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1.
Ecological regionalization is a base for rational management and sustainable utilization of ecosystems and natural resources. It can provide a scientific basis for constructing healthy ecological environments and making policies of environmental management. In this paper, based on synthetic analysis of the characteristics of the ecology and environments of China, the principles of ecological regionalization are discussed, and indices and nomenclature of ecological regionalization are proposed. The ecoregions on a national scale are divided. The results show that there are 3 domains, 13 ecoregions and 57 ecodistricts. The present scheme can be used as a framework for ecosystem assessment and management. Based on the ecoregions, measurements of management for forest, grassland, agriculture and wetland ecosystems are recommended. The experience and information can be used within and beyond the national scale for land-use planning, biodiversity conservation and ecosystem restoration. 相似文献
2.
Our lack of understanding of relationships between stream biotic communities and surrounding landscape conditions makes it
difficult to determine the spatial scale at which management practices are best assessed. We investigated these relationships
in the Minnesota River Basin, which is divided into major watersheds and agroecoregions which are based on soil type, geologic parent material, landscape slope steepness, and climatic factors affecting crop productivity.
We collected macroinvertebrate and stream habitat data from 68 tributaries among three major watersheds and two agroecoregions.
We tested the effectiveness of the two landscape classification systems (i.e., watershed, agroecoregion) in explaining variance
in habitat and macroinvertebrate metrics, and analyzed the relative influence on macroinvertebrates of local habitat versus
regional characteristics. Macroinvertebrate community composition was most strongly influenced by local habitat; the variance
in habitat conditions was best explained at the scale of intersection of major watershed and agroecoregion (i.e., stream habitat
conditions were most homogeneous within the physical regions of intersection of these two landscape classification systems).
Our results are consistent with findings of other authors that most variation in macroinvertebrate community data from large
agricultural catchments is attributable to local physical conditions. Our results are the first to test the hypothesis and
demonstrate that the scale of intersection best explains these variances. The results suggest that management practices adjusted
for both watershed and ecoregion characteristics, with the goal of improving physical habitat characteristics of local streams,
may lead to better basin-wide water quality conditions and stream biological integrity. 相似文献
3.
Regional Representativeness of Swedish Reference Lakes 总被引:1,自引:1,他引:0
Richard K. Johnson 《Environmental management》1999,23(1):115-124
/ Recent focus has been placed on ecoregion delineations for providing an appropriate framework for monitoring and assessment of region-specific attainable water/habitat quality. Using an ecoregion approach to stratify variance, this study was conducted to determine whether earlier (subjectively) selected Swedish reference lakes may be considered as regionally representative reference sites when compared with a randomly selected lake population. Predictive modeling by discriminant function analysis with lakes classified by ecoregion and lake surface area and six physicochemical variables showed that the greater majority of reference lakes may be considered as regionally representative. The highest proportion of lake "misclassifications" occurred in the boreonemoral ecoregion, a relatively diverse ecoregion of southern Sweden. This apparent bias may be in part be due to the criteria used in selecting regional reference lakes. In the earlier selection of reference lakes emphasis was placed on lakes not being adversely affected by land usage or pollutant discharges, consequently forest lakes were often overrepresented and sites in agricultural areas underrepresented in the selected reference sites. As a complement to predictive modeling, PCA ordination showed the placement of reference lakes within the random lake population and indicated where reference sites might be missing along potentially important ecological gradients. KEY WORDS: Regionalization; Ecoregion; Representativeness; Reference; Ordination; Modeling; Temperate lakes 相似文献
4.
A.R. Mittelstet D.E. Storm 《Journal of the American Water Resources Association》2016,52(6):1297-1310
Classic agricultural‐conservation practices may not address decades of phosphorus (P) accumulation, known as legacy P. Identifying and quantifying legacy P sources are necessary to identify the most cost‐efficient conservation practices. A method was developed to identify and quantify legacy P at the watershed scale using a mass‐balance approach and uncertainty analysis. The method was applied to two nutrient‐rich watersheds in northeast Oklahoma and northwest Arkansas. Each P import and export to and from the two watersheds was identified and quantified using a probability distribution and uncertainty analysis. The P retained in the soils, reservoirs, and stream systems were estimated from 1925 to 2015. Over 8.5 and 6.1 kg/ha/year of P were added to the Illinois River and Eucha‐Spavinaw watersheds with 53 and 55% from poultry production, respectively. Other major historical sources were attributed to human population and commercial fertilizer. Though currently the net addition of P in the watersheds is small due to the export of approximately 90% of the poultry litter, historically only 14‐19% of all P imported to the Illinois River and Eucha‐Spavinaw watersheds was removed via the reservoir spillways, poultry litter, and food exports. The majority of the retained P is located in the soil, 3.6‐5.8 kg/ha/year, and stream systems, 0.01‐3.0 per ha/year. 相似文献
5.
G. Darrel Jenerette Jay Lee David W. Waller Robert E. Carlson 《Environmental management》2002,29(1):67-75
The ecoregion concept is a popular method of understanding the spatial distribution of the environment', however, it has yet
to be adequately demonstrated that the environment is distributed in accordance with these bounded units. In this paper, we
generated a testable hypothesis based on the current usage of ecoregions: the ecoregion classification will allow for discrimination
between lakes of different water quality. The ecoregion classification should also be more effective better than a comparably
scaled classification based on political boundaries, land-use class, or random grouping. To test this hypothesis we used the
Environmental Monitoring and Assessment Program (EMAP) lake water chemistry data from the northeast United States. The water
chemistry data were reduced to four components using principal component analysis. For comparison to an optimal grouping of
these data we used K-means cluster analysis to define the extent at which these lakes could be segregated into distinct classes.
Jackknifed discriminant analysis was used to determine the classification rate of ecoregions, the three alternative spatial
classification methods, and the clustering algorithm. The classification based on ecoregions was successful for 35% of the
lakes included in this study, in comparison to the clustered groups accuracy of 98%. These results suggest that the large
scale spatial distribution of ecosystem types is more complicated than that suggested by the present ecoregion boundaries.
Further tests of ecoregion delineations are needed and alternative large-scale management strategies should be investigated. 相似文献
6.
Analysis of macroinvertebrate assemblages in relation to environmental gradients among lotic habitats of California's Central Valley 总被引:3,自引:0,他引:3
Griffith MB Husby P Hall RK Kaufmann PR Hill BH 《Environmental monitoring and assessment》2003,82(3):281-309
We assessed relationships between environmental characteristicsand macroinvertebrate assemblages in lotic habitats of California's Central Valley with community metric and multivariate statistical approaches. Using canonical ordinationanalyses, we contrasted results when assemblage structure was assessed with macroinvertebrate metrics, as suggested for use inindices of biotic integrity, or with genera abundances. Our objectives were to identify metrics or taxa diagnostic of loticenvironmental stressors and compare the capacity of theseapproaches to detect stressors in order to suggest how they mightbe used to diagnose stressors. For macroinvertebrate metrics,redundancy analysis (RDA) extracted three axes correlated withchannel morphology and substrates. For genera abundances, canonical correspondence analysis (CCA) extracted two axescorrelated with soluble salts and with channel morphology andsubstrates but did not separate these gradients onto differentaxes. Cluster analyses identified five RDA and five CCA sitegroups, which exhibited differences for environmental variables,metrics, or genera abundances, and agreement between the analysesin partitioning of sites was greater than if sites were partitioned randomly. These approaches differ in their abilityto detect environmental stressors, because they measure differentaspects of assemblages and would be complementary in design ofnew metrics diagnostic of stressors. 相似文献
7.
VALUING ECOSYSTEM SERVICES OF CHILEAN TEMPERATE RAINFORESTS 总被引:1,自引:0,他引:1
LAURA NAHUELHUAL PABLO DONOSO ANTONIO LARA DAISY NÚÑEZ CARLOS OYARZÚN EDUARDO NEIRA 《Environment, Development and Sustainability》2007,9(4):481-499
The Valdivian Rainforest Ecoregion (35°–48° S) in southern South America is among the ecosystems with highest conservation
priority worldwide due to its rich diversity, degree of endemism, and critical conservation status. Temperate rainforests
in this vast area are essential as source of biological resources and to maintain different ecosystem services which remain
largely unmeasured and unvalued. Consequently, the benefits they provide are not reflected in decision-making regarding forest
management and conservation. Based on existing studies and results from ongoing research we describe selected ecosystem services
and provide estimates of their economic value. Timber benefits for secondary forests expressed as net present stumpage values
were US$ 3742 ha−1 and US$ 3093 ha−1 for sustainable forest management (SFM) and unsustainable harvesting, respectively. Timber benefits for old growth forests␣equaled
US$ 4546 ha−1 and US$ 5718 ha−1, for SFM and unsustainable harvesting, respectively, using an 8% discount rate. Annual benefits from recreation were US$
1.6 ha−1 and US$ 6.3 ha−1 for the two most important national parks located in the study area. The annual value of maintaining soil fertility was US$
26.3 ha−1 using the replacement cost of nutrient losses due to soil erosion. The annual economic value of water supply for human consumption
using the production function method was US$ 235 ha−1. These results provide valuable information on the kind and magnitude of values that could be relevant in decision-making
concerning conservation and management of native forests in the Valdivian Rainforest Ecoregion. 相似文献
8.
9.
Gajanan Bhat John Bergstrom R. Jeff Teasley J. M. Bowker H. Ken Cordell 《Environmental management》1998,22(1):69-77
/ This paper describes a framework for estimating the economic value of outdoor recreation across different ecoregions. Ten ecoregions in the continental United States were defined based on similarly functioning ecosystem characters. The individual travel cost method was employed to estimate recreation demand functions for activities such as motor boating and waterskiing, developed and primitive camping, coldwater fishing, sightseeing and pleasure driving, and big game hunting for each ecoregion. While our ecoregional approach differs conceptually from previous work, our results appear consistent with the previous travel cost method valuation studies.KEY WORDS: Recreation; Ecoregion; Travel cost method; Truncated Poisson model 相似文献
10.
Mapped environmental classifications are defined using various procedures, but there has been little evaluation of the differences
in their ability to discriminate variation in independent ecological characteristics. We tested the performance of environmental
classifications of the streams and rivers of France that had been defined from the same environmental data using geographic
regionalization and numerical classification of individual river valley segments. Test data comprised invertebrate assemblages,
water chemistry, and hydrological indexes obtained from sites throughout France. Classification performance was measured by
analysis of similarity (ANOSIM). Geometric regions defined by a regular grid and without regard to environmental variables
and a posteriori classifications based on clustering the test datasets defined lower and upper bounds of performance for a
given number of classes. Differences in classification performances were generally small. The ANOSIM statistics for the a
posteriori classifications were around twice that of all environmental classifications, including geometrically defined regions.
The hydro-ecoregions performed slightly better for the invertebrate data and the network classification performed slightly
better for the chemistry and hydrological data. Our results indicate that environmental classifications that are defined using
different procedures can be comparable in terms of their ability to discriminate variation of ecological characteristics and
that alleged differences in performance arising from different classification procedures can be small relative to unexplained
variation. We conclude that definition procedures might have little effect on the performance of large-scale environmental
classifications and decisions over which procedures to use should be based primarily on pragmatic considerations. 相似文献