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1.
We studied the dominant species by age category of re-growth, and how subsistence forest use through shifting cultivation impacted on the floristic composition of Baikiaea forest. For re-growth stands, variable sampling method was adopted in data collection while in mature stands, a sample plot size of 50 m 9 50 m was used at each of three study sites. Distribution of species by age categories showed that shrub, herb, and grass species were abundant in young re-growth stands while woody vegetation became common with increasing age of the re-growth stand. Hierarchical clustering for common woody species showed several species associations with age categories and also with relatively undisturbed woodland. Common regeneration mechanisms of key woody species were mainly by seed(48%), coppicing(40%) and root suckers(12%). The young re-growth stands of 6–10 and 11–15 years were characterized by B. petersiana, B.massiensis, Combretum zeyheri, and Guibourtia coleosperma. Older stands(16–20 years after abandonment) were characterized by B. plurijuga, Pterocarpus antunesii, and Baphia massiensis, thus closely mimicking the relatively undisturbed forest whose dominant key woody species were B. plurijuga, P. antunesii, and G. coloesperma. There were many stems in younger stands(2–5 years) and fewer stems in older re-growth stands of 16–20 years after abandonment following shifting cultivation. Older regrowth stands(16–20 years) were similar to undisturbed stands(P \ 0.005). The similarity between re-growth stands of 16–20 years and control stands demonstrates the recovery of Baikiaea forest over time after cessation of shifting agriculture. Baikiaea forest requires some disturbance to perpetuate the dominant species and begins to show signs of recovery from shifting cultivation within16–20 years after abandonment. This is contrary to assertions that this ecosystem could take up to about 100 years for abandoned fields to begin showing signs of  相似文献   

2.
Sustainable forest management is the process of managing forest to achieve one or more clearly specified objectives without diminishing the forest’s ability to continue providing goods and services in perpetuity. In this paper, we show how the African Timber Organization/International Tropical Timber Organization principles, criteria and indicators for the sustainable management of African forests can help timber companies assess their progress towards this goal in Gabon. Through a partnership between International Tropical Timber Organization project PD 124/01 Rev. 2(M), the World Wildlife Fund, and the ministry responsible for forests in Gabon, audits were conducted between 2012 and 2014 to evaluate the implementation of sustainable forest management in 14 forest concessions in Gabon. In general, results show that Principle 4, linked to the well-being of workers and local populations, proved the most difficult principle to implement, while Principle 3, dealing with maintaining ecological functions, was the least problematic. A number of companies were found to be experiencing significant difficulties in implementing management plans. It is also clear that independent forest certification has become a key element for ensuring the successful implementation of sustainable forest management.  相似文献   

3.
This paper includes a review of international sustainable forestry development followed by an analysis of forest policies in Bangladesh. There have been four different government forest policies in Bangladesh since 1894. The first two forest policies (1894 and 1955) were exploitative in nature. Most of the regulatory documents were developed during the first two policy periods. The third forest policy instituted in 1979 by the sovereign Bangladesh government had contradictory elements and mutually inconsistent policy statements. It addressed for the first time forestry extension through mass motivation campaign. Current forest policy formulated in 1994 has been considered to be the most elaborate policy in the history of the country. Under this policy, participatory social forestry has been institutionalized in Bangladesh. The analysis shows that, although it is possible to attain the stated policy targets, progress is slow and is blocked on several fronts. A number of identified technical, managerial and logistical problems are hindering policy and program implementation. In addition, corruption contributes to the observed problems. The real strength of Bangladesh forestry is locally based, participatory forestry, co-management of protected areas and highly motivated people who increasingly recognize the need for a healthy forest ecosystem that will provide future economic stability. Because it is the rich homestead forests of Bangladesh that generate the majority of commercial forestry products, it is important that education continues at the grass-roots level. In addition, educated forestry and environment professionals have been identified as the future driving forces towards better, and sustainable, forest management. Results of this study make it clear that Bangladesh and other developing countries are not presently in a position to accept and adopt internationally derived forest policies due to inadequate institutional support, political instability and poor governance. Therefore, along with development of criteria and indicators of sustainable forest management and forest certification, international policy scientists must consider institutional development, professional skill development, identification and adoption of indigenous technology and long-term financial support in developing countries. Without these, all international processes, policies and directives will be of little value and produce few substantive results.  相似文献   

4.
Current knowledge of the within-site variability of major stand structural features in beech dominated natural forests is limited. Numerous studies have used just several small plots for characterizations of natural stands, but this may lead to generalizations based on unreliable results. This study shows how major stand structural features vary at the local scale, and how suitable sampling may reflect this variability. Stem position maps of three natural forests in the Czech Republic (Zofin 71 ha, Salajka 19 ha and Zakova hora 17 ha) were used. Each vector stem position map representing all live and dead trees with DBH ≥ 10 cm was intensively analyzed using square sample plots of different sizes (10 × 10 m; 20 × 20 m; 30 × 30 m; 50 × 50 m; 100 × 100 m; 140 × 140 m and 200 × 200 m). Basic statistics (mean, standard deviation, coefficient of variation, min., and max.) were calculated for every plot size and each of six major stand features: density, basal area and volume of living trees, volume of course woody debris, total volume and proportion of course woody debris in total volume.  相似文献   

5.
The contiguous forest landscapes of the Brigalow Belt Bioregion in Australia's subtropics, known as ‘the western hardwood forests’ are thought to be important for biodiversity conservation through the provision of continuous habitat features in an otherwise extensively cleared region. However, these forests have a long management history, as they are also important for timber production and stock grazing. Knowledge of the effect of these and other disturbances on the distribution and abundance of key structural or habitat features are limited and forest management activities thus continue uninformed. To address this knowledge gap, we investigated the effects of prescribed and non-prescribed disturbances on the distribution and abundance of six key habitat features (live and dead trees with hollows, large mature live trees, shrub abundance, downed coarse woody debris and litter cover) at 120 sites located in spotted gum Corymbia citriodora dominant forests within the western hardwoods.  相似文献   

6.
不同密度油松飞播林灌草多样性与林分空间结构关系   总被引:1,自引:0,他引:1  
林下植被是森林生态系统的重要组成部分,物种多样性和林分空间结构是评估森林生态系统功能和林分经营质量的关键指标。本文以44年生油松飞播林为研究对象,通过典型样地调查,运用单因素方差分析和相关分析,分析林分密度对油松飞播林灌草多样性和林分空间结构的影响。结果表明:(1)林分密度对灌草多样性指数影响差异显著,灌草多样性指数均在低密度的样地中达到最大值。(2)混交度和密集度受林分密度影响显著,而林分密度对乔木胸径和树高的影响体现在林分水平上,而非空间结构单元中。(3)林分空间结构与灌草多样性之间有密切联系,影响林下植被多样性的最主要因子是乔木层混交度。因此,未来在飞播林经营活动中,调整林分密度的同时,应综合考虑林木分布格局,兼顾灌草多样性保护。  相似文献   

7.
The Afromontane forests of Ethiopia have been under a serious degradation threat. Assessment of floristic diversity and species composition in Biteyu forest of Gurage mountain chain in the central Ethiopia was conducted to examine the pattern of forest structure. Thirty plots of 30 m×30 m were used to record the vegetation and environmental data using systematic sampling technique. The local name, plant scientific names, DBH, height,species abundance and percentage canopy cover of plant species were recorded. Shannon diversity index and Sorensen's coefficients was used for comparison among communities and similar forests in the country. Threats to the forest biodiversity in Biteyu were determined by counting cattle interference and wood stumps as disturbance indicators. Relative Euclidean Distance measures by using Ward's method(linkage) was applied for cluster analysis. Environmental variables were also recorded in each plot. Woody species population structure, basal area and importance value index were analyzed using spreadsheet programs. Data on species distribution and environmental variables in the forest were analyzed by canonical correspondence analysis. A total of 190 species in 154 genera under 73 families were identified. Twenty species were found to be endemic taxa to the Flora Area. Only three plant community types were identified from the cluster analysis due to the high human influence. The Sorensen's coefficient showed the resemblance of the Biteyu forest with other Dry Evergreen Afromontane forests in the country. Moreover, altitude and slope strongly affect the species composition and structure of Biteyu forest. Given the high anthropogenic influence, high endemism, high dependence of the local community on the forest resources, forest conservation and restoration measures should be done by stakeholders.  相似文献   

8.
Sustainable Forest Management (SFM) is an integral component of sustainable development. Iran is a Near East country with low forest cover. Iran uses 7 criteria and 65 indicators for regional and national monitoring of forest management. We evaluated the status of SFM in Iran, and a location imaging in its path towards SFM was provided by existing validation data and library references for the Criteria and Indicators (C&I) adopted in the Near East, We identify challenges and opportunities associated with SFM in Iran. Although the information to evaluate the trend of SFM in Iran was incomplete, we compiled some information on the basis of C&I. Comparison of some indicators with the values for the rest of the world revealed that the situation in Iran is very different. Although some indicators revealed a better situation in Iran, Iran lags the rest of the world in the implementation of SFM. Iran, like many countries, is trying hard to find ways to sustainably use its forests. Not all C&I for assessment of SFM in Iran have been determined or defined. However, a consistent and comprehensive framework of criteria and indicators to monitor progress towards SFM is being applied. Defining some C&I is still at an early stage.  相似文献   

9.
Soil organic matter (SOM) has been adopted as an indicator of soil fertility based on the rationale that SOM contributes significantly to soil physical, chemical, and biological properties that affect vital ecosystem processes of forests in Australia. A study was undertaken to evaluate the utility of SOM as an indicator of SFM at two long-term experimental sites in native eucalypt forests, including Silvertop Ash (E. sieberi L. Johnson) and Mountain Ash (E. regnans F. Muell.) in Victoria. This study examines the relative contributions made by various sources of carbon in soil profiles (0–30 cm) of forest soils, viz. mineral soil (<2 mm), plant residues, charcoal (>2 mm), and rock fragments (>2 mm). The long-term changes in these fractions in response to management-induced soil physical disturbance and fire (unburnt, moderate and high intensity) were evaluated. After 10 years, carbon levels in the fine soil fraction (soil <2 mm including fine charcoal) were similar across the range of fire disturbance classes in Mountain Ash forest (20–25 kg/m2) and Silvertop Ash forest (7–8 kg/m2). Likewise differences in carbon associated with other fractions, viz. microbial biomass, labile carbon, plant residues and rock fragments were comparatively small and could not be attributed to fire disturbance. Burning increased the charcoal carbon fraction from 5 to 23 kg/m2 in Mountain Ash forest and from 1 to 3 kg/m2 in Silvertop Ash forest. Taking into account, the percentage area affected by fire, increases in total soil carbon in these forests were estimated at 25 and 7 t/ha, respectively.

The effects of physical disturbance of soils were examined at one site in Mountain Ash forest where soil cultivation was used as site preparation rather than the standard practice of burning of logging residues. Total carbon in soil profiles decreased from 29 to 21 kg/m2 where soil disturbance was severe, i.e. topsoil removed and subsoil disturbed. This was mainly due to a decrease in charcoal carbon from 6.8 to 1.7 kg/m2 but severe soil disturbance also increased the amount of carbon associated with rock fragments from 1.6 to 3.5 kg/m2.

Management-induced fire increased the coarse charcoal content of soil profiles substantially, thus increasing total carbon content as well as the proportion of recalcitrant carbon in SOM. In contrast, there was little change in the carbon content of the fine soil fraction including the labile and biologically active fractions indicating that these SOM fractions most relevant to ecosystem processes showed little long-term impact from soil disturbance and fire. Conventional sampling of the fine soil fraction (<2 mm) only represented between 50% and 70% of total carbon in the soil profiles. In contrast, total nitrogen in this fraction represented between 75% and 90% of the nitrogen in soil profiles and was less affected by changes in the contributions of N made by coarse fractions. Monitoring of soil N rather than C as an indicator of soil fertility and SFM may be more appropriate for forest soils with significant charcoal content.  相似文献   


10.
The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer and Peripheral Zone were 155.5 trees·hm^-2, 795.4 trees·hm^-2 and 3.9 m^2·hm^-2, 5.8 m^2·hm^-2, respectively. No regeneration and natural trees were found in Peripheral Zone and the Zone is totally occupied by exotic species where the Buffer Zone comprised of both natural and exotic trees. The Peripheral Zone belonged to younger and smaller trees whereas the Buffer Zone belonged to mixture of smaller, taller, younger and mature trees simultaneously. For the practicing of different agroforestry systems both Zones have lost their original characters of Sal forest.  相似文献   

11.
ABSTRACT

This article establishes principles conveyed by criteria and indicators as a useful tool for measuring progress made toward sustainable forest management (SFM). Pedagogically, the conceptual construction raises questions on the following topics: (a) the various management practices and policies that exist in the high forest zone, (b) how criteria and indicators for assessments are selected, and (c) how progress made toward SFM is measured. Performance scores are established for indicators identified within the three sectors (forest ecosystems, forest communities, and the economy) for sustainability assessment. Measuring progress toward SFM operations are quantitatively performed with estimated maximum and minimum thresholds levels at which resource-use would be sustained using the Measure of Forest Resource-Use Sustainability Scale (MoFRUSS). The outcome of the measurement operations, as depicted by MoFRUSS, reveals the actual extent to which stakeholder’s initiatives toward sustainable forest management has progressed and in which direction it is moving. It also offers optional policy baskets for resource management interventions from which the socio-eco economic bundle is recommended if the forestry sector of Ghana’s Vision 2020 (sustainable development) is to be achieved with improved societal well-being, improved environmental health and vitality, and improved economic growth and development.  相似文献   

12.
Forest management in Romania is based on sustained yield. However, the current sustained-yield policy may be outdated and may not be the best way of achieving Romania's intended objectives of biological sustainability and community stability. The existing policy also does not incorporate objectives consistent with Romania's new economic and social systems. We examine the potential economic net benefits from timber harvests that could result from changes to the existing sustained-yield policy by comparing the state-approved management plan of a community forest with three alternative forest management plans. We find that the three alternatives appreciably increase the potential economic net benefits. Certain aspects of these alternative plans deviate from Romania's current sustained-yield criteria; however, the costs associated with changes to the current regime could be balanced by the economic net benefits of implementing an alternative management plan. To employ the same static forest management policy throughout time without adapting to a dynamic socio-economic environment will likely lead to inefficient, ineffective, and unproductive utilization of Romania's forest resources.  相似文献   

13.
Forest soil organic carbon (SOC) and forest floor carbon (FFC) stocks are highly variable. The sampling effort required to assess SOC and FFC stocks is therefore large, resulting in limited sampling and poor estimates of the size, spatial distribution, and changes in SOC and FFC stocks in many countries. Forest SOC and FFC stocks are influenced by tree species. Therefore, quantification of the effect of tree species on carbon stocks combined with spatial information on tree species distribution could improve insight into the spatial distribution of forest carbon stocks.We present a study on the effect of tree species on FFC and SOC stock for a forest in the Netherlands and evaluate how this information could be used for inventory improvement. We assessed FFC and SOC stocks in stands of beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii), Scots pine (Pinus sylvestris), oak (Quercus robur) and larch (Larix kaempferi).FFC and SOC stocks differed between a number of species. FFC stocks varied between 11.1 Mg C ha−1 (beech) and 29.6 Mg C ha−1 (larch). SOC stocks varied between 53.3 Mg C ha−1 (beech) and 97.1 Mg C ha−1 (larch). At managed locations, carbon stocks were lower than at unmanaged locations. The Dutch carbon inventory currently overestimates FFC stocks. Differences in carbon stocks between conifer and broadleaf forests were significant enough to consider them relevant for the Dutch system for carbon inventory.  相似文献   

14.
Selection of appropriate aquatic habitat indicators is important for supporting sustainable forest and watershed management. To date, many identified watershed indicators have not been well tested. To address this issue, we sampled 28 stream reaches in the central and south interior of British Columbia, Canada. The selected reaches were similar with respect to gradient, watershed and topographic characteristics but with various levels of forest harvesting. Aquatic habitat indicators were derived based on a field survey, involving substrates, channel dimensions, pools, and large woody debris (LWD), together with some ratios and derivatives generated from them. Timber harvest disturbance at the watershed scale was quantified by calculating historical forest clear-cut area based on the BC vegetation resources inventory database. To account for the subsequent forest recovery, equivalent clear-cut area (ECA) was calculated based on the dominant species of each stream watershed and its regrowth since being logged. Pearson correlation coefficients showed that percent ECA and percent historical clear-cut area could effectively quantify the cumulative logging disturbance by limiting the effect of factors not related to logging activity (i.e., watershed area and elevations). These two variables were then related to the aquatic habitat indicators. Pearson correlation analyses found that relative width (ratio of D to bankfull width) (D is the b axis diameter of the largest substrate particle found in the reach), relative roughness (ratio of D to bankfull depth), pool frequency and per piece LWD volume are sensitive to percent ECA, i.e., significant (p < 0.01) while independent of influence from non-forest logging activity related factors and spatial clustering of samples. This relationship also holds true for the last two indicators when related to percent historical clear-cut area, though with a reduced degree of correlation. In addition, mean LWD diameter also showed significant relationship with percent historical clear-cut area, but not with percent ECA. Overall, per piece LWD volume was considered as the best aquatic habitat indicator. The performance of mean LWD diameter was comparable to per piece LWD volume if percent historical clear-cut area was used to quantify forest disturbance. Implications of these findings for forest management strategies are discussed.  相似文献   

15.
The paper uses cause mapping and structural analysis to analyse how key consensus-building criteria influence the development of cooperation among and between stakeholders and a government agency. The analyses are based on a comparative study of two Local Citizens Committees (LCCs) in Ontario, Canada. Given–Means–Ends (GME) analysis is used to identify the informal goals of LCCs, including the development of cooperation, and LCCs' influence over consensus-building criteria, and Context, Structure and Performance (CSP) analysis is used to identify the relative influence of key consensus-building criteria on cooperation criteria. The paper concludes with a discussion of the relationship between the structural analysis and content analysis of the same data and four inferences for consensus-building and co-management theories.  相似文献   

16.
Avalanche disturbances are important processes in many subalpine forest ecosystems but have received relatively little research attention in comparison to other major types of disturbances. This paper presents a review of interactions between forests and snow avalanches in mountain ecosystems and discusses how avalanche disturbance regimes and associated management may change in the future. Avalanche disturbance regimes are two-way interactions in which forest structure and composition affect avalanches and avalanches, in turn, affect structure and composition.  相似文献   

17.
Silvicultural practices that provide a wide variety of vegetative composition and structure (habitats) in young stands should help manage for biological diversity across forested landscapes. This study was designed to test the hypotheses that: (i) abundance and diversity of stand structure attributes (species diversity and structural diversity of herb, shrub and tree layers) and forest floor small mammal communities, and (ii) relative habitat use by large herbivores, will increase from unthinned to conventionally thinned to chemically thinned stands of young lodgepole pine (Pinus contorta) forest. Replicate study areas were located near Summerland, Kelowna and Williams Lake in south-central British Columbia, Canada. Each study area had three treatments: a conventionally thinned, a chemically thinned and an unthinned stand. Pre-commercial thinning was conducted in 1993. Coniferous stand structure and understory vegetation were measured prior to thinning in 1993 and 5 years later in 1998. Small mammal populations were sampled intensively from 1993 to 1998. Relative habitat use by large herbivores was sampled in 1998.

Our results indicate that chemical thinning of young lodgepole pine stands produced an aggregated pattern of crop trees compared with stands subjected to conventional thinning. Diameter growth of crop trees in the chemically thinned stands was similar to that in the conventionally thinned, but also to that in unthinned stands. Although horizontal stratification (aggregates of trees) was enhanced, vertical stratification (structural diversity of vegetation) was less in the chemically than conventionally thinned stands. Abundance and diversity of understory vegetation and small mammal communities were generally unaffected by stand thinning in these particular installations. Relative habitat use by mule deer (Odocoileus hemionus) occurred in a gradient from highest in the conventionally thinned stand to lowest in the unthinned stand. Habitat use by snowshoe hares (Lepus americanus) tended to have the opposite trend. Moose (Alces alces) exhibited no difference in habitat use among stands. Thus, although there were few differences among treatment stands, chemical thinning could be used to develop an aggregated pattern of crop trees in pre-commercially thinned stands to maintain habitat for herbivores such as snowshoe hares and mule deer. Understory plant and forest floor small mammal communities would be maintained in these stands as well.  相似文献   


18.
The importance of structural complexity in forest ecosystems for ecosystem diversity has been widely acknowledged. Tree microhabitat structures as indicators of biodiversity, however, have only seldom been the focus of diversity research although their occurrence is highly correlated with the abundance of forest species and ecosystem functions. In this study, microhabitat structures in Douglas-fir (Pseudotsuga menziesii) forests were defined and their frequency and abundance in natural stands and stands of varying active management histories and stand ages was compared. Indicator microhabitat structures for natural forests were determined and the relationship of the abundance of microhabitat structures with tree diameter of Douglas-fir trees was analysed.  相似文献   

19.
This study determined existing quantitative stand structure and its implication on silvicultural management of homestead forestry. The results showed that fruit and timber species have importance values of 57% and 43%, respectively, in the study area, which is in contrast to the commonly held view of absolute domination of fruit species. The fruit species were only moderately dominant over timber species in relation to the quantitative stand structure of homestead forests. Two fruit species, Mangifera indica and Artocarpus heterophyllus, contribute about one third of the stand structure, while amongst the timber species Samanea saman and Albizia spp. are the most important species. A simulated evaluation of soil expectation value of homestead forest showed that the existing stand structure would not maximize the financial gain perpetually, in contrast, the quantitative stand structure could be effectively regulated to maximize grower benefit without compromising the existing biodiversity. Optimization of the quantitative stand structure of homestead forests could be achieved by changing the species composition, specifically by increasing the percentage of commercially valuable species like Michelia champaca, Tectona grandis, Artocarpus chapalasha, Gmelina arborea, Litchi chinensis, Citrus grandis, Psidium guajava, Lagerstroemia speciosa, Swietenia mahogany, etc., reducing the percentage of species like Mangifera indica, Artocarpus heterophyllus, Cocos nucifera, Samanea saman, Spondias pinnata, Phoenix sylvestris, etc., and eradicating species like Lannea coromandelica and Ficus benghalensis. It was estimated that the optimal relative density of fruit and timber species that would generate optimal financial benefit would be 40.4% and 59.6%, respectively.  相似文献   

20.
A proper forest planning process includes the assessment of the decision-makers’ preferences concerning the future forest use. For some owners, it may be a difficult task to express their preferences exactly and in the form that is required for planning calculations. This study presents a new kind of approach for analyzing the effects of preferential uncertainty. The approach consists of examination of the differences in the actual decision variables in forest planning, i.e. selected treatments for stands between holding-level forest plans. In example calculations, the preferential uncertainty was examined from three different viewpoints: the uncertainty in the weights of the objective variables; the uncertainty in the partial utility function; and the combination of these two uncertainty sources. One thousand preference realizations were generated for each of these uncertainty sources. More than one treatment schedules are proposed for stands that are affected by preferential uncertainty. These stands were detected from among the resulting set of 1,000 forest plans. With this done, two potential decision-making strategies, an adaptive behavior strategy and a threshold proportion strategy, were applied as guides in decision-making for stands, which have more than one treatment alternative selected in the produced optimal forest plans. The adaptive behavior technique required that the forest owner select one treatment alternative for at least one stand that has more than one proposed treatment alternative. The treatment alternatives having frequencies exceeding the given threshold frequency were all accepted simultaneously in the threshold strategy. The main benefit of the approach is to present the effects of uncertainties in a way that can be easily understood by the actual decision-makers. It is a promising tool for practical decision-making situations because at least Finnish non-industrial private forest owners quite often focus on making stand-level forest management decisions. It is also suitable for examinations of other uncertainty sources such as timber prices or inventory data.  相似文献   

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