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Wagner T Bremigan MT Cheruvelil KS Soranno PA Nate NA Breck JE 《Environmental monitoring and assessment》2007,130(1-3):437-454
The ecoregion and watershed frameworks are landscape-based classifications that have been used to group waterbodies with respect to measures of community structure; however, they have yet to be evaluated for grouping lakes for demographic characteristics of fish populations. We used a multilevel modeling approach to determine if variability in mean fish length at age could be partitioned by ecoregions and watersheds. For the ecoregions analysis, we then examined if within-ecoregion variability could be explained by local water quality and lake morphometry characteristics. We used data from agency surveys conducted during 1974-1984 for age 2 and 3 fish of seven common warm and coolwater fish species. Variance in mean length at age between ecoregions for all species was not significant, and between-watershed variance estimates were only significant in 3 out of 14 analyses; however, the total amount of variation between watersheds was very small (ranging from 1.8% to 3.7% of the total variance), indicating that ecoregions and watersheds were ineffective in partitioning variability in mean length at age. Within ecoregions, water quality and lake morphometric characteristics accounted for 2%-23% of the variation in mean length at age. Measures of lake productivity were the most common significant covariates, with mean length at age increasing with increasing lake productivity. Much of the variability in mean length at age was not accounted for, suggesting that other local factors such as biotic interactions, fish density, and exploitation are important. The results indicate that the development of an effective regional framework for managing inland lakes will require a substantial effort to understand sources of demographic variability and that managers should not rely solely on ecoregions or watersheds for grouping lakes with similar growth rates. 相似文献
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Comparing Hydrogeomorphic Approaches to Lake Classification 总被引:1,自引:1,他引:0
A classification system is often used to reduce the number of different ecosystem types that governmental agencies are charged with monitoring and managing. We compare the ability of several different hydrogeomorphic (HGM)—based classifications to group lakes for water chemistry/clarity. We ask: (1) Which approach to lake classification is most successful at classifying lakes for similar water chemistry/clarity? (2) Which HGM features are most strongly related to the lake classes? and, (3) Can a single classification successfully classify lakes for all of the water chemistry/clarity variables examined? We use univariate and multivariate classification and regression tree (CART and MvCART) analysis of HGM features to classify alkalinity, water color, Secchi, total nitrogen, total phosphorus, and chlorophyll a from 151 minimally disturbed lakes in Michigan USA. We developed two MvCART models overall and two CART models for each water chemistry/clarity variable, in each case comparing: local HGM characteristics alone and local HGM characteristics combined with regionalizations and landscape position. The combined CART models had the highest strength of evidence (ωi range 0.92–1.00) and maximized within class homogeneity (ICC range 36–66%) for all water chemistry/clarity variables except water color and chlorophyll a. Because the most successful single classification was on average 20% less successful in classifying other water chemistry/clarity variables, we found that no single classification captures variability for all lake responses tested. Therefore, we suggest that the most successful classification (1) is specific to individual response variables, and (2) incorporates information from multiple spatial scales (regionalization and local HGM variables). 相似文献
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Grouping Lakes for Water Quality Assessment and Monitoring: The Roles of Regionalization and Spatial Scale 总被引:1,自引:0,他引:1
Cheruvelil KS Soranno PA Bremigan MT Wagner T Martin SL 《Environmental management》2008,41(3):425-440
Regionalization frameworks cluster geographic data to create contiguous regions of similar climate, geology and hydrology
by delineating land into discrete regions, such as ecoregions or watersheds, often at several spatial scales. Although most
regionalization schemes were not originally designed for aquatic ecosystem classification or management, they are often used
for such purposes, with surprisingly few explicit tests of the relative ability of different regionalization frameworks to
group lakes for water quality monitoring and assessment. We examined which of 11 different lake grouping schemes at two spatial
scales best captures the maximum amount of variation in water quality among regions for total nutrients, water clarity, chlorophyll,
overall trophic state, and alkalinity in 479 lakes in Michigan (USA). We conducted analyses on two data sets: one that included
all lakes and one that included only minimally disturbed lakes. Using hierarchical linear models that partitioned total variance
into within-region and among-region components, we found that ecological drainage units and 8-digit hydrologic units most
consistently captured among-region heterogeneity at their respective spatial scales using all lakes (variation among lake
groups = 3% to 50% and 12% to 52%, respectively). However, regionalization schemes capture less among-region variance for
minimally disturbed lakes. Diagnostics of spatial autocorrelation provided insight into the relative performance of regionalization
frameworks but also demonstrated that region size is only partly responsible for capturing variation among lakes. These results
suggest that regionalization schemes can provide useful frameworks for lake water quality assessment and monitoring but that
we must identify the appropriate spatial scale for the questions being asked, the type of management applied, and the metrics
being assessed. 相似文献
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