共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
林地产权政策是决定资源配置效率的基础条件。对临安示范林地区研究基点河桥乡的林地产权政策、林地流转的基本情况及农户对林地产权的意愿进行了介绍,找出了现行政策存在的问题,并提出了一套科学合理的适合当地水平的林地产权政策方案。 相似文献
3.
Yangjian Zhang Hong S. He William D. Dijak Jian Yang Stephen R. Shifley Brian J. Palik 《Environmental management》2009,44(2):312-323
To achieve the overall objective of restoring natural environment and sustainable resource usability, each forest management
practice effect needs to be predicted using a simulation model. Previous simulation efforts were typically confined to public
land. Comprehensive forest management practices entail incorporating interactions between public and private land. To make
inclusion of private land into management planning feasible at the regional scale, this study uses a new method of combining
Forest Inventory and Analysis (FIA) data with remotely sensed forest group data to retrieve detailed species composition and
age information for the Missouri Ozark Highlands. Remote sensed forest group and land form data inferred from topography were
integrated to produce distinct combinations (ecotypes). Forest types and size classes were assigned to ecotypes based on their
proportions in the FIA data. Then tree species and tree age determined from FIA subplots stratified by forest type and size
class were assigned to pixels for the entire study area. The resulting species composition map can improve simulation model
performance in that it has spatially explicit and continuous information of dominant and associated species, and tree ages
that are unavailable from either satellite imagery or forest inventory data. In addition, the resulting species map revealed
that public land and private land in Ozark Highlands differ in species composition and stand size. Shortleaf pine is a co-dominant
species in public land, whereas it becomes a minor species in private land. Public forest is older than private forest. Both
public and private forests have deviated from historical forest condition in terms of species composition. Based on possible
reasons causing the deviation discussed in this study, corresponding management avenues that can assist in restoring natural
environment were recommended. 相似文献
4.
Identifying Influences on Model Uncertainty: An Application Using a Forest Carbon Budget Model 总被引:2,自引:0,他引:2
Uncertainty is an important consideration for both developers and users of environmental simulation models. Establishing quantitative
estimates of uncertainty for deterministic models can be difficult when the underlying bases for such information are scarce.
We demonstrate an application of probabilistic uncertainty analysis that provides for refinements in quantifying input uncertainty
even with little information. Uncertainties in forest carbon budget projections were examined with Monte Carlo analyses of
the model FORCARB. We identified model sensitivity to range, shape, and covariability among model probability density functions,
even under conditions of limited initial information. Distributional forms of probabilities were not as important as covariability
or ranges of values. Covariability among FORCARB model parameters emerged as a very influential component of uncertainty,
especially for estimates of average annual carbon flux. 相似文献
5.
UL94水平垂直燃烧仪,设计为对设备和器具部件材料的可燃性能试验,众多应用于最终用途产品的易燃性能、燃烧速率、火焰蔓延、燃烧强度均可被检测.目前已经被广泛应用于该类行业。 相似文献
6.
7.
农林综合开发出新意——以虞山宝岩高科技农林生态观光园为例 总被引:1,自引:0,他引:1
森林资源可持续利用与山区综合开发是21世纪林业关注的热点。本文通过介绍虞山宝岩高科技农林生态观光园的规划,旨在探讨新形式下农林综合开发的新思路 相似文献
8.
Kenneth J. Tobin Marvin E. Bennett 《Journal of the American Water Resources Association》2009,45(1):253-271
Abstract: Both ground rain gauge and remotely sensed precipitation (Next Generation Weather Radar – NEXRAD Stage III) data have been used to support spatially distributed hydrological modeling. This study is unique in that it utilizes and compares the performance of National Weather Service (NWS) rain gauge, NEXRAD Stage III, and Tropical Rainfall Measurement Mission (TRMM) 3B42 (Version 6) data for the hydrological modeling of the Middle Nueces River Watershed in South Texas and Middle Rio Grande Watershed in South Texas and northern Mexico. The hydrologic model chosen for this study is the Soil and Water Assessment Tool (SWAT), which is a comprehensive, physical‐based tool that models watershed hydrology and water quality within stream reaches. Minor adjustments to selected model parameters were applied to make parameter values more realistic based on results from previous studies. In both watersheds, NEXRAD Stage III data yields results with low mass balance error between simulated and actual streamflow (±13%) and high monthly Nash‐Sutcliffe efficiency coefficients (NS > 0.60) for both calibration (July 1, 2003 to December 31, 2006) and validation (2007) periods. In the Middle Rio Grande Watershed NEXRAD Stage III data also yield robust daily results (time averaged over a three‐day period) with NS values of (0.60‐0.88). TRMM 3B42 data generate simulations for the Middle Rio Grande Watershed of variable qualtiy (MBE = +13 to ?16%; NS = 0.38‐0.94; RMSE = 0.07‐0.65), but greatly overestimates streamflow during the calibration period in the Middle Nueces Watershed. During the calibration period use of NWS rain gauge data does not generate acceptable simulations in both watersheds. Significantly, our study is the first to successfully demonstrate the utility of satellite‐estimated precipitation (TRMM 3B42) in supporting hydrologic modeling with SWAT; thereby, potentially extending the realm (between 50°N and 50°S) where remotely sensed precipitation data can support hydrologic modeling outside of regions that have modern, ground‐based radar networks (i.e., much of the third world). 相似文献
9.
Landscape spatial patterns have increasingly been considered to be essential for environmental planning and resources management.
In this study, we proposed a hierarchical approach for landscape classification and evaluation by characterizing landscape
spatial patterns across different hierarchical levels. The case study site is the Red Hills region of northern Florida and
southwestern Georgia, well known for its biodiversity, historic resources, and scenic beauty. We used one Landsat Enhanced
Thematic Mapper image to extract land-use/-cover information. Then, we employed principal-component analysis to help identify
key class-level landscape metrics for forests at different hierarchical levels, namely, open pine, upland pine, and forest
as a whole. We found that the key class-level landscape metrics varied across different hierarchical levels. Compared with
forest as a whole, open pine forest is much more fragmented. The landscape metric, such as CONTIG_MN, which measures whether
pine patches are contiguous or not, is more important to characterize the spatial pattern of pine forest than to forest as
a whole. This suggests that different metric sets should be used to characterize landscape patterns at different hierarchical
levels. We further used these key metrics, along with the total class area, to classify and evaluate subwatersheds through
cluster analysis. This study demonstrates a promising approach that can be used to integrate spatial patterns and processes
for hierarchical forest landscape planning and management. 相似文献
10.
Spatio-Temporal Variability of Soil Respiration of Forest Ecosystems in China: Influencing Factors and Evaluation Model 总被引:1,自引:0,他引:1
Ze-Mei Zheng Gui-Rui Yu Xiao-Min Sun Sheng-Gong Li Yue-Si Wang Ying-Hong Wang Yu-Ling Fu Qiu-Feng Wang 《Environmental management》2010,46(4):633-642
Understanding the influencing factors of the spatio-temporal variability of soil respiration (R
s) across different ecosystems as well as the evaluation model of R
s is critical to the accurate prediction of future changes in carbon exchange between ecosystems and the atmosphere. R
s data from 50 different forest ecosystems in China were summarized and the influences of environmental variables on the spatio-temporal
variability of R
s were analyzed. The results showed that both the mean annual air temperature and precipitation were weakly correlated with
annual R
s, but strongly with soil carbon turnover rate. R
s at a reference temperature of 0°C was only significantly and positively correlated with soil organic carbon (SOC) density
at a depth of 20 cm. We tested a global-scale R
s model which predicted monthly mean R
s (R
s,monthly) from air temperature and precipitation. Both the original model and the reparameterized model poorly explained the monthly
variability of R
s and failed to capture the inter-site variability of R
s. However, the residual of R
s,monthly was strongly correlated with SOC density. Thus, a modified empirical model (TPS model) was proposed, which included SOC density
as an additional predictor of R
s. The TPS model explained monthly and inter-site variability of R
s for 56% and 25%, respectively. Moreover, the simulated annual R
s of TPS model was significantly correlated with the measured value. The TPS model driven by three variables easy to be obtained
provides a new tool for R
s prediction, although a site-specific calibration is needed for using at a different region. 相似文献
11.
Successful biodiversity conservation does not depend on ecologic knowledge alone. Good conservation policies and policy implementation
tools are equally important. Moreover, the knowledge, skills, and attitudes of local actors, directly in charge of operations
in the field, are a key to successful policy implementation. The connections between policy objectives and their implementation
as well as the involvement of local actors’ efforts in implementing policy objectives largely depend on the governance model
in use. This article assesses the knowledge of local actors in relation to the biodiversity conservation objectives and tools
in Lithuanian forest management. As a main framework for this study, the needs assessment approach was applied. The study
used both in-depth open-ended interviews and follow-up telephone interviews. Two state forest enterprises in Lithuania were
selected as the study sites. The findings indicate that policy objectives in the field of forest biodiversity conservation
and the related tools are well known but not well understood by those in charge of forest biodiversity policy implementation.
To improve the situation, a transition toward adaptive learning and participatory governance as a means of facilitating conservation
efforts is proposed. 相似文献
12.
Yang Yang Theodore A. Endreny David J. Nowak 《Journal of the American Water Resources Association》2011,47(6):1211-1218
Yang, Yang, Theodore A. Endreny, and David J. Nowak, 2011. iTree‐Hydro: Snow Hydrology Update for the Urban Forest Hydrology Model. Journal of the American Water Resources Association (JAWRA) 47(6):1211–1218. DOI: 10.1111/j.1752‐1688.2011.00564.x Abstract: This article presents snow hydrology updates made to iTree‐Hydro, previously called the Urban Forest Effects—Hydrology model. iTree‐Hydro Version 1 was a warm climate model developed by the USDA Forest Service to provide a process‐based planning tool with robust water quantity and quality predictions given data limitations common to most urban areas. Cold climate hydrology routines presented in this update to iTree‐Hydro include: (1) snow interception to simulate the capture of snow by the vegetation canopy, (2) snow unloading to simulate the release of snow triggered by wind, (3) snowmelt to simulate the solid to liquid phase change using a heat budget, and (4) snow sublimation to simulate the solid to gas phase via evaporation. Cold climate hydrology routines were tested with research‐grade snow accumulation and weather data for the winter of 1996‐1997 at Umpqua National Forest, Oregon. The Nash‐Sutcliffe efficiency for open area snow accumulation was 0.77 and the Nash‐Sutcliffe efficiency for under canopy was 0.91. The USDA Forest Service offers iTree‐Hydro for urban forest hydrology simulation through http://www.iTreetools.org . 相似文献
13.
14.
Nigel Dudley 《The Environmentalist》1995,15(3):182-187
Summary A study beyond the political boundaries in planning strategies for long-term management of the global forest estate is presented. Three alternative forest networks are proposed: (1) the genetic-evolutionary network, based around common evolutionary features, thus delineating similar forest types where conservation and management issues are likely to be compatible; (2) the current ecological and environmental network, based around the role that forests play in the wider ecosystem, including regular and irregular migration pathways, networks to absorb the impact of climate change, water filters etc; (3) the human impact network, based on the history of human involvement in the forest and its implications. The practical policy significance of the various networks is discussed in turn.This paper was researched as part of a project carried out for the World Wide Fund for Nature (WWF). Nigel Dudley is an ecologist, based in the UK, with 15 years experience as a consultant for NGOs, local government and international organizations. He is a former director of the Soil Association and now works with Equilibrium Consultants at the above address. For the past five years he has worked closely with WWF on forest conservation projects and has written several reports for the organization, includingForests in trouble: a review of the status of temperate forests worldwide. 相似文献
15.
我国森林公园旅游开发与规划研究综述 总被引:1,自引:0,他引:1
在阅读大量文献资料的基础上,试图从森林公园旅游资源调查与评价、森林公园旅游规划与建设、森林公园旅游产品开发、森林公园旅游资源开发问题与对策、森林公园旅游资源的开发与保护、森林公园景观资产的评估、森林公园旅游解说系统等方面对国内有关森林公园旅游开发与规划的研究进行了系统综述。在此基础上,对中国森林公园旅游开发与规划以后的研究进行了展望。 相似文献
16.
A wildland fire is a serious threat for forest ecosystems in Southern Europe affecting severely and irreversibly regions of significant ecological value as well as human communities. To support decision makers during large-scale forest fire incidents, a multidisciplinary system has been developed that provides rational and quantitative information based on the site-specific circumstances and the possible consequences. The systems architecture consists of several distinct supplementary modules of near real-time satellite monitoring and fire forecast using an integrated framework of satellite Remote Sensing, GIS, and RDBMS technologies equipped with interactive communication capabilities. The system may handle multiple fire ignitions and support decisions regarding dispatching of utilities, equipment, and personnel that would appropriately attack the fire front. The operational system was developed for the region of Penteli Mountain in Attika, Greece, one of the mountain areas in the country most hit by fires. Starting from a real fire incident in August 2000, a scenario is presented to illustrate the effectiveness of the proposed approach. 相似文献
17.
森林旅游是生态旅游的重要形式之一,开展森林旅游已成为一种新的消费时尚,也是当今世界旅游的热点.介绍了神山国家森林公园优越的自然条件、丰富的森林旅游资源和人文旅游资源,分析了目前建设森林公园存在的问题,提出了发展森林旅游的建议. 相似文献
18.
19.
Community-based collaborative groups involved in public natural resource management are assuming greater roles in planning,
project implementation, and monitoring. This entails the capacity of collaborative groups to develop and sustain new organizational
structures, processes, and strategies, yet there is a lack of understanding what constitutes collaborative capacity. In this
paper, we present a framework for assessing collaborative capacities associated with community-based public forest management
in the US. The framework is inductively derived from case study research and observations of 30 federal forest-related collaborative
efforts. Categories were cross-referenced with literature on collaboration across a variety of contexts. The framework focuses
on six arenas of collaborative action: (1) organizing, (2) learning, (3) deciding, (4) acting, (5) evaluating, and (6) legitimizing.
Within each arena are capacities expressed through three levels of social agency: individuals, the collaborative group itself,
and participating or external organizations. The framework provides a language and set of organizing principles for understanding
and assessing collaborative capacity in the context of community-based public forest management. The framework allows groups
to assess what capacities they already have and what more is needed. It also provides a way for organizations supporting collaboratives
to target investments in building and sustaining their collaborative capacities. The framework can be used by researchers
as a set of independent variables against which to measure collaborative outcomes across a large population of collaborative
efforts. 相似文献
20.
Measurement and Management of Human-Induced Patterns of Forest Fragmentation: A Case Study 总被引:1,自引:0,他引:1
Tole L 《Environmental management》2006,37(6):788-801
In many tropical developing countries, the twin pressures of population and poverty are resulting in substantial fragmentation
of forests, increasing the probability of extinction for many species, Forest fragmentation occurs when large contiguous forests
are perforated by small holes or broken up into edges and smaller patches to form a nonforested matrix of open spaces. Thus,
forest fragmentation refers not only to the area of forest cleared, but also to the pattern of this clearance, the resulting
forest’s spatial properties. Both characteristics are important for species survivability. Apart from opening up forests to
many abiotic and biotic influences, fragmentation can affect species dispersal and migration through its effects on forest
connectivity. Landscape ecology conceptualizes connectivity as a gradient of critical thresholds, ranging from the large intact
forest to the small unconnected forest patch. This article reports results from a multiple-scale analysis of forest fragmentation
in Jamaica’s Cockpit Country, an area of once contiguous forest now under threat from human encroachment. Spatial forest data
derived from classification of ETM+ satellite imagery are used to measure fragmentation patterns representing various degrees
of forest connectivity and density. The results suggest that, overall, 81% of the region is in forest. However, fragmentation
patterns also suggest that this forest is riven with extensive perforations indicative of an early stage in the decline of
contiguity. The results provided by the spatial fragmentation model are a first step in the design of effective conservation
and rehabilitation plans for the area. The article concludes with a discussion of possible multiscale management options for
the region. 相似文献