessed the sustainability of selection cutting in a community forest (CF) in Bhutan. The harvesting approach differed from cable crane logging operations in an adjacent commercially managed forest by creating much smaller canopy openings. This had many implications for natural regeneration of preferred species. The study was conducted in a late successional broadleaved CF containing 32 genera of tree species dominated by Quercus and Castanopsis and managed for timber, firewood, non-wood forest products and forest grazing. The study was based on a comparison of two forest inventories to assess forest structure and regeneration, a study of stumps to quantify harvesting intensities, and a household survey to quantify livestock holdings and grazing patterns. The study examined different intensities of selection cutting in three blocks of the CF and found that higher intensities of selection cutting did not have a negative impact on: (a) natural regeneration of seedlings and saplings of preferred timber species; (b) the diameter distribution of all species and use categories except for Quercus; (c) the diversity of tree genera; and (d) the percentage of remaining trees with favorable bole shape and form. These results contrasted with findings in the adjacent commercially managed forest. Community management of broadleaved forests with selection cutting appeared to be sustainable and avoid some of the unresolved silvicultural problems associated with commercially managed forests in Bhutan. However more research is needed on the sustainable management of Quercus spp.     

Regeneration of Fitzroya cupressoides after indigenous and non-indigenous timber harvesting in southern Chilean forests

Fitzroya cupressoides (Cupressaceae) is an endemic and long-lived conifer of southern Chile and Argentina (40–43° S). This species has been subject to continuous exploitation since the 16th century, causing extensive population decline. Historically, the main labour force for the exploitation of F. cupressoides (alerce) was the indigenous Mapuche-Huilliche population, first under the command of the Spanish settlers and later, of non-indigenous Chileans. In coastal forests, timber of alerce has been harvested by Huilliche communities as well as by Chilean and international forestry companies. Records of the regeneration of this pioneer tree after exploitation in the Andean mountains have generally shown limited regeneration depending on the intensity of harvest. Because indigenous exploitation does not use machinery for timber harvesting, and is supposedly less utilitarian than commercial harvest, I propose that areas in the Coastal Range harvested by Huilliche communities should present higher regeneration of alerce than areas harvested by forestry companies. To test this hypothesis, I sampled 10 stands harvested and abandoned by forestry companies and 10 stands harvested by Huilliche communities in the coastal range of the Osorno Province (41° S, 400–800 m). In each stand, I estimated the density of regeneration (sapling stage), number of stumps, number of live adults, and the number of standing and fallen dead alerce. Each stand was characterized by elevation, forest-type, incidence of fire, and vegetation cover. Results showed that forests harvested by Huilliches had higher numbers of live, remnant adult trees with a dbh ≥ 60 cm than forests harvested by timber companies. The number of stumps with a dbh ≥60 cm was significantly higher in stands harvested by timber companies than in Huilliche stands. Despite large differences in sapling densities among stands, regeneration density of alerce was unrelated to the type of harvest used by indigenous people or forestry companies.     

Tree Species Diversity in Community Managed and National Park Forests in the Mid-Hills of Central Nepal

Community forestry is expanding in developing countries but there is limited knowledge of, and contradictory findings about, its contribution to biodiversity conservation. This study aims at increasing the understanding of tree species diversity in community forests compared to National Parks. A forest inventory was carried out in four community forests and one National Park in the mid-hills of central Nepal. The study found that community forestry has contributed to high tree species diversity where forest management communities have interests in multiple species, but most community forests are moving toward promoting limited timber yielding species that have high economic value. Linking community forestry with economic incentives for conserving multiple tree species could therefore be a strategy to conserve biodiversity outside of protected areas.     

Contributions of root and stump sprouts to natural regeneration of a logged tropical dry forest in Bolivia

A major impediment to the sustainable management of tropical dry forests in Bolivia is the scarcity of natural regeneration of commercial timber tree species. Where regeneration is present, true seedlings of many species are outnumbered by vegetative sprouts from roots, broken stems, and the stumps of felled trees. This study evaluates the importance of resprouts promoted by logging operations for the regeneration of commercially important canopy tree species. The objectives of the study were: (1) to characterize stump and root sprouting behaviors of canopy tree species harvested for timber; (2) to quantify the effect of logging on relative abundances and growth rates of stump sprouts, root sprouts, and true seedlings; (3) to relate the species-specific probabilities of stump sprouting to stump diameter and stump height; and (4) to explore how sprouting varies with the ecological requirements of canopy tree species. The study was carried out 1–5 years after logging of a privately owned land in a Bolivian tropical dry forest. Twenty-seven of the 31 species monitored resprouted at least occasionally, among which Centrolobium microchaete (Leguminosae-Fabaceae) and Zeyheria tuberculosa (Bignoniaceae) were the most frequent stump sprouters, and Acosmium cardenasii (Leguminosae-Fabaceae) and C. microchaete were the most frequent root sprouters. In all species the number of sprouts declined with increasing stump diameter and stump height. The probability of stump resprouting differed among species but did not vary consistently with stump diameter, except in Z. tuberculosa in which it declined. Approximately 45% of juveniles <2 m tall of canopy tree species originated from root or stem sprouts. Light-demanding species tended to regenerate more from seeds and root sprouts than from stumps. Seedling densities were higher in microsites opened by logging, while root and stem sprouts were equally common across microsites. Given their abundance and the fact that root and stem sprouts at least initially grew faster than true seedlings, we conclude that vegetative regeneration in this tropical dry forest is an important mode of post-logging regeneration especially for species that regenerate poorly from seed. Resprout management should be considered as a potentially effective strategy for the procurement of regeneration following logging, especially for species that do not readily recruit from seed.     

The Management of Small Diameter,Lesser-Known Hardwood Species as Polewood in Forest Communities of Central Quintana Roo,Mexico

ABSTRACT

Diversification in resource management can serve as a strategy to increase both economic well-being and environmental sustainability in rural communities, especially in tropical forested regions. This paper documents and analyzes the recent and rapid regional commercialization of small diameter, lesser-known tropical hardwood species as polewood in Quintana Roo, Mexico, presenting the promises and perils for sustainable management and resource diversification in the context of Mexican economic development and community forestry. We present data from interviews with local farmers and forestry officials involved in community management of timber resources to reveal baseline information regarding the use and management of polewood, locally called palizada. We found the same permitting system used for high-value timber was implemented for polewood without recognizing the complex ecological characteristics of polewood and the different metrics by which polewood and high-value timber are bought and sold. These factors, coupled with an unstable market for this new forest product and potential for overexploitation, present a difficult situation for the sustainable management of polewood. We conclude that incorporating local ecological knowledge in devising polewood management strategies can strengthen local governance and is an essential aspect of managing this emerging market of forest products.     

关于保护和发展我国森林的思考

作者认为保护和发展我国森林的根本指导思想和理论基础是森林生态经济系统思想和森林生态经济学理论。本文还就林业发展方向、林业生态工程项目、工业用材林和薪炭林营造、资源综合高效利用,以及加强山区现有天然林的保护提出了具体看法。     

Timber management with variable retention in Nothofagus pumilio forests of Southern Patagonia

Forestry practices integrating ecological and social criteria have been replacing those based only on economic values. Traditional silviculture, such as shelterwood cuts (SC), transforms uneven-aged original stands to an even-aged managed forest. Recently, other methods have proposed to conserve some of the original heterogeneity of the old-growth forests. One proposal leaves 30% of the timber quality forest area as aggregated retention and 20% basal area as dispersed retention. The aim of this study was to analyze the feasibility of timber management with aggregated and dispersed retention in Nothofagus pumilio old-growth forests by analyzing timber and harvesting yield potential compared with traditional regeneration systems. Also, remnant tree stability of aggregated retention was analyzed.     

European aspen (Populus tremula L.): a review with particular reference to Scotland II. Values, silviculture and utilization

Interest in European aspen (Populus tremula L.) has increasedin recent years as a result of efforts to restore and extendnative woodland, and to diversify the range of species usedin forestry plantations. Aspen is a straightforward tree tomanage; it is of considerable ecological value and capable ofproducing utilizable timber. Planting of aspen in native woodlandis currently limited by a shortage of plants of Scottish origin.Propagation from seed, whilst possible, has not been practised,and recent efforts to produce stock have concentrated on vegetativemeans. The use of aspen as a component of plantation forestrycould be increased on appropriate sites; it is an excellentamenity species and its timber is currently acceptable as chipwoodand could complement the production of poplar timber in thelowlands. However, on the basis of limited data, growth ratesand stem form of aspen in Scotland appear to be rather poorerthan on the European continent where aspen is a significanttimber producing species. More would also need to be known aboutits susceptibility to disease before its timber production potentialcould be evaluated properly.     

森林生态系统管理科学——21世纪森林科学的核心

在阐述森林在全球生态环境中的地位和国内外人工林经营的教训基础上,论证了实行森林生态系统管理的必要性,并提出了实施方案.作者认为应以森林生态学的基本原理和方法为指导,结合一系列现代科学技术,从森林生态系统与环境条件的关系和树木生长的生理生态学机制出发,根据森林生态系统的结构功能规律,对系统进行诊断,从而制定出相应的生态系统管理措施,以实现森林生态系统的持续稳定和高生产力,使其既具有良好生态防护功能,又能长期地为国民经济建设提供更多木材资源.     

森林认证的现状与发展趋势

森林认证出现于20世纪90年代初,10年来,森林认证在全球范围内取得了快速的发展。文中介绍了森林认证的起源和发展现状,指出了森林认证的发展趋势,并对我国开展森林认证提出了建议。     

Population dynamic and management of <Emphasis Type="Italic">Pinus oocarpa</Emphasis> and <Emphasis Type="Italic">Tabebuia rosea</Emphasis> within silvopastoral systems in Central America

Silvopastoral systems—the management of trees within pastures from natural regeneration or planting—are a strategy to promote sustainable livestock systems and ecosystems services. Timber is one of the products from these systems with potential to increase family revenues. The management of natural regeneration and population dynamics of trees is a feasible way to harvest timber and maintain environmental services. In this research, we modeled the population dynamics of Pinus oocarpa and Tabebuia rosea, two important timber species of silvopastoral systems in Central America. The results showed that farmers manage a significant density of different tree species from natural regeneration. However, only the species with well-known uses or desired services are allowed to remain. The natural regeneration is more impressive in silvopastoral systems with natural grass than those with exotic grass. Farming practices, for instance use of fire for weed control, are the main reasons for low rates of natural regeneration in pastures with exotic grass. The models of population dynamics for both species showed that the sustainable timber harvest plans are a viable activity in pasturelands under natural-regeneration management plans. Innovative farmers are willing to adopt silvicultural practices and management of population dynamics to increase timber revenues and sustainability if forestry regulations for sustainable use of trees in farms are simplified.     

Structure and composition of the seed bank in monospecific and tree species-rich temperate broad-leaved forests

How tree species diversity affects ecosystem functioning is a topic of intensive research. This study compares monospecific and species-rich broad-leaved forests under similar bedrock and climate conditions for the size and composition of their seed bank. We tested the hypotheses that (i) the actual herb-layer vegetation has an only weak influence on the composition of the seed bank, (ii) the species diversity of the seed bank increases with tree-layer diversity, and (iii) tree species forming a more persistent litter layer reduce the number of germinating seeds. The number of seeds and their species composition were investigated in soil cores taken from three soil depths (0–5, 5–10 and 10–20 cm; n = 4, with each 6 sub-samples) in 9 study plots differing in tree species diversity (3 monospecific Fagus plots, 3 plots with Fagus, Fraxinus and Tilia, and 3 plots with Fagus, Fraxinus, Tilia, Carpinus and Acer). Tree species diversity had a much stronger influence on the size and composition of the seed bank than herb-layer diversity or composition, the latter revealing only a low similarity to the corresponding seed bank. The number and species diversity of emerging seedlings decreased significantly with the amount of acidifying Fagus litter, but increased with litter mass of Tilia and other trees with nutrient-rich, rapidly decomposing litter. We conclude that tree species diversity does not influence the seed bank through effects on herb-layer composition, but mostly through differential disturbance histories of the stands and litter quality effects on germination and soil chemistry. From the contrasting effects of Fagus and Tilia leaf litter, it appears that effects of tree species identity are more relevant than influences of tree species diversity itself.     

Regeneration patterns of Eastern white pine (Pinus strobus L.) in hardwood-dominated forests in Virginia, USA

Eastern white pine (Pinus strobus L.) is a moderately shade-tolerant species that co-occurs with hardwood tree species in many forests of the eastern United States, as well as in pure stands. The species is valued for its timber, as well as for wildlife and recreation. Regeneration of this species is somewhat unpredictable and often occurs in patches of similarly-aged cohorts. We described the regeneration patterns of this species and examined their relation to environmental variables within hardwood forests of southwestern Virginia, USA. An average of 5.3 white pine patches per ha were observed in this study. The majority of patches consisted of saplings (85%), with 9% of patches in pole size classes, and 6% in seedling size classes. The average density of patches was 43.5 stems with an average age of 20 years. The size of patches averaged 80.6 m². The total density of seedlings and the number of regeneration patches of all sizes of regeneration (seedlings, saplings, and poles) in plots was related to the surrounding density of large white pine trees (potential seed trees). The density of seedlings or patches was not significantly related to current vegetation cover or soil surface cover variables, but more than half of regeneration patches were located in or adjacent to old canopy gaps, most of which were old logging gaps. While seedling regeneration may occur within the understory of these forests near seed trees, advancement to the sapling and pole stage appears to be associated with canopy gap formation.