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181.
This study analyzes the fishing areas or spots used by artisanal fishers of the Atlantic Forest coast. Fishers include inhabitants of islands of the SE Atlantic Forest in Brazil. Data on fish landings were collected for different islands, in 1986 and 1989–1990, for species caught, technology used and fishing time. Fishing spots were marked or rechecked using GPS in 1997–1999. Fishing is performed in paddled, motorized canoes or in small boats with set gillnets or hook and line. Marine animals caught vary from place to place and include fish, shrimp, squid and crab. Spots used are very stable in time, since they did not change for about 10 years. Among other factors, technology limits the range of access of the fishers to the spots. An informal division of fishing areas or spots is observed, based on the locality of residence of the fishers. The mapping and observed division of fishing spots may be used in local management, helping to control the intrusion of industrial fishers in artisanal areas. Local rules and discrimination of spot users may be helpful for artisanal fishers, especially in areas where conflicts with trawlers occur. The observed long-term stability of the use of fishing spots by artisanal fishers and conflicts with other users indicate the urgency of considering local rules for conservation purposes in Atlantic Forest coastal areas. Electronic Publication  相似文献   
182.
森林特殊火行为格局的卫星遥感研究   总被引:13,自引:4,他引:9  
舒立福  寇晓军 《火灾科学》2001,10(3):140-143
由于多变的天气条件,复杂的地形和植被分布,引起火行为格局的变化,借助GIS和卫星遥感技术,以1987年大兴安岭5.6大火为对策,进行火行为变化规律和火行为的时空格局研究,环境风对火行为具有决定性作用,大风期间火强度极高,过火区为火蔓延的廓道,较大的山脉对林火有阻隔作用,森林采伐改变可燃物连续性,可以改变火行为,人类扑火对大火作用不明显,小地形可产生不同火烧强度的细微结构。  相似文献   
183.
A stand-scale forest model has been developed that dynamically simulates, besides carbon (C) and water (H2O) fluxes, wood tissue development from physiological principles. The forest stand is described as consisting of trees of different size cohorts (for example, dominant, co-dominant and suppressed trees), either of the same or of different species (deciduous or coniferous). Half-hourly C and H2O fluxes are modeled at the leaf, tree and stand level. In addition to total growth and yield, the model simulates the daily evolution of tracheid or vessel biomass and radius, parenchyma and branch development. From these data early and latewood biomass, wood tissue composition and density are calculated. Simulation of the labile C stored in the living tissues allows for simulation of trans-seasonal and trans-yearly effects, and improved simulations of long-term effects of environmental stresses on growth. A sensitivity analysis was performed to indicate the main parameters influencing simulated stem growth and wood quality at the tree and stand level. Case studies were performed for a temperate pine forest to illustrate the main model functioning and, more in particular, the simulation of the wood quality. The results indicate that the ANAFORE model is a useful tool for simultaneous analyses of wood quality development and forest ecosystem functioning.  相似文献   
184.
Recent ecosystem and fire management research aims to quantify, model and understand historical fire disturbances focusing on their frequency, size and distribution. Less attention, however, has been paid to fire boundaries and their location on the landscape. Our study presents a spatial method to quantify the location, pattern and persistence of historical fire boundaries using tree ring fire scar data in the lower Stein watershed (British Columbia). Data from Pinus ponderosa and Pseudotsuga menziesii collected in 35 one-hectare plots over a 412-hectare study area were analyzed for the period between 1879 and 1947 using local spatial statistics and boundary detection techniques. Results of the analysis using local spatial statistic Moran’s I showed significant clustering of boundaries near topographic breaks. To determine and test whether fire boundaries between plots were persistent, we used boundary detection methods and developed a spatially restricted randomization test. The results revealed that out of 86 possible boundary links, 8 were significantly persistent (P < 0.025) while another 8 were significantly rare (P < 0.025). These spatial methods can help determine the historical spatial configuration of persistent boundaries and can be used to maintain natural forest dynamics.
Geraldine J. JordanEmail:
  相似文献   
185.
ABSTRACT

This study was carried out on the accumulation and occurrence of Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Rb, Sr and Zn in the mushroom Amanita muscaria and forest topsoil from two lowland sites in the Tuchola Pinewoods in the north-central region and an upland site in the ?wietokrzyskie Mountains in the south-central region of Poland. Topsoil from the upland location showed Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, Na and Zn at significantly higher concentration levels (pseudo-total fraction and often also the labile or extractable fraction) than at both lowland locations, where topsoil was richer in Mg, and similar in Rb. Amanita muscaria from the upland region differed from individuals collected in the lowland sites by higher concentration levels of Cd, Cu, Hg and Mn in caps. This could be related to higher concentration levels of the metallic elements in topsoil in the upland region. On other side, A. muscaria from the upland site was poorer in Co and Fe in caps, and in Ca, Co, Fe and Sr in stipes. In spite of the differences in content of the geogenic metallic elements in topsoil between the lowland and upland locations, A. muscaria from both regions was able to regulate uptake and accumulation of Ag, Al, Ba, Ca, K, Mg, Na, Rb and Zn, which were at similar concentration levels in caps but not necessarily in stipes.  相似文献   
186.
The natural range of variation of ecosystems provides reference conditions for sustainable management and biodiversity conservation. We review how the understanding of natural reference conditions of boreal forests in northern Europe has changed from earlier perceptions of even-aged dynamics driven by stand-replacing disturbances towards current understanding highlighting the role of non-stand-replacing disturbances and the resultant complex forest dynamics and structures. We show how earlier views and conceptual models of forest disturbance dynamics, including the influential ASIO model, provide estimates of reference conditions that are outside the natural range of variation. Based on a research synthesis, we present a revised forest reference model incorporating the observed complexity of ecosystem dynamics and the prevalence of old forests. Finally, we outline a management model and demonstrate its use in forest ecosystem management and show how regional conservation area needs can be estimated. We conclude that attaining favourable conservation status in northern Europe’s boreal forests requires increasing emphasis on ecosystem management and conservation for old forest characteristics.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01444-3) contains supplementary material, which is available to authorized users.  相似文献   
187.
热振森林大型土壤动物群落特征及其影响因素   总被引:1,自引:0,他引:1  
为了解西藏拉萨市林周县热振国家森林公园不同海拔大型土壤动物群落的空间分布特征及其与环境因子的关系,于2021年7月(夏季)根据其地理特征设置了三个不同海拔共9个样地.采用手捡法对大型土壤动物进行收集,并将其保存在75%酒精的收集管中,同时测定相应的环境因子.共捕获大型土壤动物1427个,经形态学鉴定隶属于2门5纲15目21科,其中优势类群为姬马陆科(Julidae)和蚁科(Formicidae),占总捕获量的66.0%.常见类群共10类,占总捕获量的31.3%;稀有类群占总捕获量的2.7%.热振国家森林公园大型土壤动物的类群、Shannon多样性指数、均匀度指数和优势度指数在三个不同海拔之间无显著性差异(P>0.05).大型土壤动物群落Jaccard相似性系数位于0.15~0.77.Pearson相关性结果显示,大型土壤动物个体数与海拔呈极显著负相关(P<0.01),与土壤温度和pH呈显著正相关(P<0.05);冗余分析显示,排序轴1和轴2共同解释了的类群组成变化的55.0%,全磷(TP)和有效磷(AP)为显著性解释变量,对大型土壤动物群落的解释率分别为29.6%和18.5%,是影响大型土壤动物群落的主要环境因子.  相似文献   
188.
Interviews with Chinese forest products manufacturers were conducted to explore their attitudes towards forest certification and related issues. Participants comprised owners, CEOs, and managers in 20 Chinese wood products companies, including producers of furniture, doors, flooring, and various engineered wood products. The interviews were used to analyze the extent to which participants were considering adopting forest certification and what might motivate such a decision. This was done by assessing their awareness and knowledge of certification. The results indicated that participants' understanding of forest certification was extremely low, despite major efforts in China to raise awareness of the issue. Potential economic benefits were the most frequently cited reason to adopt certification, including gaining or maintaining competitive advantage over their industry counterparts, improved access to both domestic and export markets, better customer recognition, and enhanced corporate responsibility practices. Some interviewees (3 out of 20) considered that certification would become a mandatory requirement or industry standard, and that this would be the only viable motivation for certification given that the financial benefits were potentially limited. According to the participants, the main differences between certified and uncertified wood products operations related to improved market access and public image. Interviewees felt that cooperation between and support from governments and the forest industry would enable the enhanced awareness of certification amongst manufacturers and the general public. This, in turn, could serve to stimulate demand for certified products.  相似文献   
189.
This study examines the value of fallow ecosystem services in shifting cultivation, including hydrological externalities that may affect other farms. Using farm-level survey data from the Brazilian Amazon, I estimate a production function to assess the value of forest fallow and test whether it provides local externalities to agricultural production. Soil quality controls, instrumental variables, and spatial econometric approaches help address endogeneity issues. I use GIS data on external forest cover at the farm level and model the hydrological externality as an upstream-to-downstream process. The estimated parameters indicate that fallow contributes significantly to productivity both on farm and downstream. In addition, most farms allocate sufficient land to fallow, accounting for both the value of hydrological spillovers and the opportunity cost of land left out of cultivation. These results suggest that farming communities may have some self-interest in preserving forest cover locally—a finding that may bolster policy efforts aimed at conserving tropical forests for their global public goods.  相似文献   
190.
When the development of gap models began about three decades ago, they became a new category of forest productivity models. Compared with traditional growth and yield models, which aim at deriving empirical relationships that best fit data, gap models use semi-theoretical relationships to simulate biotic and abiotic processes in forest stands, including the effects of photosynthetic active radiation interception, site fertility, temperature and soil moisture on tree growth and seedling establishment. While growth and yield models are appropriate to predict short-term stemwood production, gap models may be used to predict the natural course of species replacement for several generations. Because of the poor availability of historical data and knowledge on species-specific allometric relationships, species replacement and death rate, it has seldom been possible to develop and evaluate the most representative algorithms to predict growth and mortality with a high degree of accuracy. For this reason, the developers of gap models focused more on developing simulation tools to improve the understanding of forest succession than predicting growth and yield accurately.In a previous study, the predictions of simulations in two southeastern Canadian mixed ecosystem types using the ZELIG gap model were compared with long-term historical data. This exercise highlighted model components that needed modifications to improve the predictive capacity of ZELIG. The updated version of the model, ZELIG-CFS, includes modifications in the modelling of crown interaction effects, survival rate and regeneration. Different algorithms representing crown interactive effects between crowns were evaluated and species-specific model components that compute individual-tree mortality probability rate were derived. The results of the simulations were compared using long-term remeasurement data obtained from sample plots located in La Mauricie National Park of Canada in Quebec. In the present study, three forest types were studied: (1) red spruce-balsam fir-yellow birch, (2) yellow birch-sugar maple-balsam fir, and (3) red spruce-balsam fir-white birch mixed ecosystems. Among the seven algorithms that represented individual crown interactions, two better predicted the changes in basal area and individual-tree growth: (1) the mean available light growing factor (ALGF), which is computed from the proportion of light intercepted at different levels of individual crowns adjusted by the species-specific shade tolerance index, and (2) the ratio of mean ALGF to crown width. The long-term predicted patterns of change in basal area were consistent with the life history of the different species.  相似文献   
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