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141.
142.
Measurements and simulation of forest leaf area index and net primary productivity in Northern China
Large scale process-based modeling is a useful approach to estimate distributions of global net primary productivity (NPP). In this paper, in order to validate an existing NPP model with observed data at site level, field experiments were conducted at three sites in northern China. One site is located in Qilian Mountain in Gansu Province, and the other two sites are in Changbaishan Natural Reserve and Dunhua County in Jilin Province. Detailed field experiments are discussed and field data are used to validate the simulated NPP. Remotely sensed images including Landsat Enhanced Thematic Mapper plus (ETM+, 30 m spatial resolution in visible and near infrared bands) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER, 15m spatial resolution in visible and near infrared bands) are used to derive maps of land cover, leaf area index, and biomass. Based on these maps, field measured data, soil texture and daily meteorological data, NPP of these sites are simulated for year 2001 with the boreal ecosystem productivity simulator (BEPS). The NPP in these sites ranges from 80 to 800 gCm(-2)a(-1). The observed NPP agrees well with the modeled NPP. This study suggests that BEPS can be used to estimate NPP in northern China if remotely sensed images of high spatial resolution are available. 相似文献
143.
Despite increasing attention to management of headwater streams as sources of water, sediment, and wood to downstream rivers,
the extent of headwater channels and perennial flow remain poorly known and inaccurately depicted on topographic maps and
in digital hydrographic data. This study reports field mapping of channel head and perennial flow initiation locations in
forested landscapes underlain by sandstone and basalt lithologies in Washington State, USA. Contributing source areas were
delineated for each feature using a digital elevation model (DEM) as well as a Global Positioning System device in the field.
Systematic source area–slope relationships described in other landscapes were not evident for channel heads in either lithology.
In addition, substantial variability in DEM-derived source area sizes relative to field-delineated source areas indicates
that in this area, identification of an area–slope relationship, should one even exist, would be difficult. However, channel
heads and stream heads, here defined as the start of perennial flow, appear to be co-located within both of the lithologies,
which together with lateral expansion and contraction of surface water around channel heads on a seasonal cycle in the basalt
lithology, suggest a controlling influence of bedrock springs for that location. While management strategies for determining
locations of channel heads and perennial flow initiation in comparable areas could assign standard source area sizes based
on limited field data collection within that landscape, field-mapped source areas that support perennial flow are much smaller
than recognized by current Washington State regulations. 相似文献
144.
A decision support system for managing forest fire casualties 总被引:3,自引:0,他引:3
Bonazountas M Kallidromitou D Kassomenos P Passas N 《Journal of environmental management》2007,84(4):412-418
145.
Despite increasing interest in learning from Indigenous communities, efforts to involve Indigenous knowledge in environmental policy-making are often fraught with contestations over knowledge, values, and interests. Using the co-production of knowledge and social order (Jasanoff, 2004), this case study seeks to understand how some Indigenous communities are engaging in science-policy negotiations by linking traditional ecological knowledge (TEK), western science, and other knowledge systems. The analysis follows twenty years of Indigenous forest management negotiations between the Xáxli’p community and the Ministry of Forests in British Columbia (B.C.), Canada, which resulted in the Xáxli’p Community Forest (XCF). The XCF is an eco-cultural restoration initiative that established an exclusive forest tenure for Xáxli’p over the majority of their aboriginal territory—a political shift that was co-produced with new articulations of Xáxli’p knowledge. This research seeks to understand knowledge co-production with Indigenous communities, and suggests that existing knowledge integration concepts are insufficient to address ongoing challenges with power asymmetries and Indigenous knowledge. Rather, this work proposes interpreting XCF knowledge production strategies through the framework of “Indigenous articulations,” where Indigenous peoples self-determine representations of their identities and interests in a contemporary socio-political context. This work has broader implications for considering how Indigenous knowledge is shaping science-policy negotiations, and vice versa. 相似文献
146.
Ted S. Vinson Tatyana P. Kolchugina Kenneth A. Andrasko 《Environmental management》1996,20(Z1):S111-S118
Greenhouse gas (GHG) mitigation options in the Russian forest sector include: afforestation and reforestation of unforested/degraded land area; enhanced forest productivity; incorporation of nondestructive methods of wood harvesting in the forest industry; establishment of land protective forest stands; increase in stand age of final harvest in the European part of Russia; increased fire control; increased disease and pest control; and preservation of old growth forests in the Russian Far-East, which are presently threatened. Considering the implementation of all of the options presented, the GHG mitigation potential within the forest and agroforestry sectors of Russia is approximately 0.6–0.7 Pg C/yr or one half of the industrial carbon emissions of the United States. The difference between the GHG mitigation potential and the actual level of GHGs mitigated in the Russian forest sector will depend to a great degree on external financing that may be available. One possibility for external financing is through joint implementation (JI). However, under the JI process, each project will be evaluated by considering a number of criteria including also the difference between the carbon emissions or sequestration for the baseline (or reference) and the project case, the permanence of the project, and leakage. Consequently, a project level assessment must appreciate the near-term constraints that will face practitioners who attempt to realize the GHG mitigation potential in the forest and agroforestry sectors of their countries. 相似文献
147.
148.
Political pressures exist to increase the economic efficiency of timber management and production on the national forests
managed by the USDA Forest Service. There is growing belief both outside and within the Forest Service that current levels
of timber production, and most particularly uneconomic timber production, should be reduced. Many argue that eliminating uneconomic
timber management programs will both save money and reduce environmental degradation. This article traces the political evolution
of the focus on economic efficiency in timber production and explores the political-institutional factors that are shaping
the current policy debate. The below-cost issue is less about economic efficiency than it is about political advantage and
alternative political visions of the societal role of the nation's national forests now and in the future. 相似文献
149.
150.
Lloyd C. Irland 《Environmental management》1980,4(5):381-389
The eastern spruce budworm is a major forest pest over the continental range of the spruce-fir forest ecosystem and its southern ecotonal fringes in Canada and the northeastern United States. The current budworm outbreak illustrates the difficulty of arriving at economically sound and publicly acceptable forest pest control policies. Policies ranging from no use of chemical control to annual widespread crop protection have been adopted. There is no single all-around best policy for spruce budworm control. Chemical spray programs have demonstrably slowed the normal progress of mortality due to budworm, but have not eradicated the pest. Where industry remains heavily dependent on a fully utilized spruce-fir forest, no easy, low-cost solutions to the budworm problem exist. Reliance on spraying will have to be reduced and plans made to utilize higher levels of tree mortality and to manage the forest for lower future vulnerability. 相似文献