The ecological sustainability of tropical forest management: evaluation of the national forest management standards of Costa Rica and Nicaragua, with emphasis on the need for adaptive management

From a conceptual point of view, national forest management standards in Latin American countries have progressed significantly in recent years. Examples include the Costa Rican Standards and Procedures for Sustainable Forest Management and Certification, developed by the National Commission for Forest Certification and in Nicaragua, the National Institute of Forestry proposal of principles, criteria and indicators for sustainable forest management. In line with general approaches worldwide, these national standards primarily focus on the fulfillment of sound forest practice. There is comparatively little emphasis on the assessment of management outcomes or changes in key components of the eco- and social-systems that result from management impacts. Essentially, there is little emphasis on adaptive management, though arguments that management cannot be sustainable if it is not adaptive are persuasive. This study sought to contribute to the development of standards that include elements for adaptive management that define, communicate and evaluate sustainable forest management in Costa Rica and Nicaragua. Elements from the national standards and the CIFOR generic C&I template (predominantly focused on forest management outcomes) were used as a starting point. The basic research process consisted of three phases of evaluation (in-office, desk and field). The evaluations were carried out by multidisciplinary, international groups of experts in forest ecology, management and policy. This study demonstrated the value of forums and workshops that facilitate exchange between forest scientists and policymakers; the innovation and application of a practical, applicable and scientifically based methodology for developing national level C&I; and acceptance of this methodology by key players in the fields of forest management and policy. These experiences and the resulting proposals of C&I for the evaluation of ecologically sustainable forest management are expected to be used as points of reference for future development of forest policy in Costa Rica and Nicaragua, and to contribute to the overall understanding of C&I development processes in the region.     

Population structure of Carapa guianensis in two forest types in the southwestern Brazilian Amazon

Carapa guianensis Aublet. is a tropical tree with strong multiple-use characteristics, and is valued for both the high quality oil extracted from its seeds and as a timber resource. This study compares the population structure of this economically important rainforest tree in two contrasting forest types: occasionally inundated and terra firme forests. Main study objectives were (a) to assess the density, spatial distribution, and size class structure of C. guianensis in these two forest types and (b) to use patterns of abundance, distribution and demographic structure to help infer key demographic stages or ecological variables that merit special focus for management. Four 400 m × 400 m plots, two in each forest type, were established to determine distribution and density patterns of C. guianensis ≥10 cm diameter at breast height (dbh) at the landscape level, and 32 10 m × 10 m subplots were randomly nested within each of the larger plots to measure individuals <10 cm dbh. Larger individuals (≥10 cm dbh) were found at higher densities in occasionally inundated forest than in terra firme forest: 25.7 trees ha⁻¹ and 14.6 trees ha⁻¹, respectively. Mean density of C. guianensis individuals <10 cm dbh was also higher in occasionally inundated forests, but variation of regeneration density among the subplots was high. Spatial distribution methods revealed a tendency toward clumping in both forest types, and both had similar size class structures, suggesting that both environments are suitable for C. guianensis. This new finding illustrates the potential for C. guianensis management in terra firme forests. High densities and clumped distributions in both forest types are also indices favorable for sustainable species management. Finally, several ecological variables (tree density and reproductive potential) were sufficiently different between terra firme and occasionally inundated forests to recommend stratification by forest type when conducting further studies on key ecological and management variables of C. guianensis.     

Species composition, similarity and diversity in three successional stages of a seasonally dry tropical forest

The objectives of this study were to describe the floristic composition, species diversity, similarity and richness among three stages of forest regeneration, and to investigate the influence of the previous land use on species composition in a seasonally dry tropical forest in northwestern Costa Rica. The species diversity and richness of woody stems with diameter greater or equal to 5 cm in 26 0.1 ha plots was found to be the greatest in the intermediate stage followed by the late and early stages. The structural changes of this chronosequence of successional stages were quantified with a modification of the Holdridge complexity index. Using satellite imagery for site selection and historical ground truth analysis the influence of past land use and the frequency of anthropogenic disturbances on species composition was illustrated.     

An empirical cohort model for management of Terra Firme forests in the Brazilian Amazon

A model to project forest growth in the Terra Firme forests of the eastern Amazon is described. It is based on 12–17 years measurements from experimental plots at Jarí and Tapajós. Forest stands are represented by cohorts of species group, diameter, and defect. There are 54 species groups, with a robust diameter increment function fitted to each, tables of mortality by crown and defect status, and recruit lists by disturbance level and locality. Stand level functions partition trees by crown status, and modify growth for stand density. Recruitment is a function of basal-area losses. Evaluation compares model performance with two experiments involving heavy felling in Tapajos State Forest. At one site, total bole volume growth of all species over 45 cm DBH was 2.56 m³ ha⁻¹ year⁻¹ over 17 years, whereas the model projected 3.13 m³ ha⁻¹ year⁻¹. At the other site, actual growth over 12 years was 0.39 m³ ha⁻¹ year⁻¹, with the model giving an identical result. Both felled and control plots are compared in the study and accurately simulated. Some weaknesses in the model are discussed.     

Forest edge quantification by line intersect sampling in aerial photographs

There is a need for accurate and efficient methods for quantification and characterisation of forest edges at the landscape level in order to understand and mitigate the effects of forest fragmentation on biodiversity. We present and evaluate a method for collecting detailed data on forest edges in aerial photographs by using line intersect sampling (LIS). A digital photogrammetric system was used to collect data from scanned colour infrared photographs in a managed boreal forest landscape. We focused on high-contrast edges between forest (height ≥ 10 m) and adjoining open habitat or young, regenerating forest (height ≤ 5 m). We evaluated the air photo interpretation with respect to accuracy in estimated edge length, edge detection, edge type classification and structural variables recorded in 20 m radius plots, using detailed field data as reference. The estimated length of forest edge in the air photo interpretation (52 ± 8.8 m ha⁻¹; mean ± standard error) was close to that in the field survey (58 ± 9.3 m ha⁻¹). The accuracy in edge type classification (type of open habitat) was high (88% correctly classified). Both tree height and canopy cover showed strong relationships with the field data in the forest, but tree height was underestimated by 2.3 m. Data collection was eight times faster and five times more cost-effective in aerial photographs than in field sampling. The study shows that line intersect sampling in aerial photographs has large potential application as a general tool for collecting detailed information on the quantity and characteristics of high-contrast edges in managed forest ecosystems.     

Formation of harvest units with genetic algorithms

Operational planning is normally based on stands as the primary unit of treatment. In recent years, interest has been directed towards the use of smaller area units such that the formation of treatment units becomes part of the operational planning. Here, the method of genetic algorithms was used in order to delineate harvesting units in a forest described as a grid of 20 m × 20 m pixels. Remote sensing data and inventory plots were employed to derive pixel estimates of forest variables. Appropriate parameter settings for the algorithm were investigated for two cases that consisted of 26 × 25 pixels. Based on the experience from these tests, the algorithm was employed in forming treatment units in an area encompassing 100 × 100 grid cells, or 400 ha. Due to the size of the problem, a two-stage procedure was suggested. The solutions of the genetic algorithm were compared with a heuristic, a cell removal algorithm, that was proposed in earlier studies of treatment unit formation. The genetic algorithm performed better than the heuristic for all the cases that were tested.     

森林二类调查中蓄积量遥感估测方法应用实例

探讨了用在ＴＭ数据中与地面对应的样点上测得的密度值和波段比，并加上定性因子与地面样地中分别测得的蓄积量进行多元回归，从而估测森林二类调查中所需的林业局、场、林班之蓄积量的方法，并与实测结果进行了对比，证明这一方法是可行的，为遥感在二类调查中的应用提供了必要依据。     

Demand for non-timber forest products: Surveys of urban consumers and sellers in Switzerland

In recent years, worldwide socioeconomic, ecological, and cultural changes have led to a paradigm shift in forestry and forest management. Some years ago, most forest enterprises exclusively focused on wood production, whereas today, forest management is expected to be multifunctional and economically as well as socially and ecologically sustainable [Harrison, S., Herbohn, J., Niskanen, A., 2002. Non-industrial, smallholder, small-scale and family forestry: what's in a name? Small-scale Forest Economics. Management and Policy 1 (1), 1–11; Schmithuesen, F., 2004. Forest policy developments in changing societies — political trends and challenges to research. Towards the sustainable use of Europe's forests: Forest ecosystems and landscape research: Joensuu: European Forest Institute, Proc., vol. 49, pp. 87–99]. In this context, non-timber forest products (NTFPs) such as forest honey, mushrooms, or berries could gain importance as an additional source of income for the forestry sector. To assess the market potential of NTFPs in Switzerland, two corresponding surveys were conducted. A consumer survey (N = 897) conducted in six cities in Switzerland investigated the purchase of Swiss NTFPs, consumer preferences, and demand potentials. An additional survey of sellers of NTFPs (N = 105) looked at these aspects from a complementary perspective. The results showed that there is a high esteem and considerable demand potential for such products among urban consumers. Food products were mentioned most frequently. Both consumers and sellers considered quality and environmental friendliness the most important attributes of NTFPs. Structural and organizational innovations and considerable marketing efforts and sales promotion would be required to expand the market for Swiss NTFP, however. Our results indicate that certification of the products' origin, environmental performance, and quality could support such efforts and that recreational and ecological forest services have a synergetic potential for the marketing of NTFPs.     

对我国森林经营问题的思考

森林经营是当前中国林业面临的一个大问题。解决这一问题的关键之一是完善和健全林业立法体系,尽快制定我国森林经营法(国有林、集体林)。     

Diversity and structure of regenerating tropical dry forests in Costa Rica: Geographic patterns and environmental drivers

Much of the dry tropical forest biome has been converted to agricultural land uses over the past several centuries. However, in conservation areas such as those in the Guanacaste and Tempisque regions of Costa Rica, tropical dry forests are regenerating due to management practices including fire suppression. To better understand the patterns of secondary succession occurring in Costa Rican tropical dry forest, we established 60 20 × 50 m plots in mature and regenerating forests in the Sector Santa Rosa (formerly known as Parque Nacional Santa Rosa) and Palo Verde National Park. Plots were stratified into three plant communities: tropical dry oak forest (Quercus oleoides) (SROAK), Santa Rosa tropical dry forest (SRTDF), and Palo Verde tropical dry forest (PVTDF). In these plots we measured and identified and all individuals >10 cm DBH, measured but did not identify stems <10 cm but taller than 1.3 m, counted woody seedlings (<1.3 m height) and analyzed soil chemical and physical properties.     

浙江省林业应对气候变化成效及措施研究

在全球气候变化大背景下,森林碳汇能力成为国际社会公认的减缓气候变暖的重要措施之一.文章总结了近年来浙江省林业应对气候变化成效:森林蓄积量从2005年的1.72亿m3提高到2019年的3.61亿m3,全省森林植被总碳储量达到2.8亿t;2006-2019年全省共完成造林更新41.2万hm2,共实施中幼林抚育面积约181....     

Tropical Forestry

An overview of the forestry sector in Costa Rica was undertaken to determine whether the existing management practices of timber resources hold the potential to meet the country's demands for timber in the immediate decades to come, and to identify changes that might be needed in the management of forested lands. To meet these goals, we examined the present status and potential future contribution of the two newest forest sectors: the management of natural forest and plantation forestry. Rcsults indicate that the present management of Costa Rica's timber resources does not hold the potential to meet the country's demands for timber for more than the next ten years without severe loss of its forests. Substantial progress is occurring, but at an insufficient rate. Moreover, despite the considerable headway made in conservation in recent years, the rate of deforestation remains high. A number of factors limit advancement in natural forest management and plantation forestry, both of which have the potential to deaccelerate deforestation. In natural forest management, constraints are the rate at which forests are being brought under management, lack of budgetary provisions for fiscal incentives to private owners who alone cannot be expected to bear the cost of benefits of natural forest management that are national or even global in their distribution, and the weak infrastructure, extension services and research support to meet management goals. In the case of plantation forestry, the capability of this sector to produce commercial timber is not known. Moreover, inadequate management and extension services together with the misuse of the incentive system by private owners is likely to limit the potential of plantations. Institutional constraints include outdated legal and bureaucratic framework, market interventions, absence of clear policy toward natural forest management and plantation forestry, poor investment in infrastructure, extension and research support, and inadequate interaction among various agencies responsible for the development of the forestry sector. Such institutional constraints have allowed the proliferation of disincentives against the development of a sustainable timber sector. If the Costa Rican government's objective is to encourage sustainable forestry, it must first clearly articulate the policy and then create the appropriate legal, economic and institutional framework for implementation of the policy. Costa Rica, with its enlightened public administration system, vast technical and scientific knowledge about its forest ecosystem and extensive assistance from international organizations, must succeed, otherwise prospects for sustainable forestry in thc less fortunate tropical countries would be bleak.     

The abundance and distribution of rattan over an elevation gradient in Sulawesi, Indonesia

The rattan flora of Central Sulawesi is abundant, species rich and patchily distributed in lowland and montane forests. I recorded the abundance and distribution of rattan on five randomly established 10 m × 1000 m transects between 830 and 1330 m elevation and associated changes in forest canopy heights, photosynthetically active radiation (PAR) and soil characteristics. Rattans were observed at all sites and elevations (100% of 10 m × 10 m sample plots in the transects contained rattan), but exhibited the greatest diversity (species richness) between 1180 and 1280 m elevation. Overall (all species and elevations), there was an average of 314 mature rattan genets per hectare. The two most prominent rattans in terms of size, abundance and distribution, Calamus zollingeri and Daemonorops robusta, averaged 62 and 40 genets/ha overall, respectively. Several other rattans, including C. leiocaulis, C. leptostachys, and C. ornatus occurred on all transects and all elevations. In contrast, C. didymocarpus, C. minahassae, C. symphysipus and Korthalsia celebica were patchily distributed, and C. didymocarpus and C. sp. (‘kalaka’) were restricted to higher elevations. Resident cane collectors differentiate C. zollingeri and D. robusta into low and high elevation forms on the basis of morphological and growth characteristics, but this distinction is not discernable in sterile specimens. Based on local classification, lowland forms of C. zollingeri and D. robusta were replaced by high elevation forms over less than 200 m vertical elevation which corresponds to the transition from upper lowland to montane forests. The mean canopy height of upper lowland forest between 900 and 1000 m was significantly greater than that of montane forests between 1100 and 1300 m (30.0 and 21.2 m, respectively). Soils in upper lowland forests had significantly higher concentrations of NO₃ and P, significantly lower organic matter levels and higher pH than montane soils in both O and A/E soil horizons. PAR levels did not vary significantly by forest type. Most large diameter rattans are marketed under a single trade name and cannot be distinguished by cane characteristics. These findings have significance for biodiversity conservation and management because rattan harvesting is widespread and unmanaged, and the Sulawesi rattan flora remains poorly known taxonomically and ecologically.     

Stand growth scenarios for Tectona grandis plantations in Costa Rica

Management scenarios with rotation lengths of 20 and 30 years were developed for different site qualities (high, medium and low) under two different management options (high individual tree growth versus high stand growth) for teak (Tectona grandis L.f.) in Costa Rica. The scenarios are based on data collected in different regions in Costa Rica, representing different site conditions, offering a variety of possible management options for high-quality teak yield.

Three competition indices were used for modeling the competition and for the definition of intensities and the plantation age at thinning. The maximum site occupation (MSO) and the Reineke density index (RDI) provide conservative stand density management limits, resulting in the need to execute several thinning frequently. The competition factor (CF) matches the field observations and seems to be more appropriate for the growth characteristics of the species.

Final stand densities varied between 120 and 447 trees ha⁻¹, with mean diameter at breast height (dbh) of 24.9–47.8 cm, and mean total heights between 23.0 and 32.4 m, depending on rotation length and site quality. The mean annual increment of total volume (MAI_Vol) at the end of the rotation varied from 11.3 to 24.9 m³ ha⁻¹ year⁻¹, accumulating a total volume over rotation of 268–524 m³ ha⁻¹.

The most suitable scenario for teak plantations for high-quality sites is the 30-year-rotation scenario with five thinnings of intensities between 20 and 50% (of the standing trees) at the ages of 4, 8, 12, 18 and 24 years. After the sectioning of the merchantable stem in 4-m length logs, the merchantable volume varied between 145 and 386 m³ ha⁻¹, with an estimated heartwood volume of 45–195 m³ ha⁻¹, both depending on rotation length and site quality.     

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。     

Burning of Amazonian forest in Ariquemes, Rondônia, Brazil: biomass, charcoal formation and burning efficiency

Biomass burning in tropical forests – the normal practice to prepare land for agriculture and ranching – has been a major source of CO₂ emitted to the atmosphere. Mass transformations by burning are still little studied in the tropics. The present study estimated parameters, such as the stock of carbon contained in the biomass, burning efficiency and the formation of charcoal and ashes in a tropical moist forest. Two sets of plots arranged in the form of ‘stars' (720 m² total) were installed in a 3.5 ha area of forest that had been felled for planting pasture at Fazenda Nova Vida, Ariquemes, Rondônia. Each ‘star' had six rays measuring 2 m × 30 m; alternating rays were designated for pre-burn and post-burn measurements. All above-ground biomass present in the plots was weighed directly before the burn in the pre-burn rays and after the burn in the post-burn rays. Pieces of wood with diameter ≥10 cm also had their biomasses estimated from volume estimates, using line-intersect sampling (LIS) in order to increase the area of sampling and to allow volume loss to be estimated as an increment based on individual pieces measured before, and after, the burn at the same point (as opposed to inferring change as a difference between independent estimates of stocks). The initial above-ground biomass (dry weight) before the burn was estimated at 306.5 ± 48.6 (mean ± SE) Mg ha⁻¹, with an additional 4.5 Mg ha⁻¹ for trees left standing. Carbon stock in the initial biomass (including trees left standing) was 141.3 (Mg C) ha⁻¹. After burning, carbon stock was reduced by 36.8% (burning efficiency). The stocks of charcoal and ash formed in the burn were, respectively, 6.4 ± 2.7 and 5.7 ± 1.0 Mg ha⁻¹. The destructive and nondestructive (LIS) methods did not differ significantly (t-test, p > 0.05) in estimating post-burn stocks of wood and charcoal. The results of this study contribute to improving the estimates of parameters needed for global carbon calculations and point to ways in which estimates of these parameters could be further improved.     

Estimating forest characteristics in scanned aerial photographs with respect to requirements for economic forest management planning

The objective of forest management planning is often expressed as maximum sustainable economic yield. Methods used to collect information for forestry planning should, therefore, include variables significant for economic evaluations of management alternatives. It is important to be able to differentiate mature stands with respect to timber volumes and species mixture. In this study, digital high‐altitude aerial photographs are tested as a data source for planning. Circular plot data from a forest estate in northern Sweden were used as reference material. Global positioning system (GPS) measurements, with differential correction, were used to georeference the plots. Harvesting priorities were calculated for each plot using the Forest Management Planning Package. Volumes, species mixture and harvest priorities were estimated using regression analysis based on textural and spectral information from aerial photographs. The results show that the dependent variables could be estimated fairly well using only spectral information, e.g., R ² = 0.44 when estimating timber volume at reference plot (10 m radius) level. Aggregated to stand level, the precision was comparable with customary field survey methods (e.g., RMSE= 13.4% for timber volume).     

嵩明县森林资源管护的难点及良化对策

嵩明县实施天保工程以来,在森林管护及生态建设上取得了一定的成绩,但在具体的森林管护工作中却存在：林农矛盾未全面解决;林火管理难度大;林内采薪、放牧、采实(菌)屡禁不止;内部管理不协调;非天保区管护松懈等问题。在分析这些难点的基础上,结合嵩明县实际,提出了相应的良化森林资源管护对策。     

浙江省集体林权制度改革分析与思考

阐述了浙江省集体林权制度改革的主要做法及取得的成效,分析了浙江集体林权制度改革中需要进一步解决的森林资源评估、林权抵押贷款、森林保险以及森林资源服务体系的建设等问题,提出了完善森林资源流转制度、推进林业投融资改革、引导创建新型的林业合作组织、完善流转交易服务体系建设等建议。     

Monitoring Victoria’s public forests: implementation of the Victorian Forest Monitoring Program

A new strategic inventory across all publicly managed forests has been installed in Victoria. For the preceding two decades, Victoria’s forest inventory has been compiled from various data sources from across the state, an approach that doesn’t allow information about the nature and rate of changes to the resource to be estimated, or for projections or forecasts to be made. To address these limitations, the Victorian Forest Monitoring Program (VFMP) was established, to monitor Victoria’s progress in meeting a commitment towards sustainable forest management, and to satisfy requirements for state and national reporting. The purpose of the new program is to ‘assess and monitor the extent, state and sustainable development of Victoria’s public forests in a timely and accurate manner.’ The VFMP consists of a plot-based system of permanent observational units located on a state-wide grid. A combination of ground-based and aerial photo plots and remotely sensed data are used to capture a set of basic attributes that are used to derive indicators of sustainability. To meet the monitoring needs a remeasurement framework has been developed to guide the change estimation procedures. The program was designed and implemented between 2009 and 2015 and used to generate data and information for the most recent Victoria’s State of the Forest Report. The first annual change estimate is due to be completed in 2017. A summary of implementation and proposed maintenance is presented and discussed in this paper.