Ecoregion

Summary

An ecoregion (ecological region) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation (largely undefined at this point). Ecoregions are also known as "ecozones" ("ecological zones"), although that term may also refer to biogeographic realms. Three caveats are appropriate for all bio-geographic mapping approaches. Firstly, no single bio-geographic framework is opti

Official source

https://en.wikipedia.org/wiki/Ecoregion

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Stability of spatial patterns in water chemistry across temperate ecoregions

Camille Roland Marie Minaudo

Human activity has polluted freshwater ecosystems across the planet, harming biodiversity, human health, and the economy. Improving water quality depends on identifying pollutant sources in river networks, but pollutant concentrations fluctuate in time. Continuous monitoring of many points in river networks is expensive, impeding progress in developing countries where water quality is degrading fastest. In this study, we analyzed 4523 water chemistry time series of ten parameters (NO3-, PO43-, TP, DOC, SO42-, Cl-, Na+, Ca2+, Mg2+, K+) across four temperate ecoregions in France (ca. 560 000 km(2)). We quantified the spatial stability of water chemistry across the monitoring stations using rank correlations between instantaneous concentrations and water quality metrics derived from 6-year time series (2010-2015). The strength of this rank correlation represents how well a water quality evaluation metric can be characterized with a single sampling for a given water quality parameter. Results show that a single sampling captured a mean of 88% of the spatial variability of these parameters, across ecoregions with different climate and land-use conditions. The spatial stability resulted both from high spatial variability among sites and high temporal synchrony among time series. These findings demonstrate that infrequent but spatially dense water sampling can achieve two of the major goals of water quality monitoring: identify pollutant sources and inform ideal locations for conservation and restoration interventions.

IOP PUBLISHING LTD2019

We estimate future wildfire activity over the western United States during the mid-21st century (2046-2065), based on results from 15 climate models following the A1B scenario. We develop fire prediction models by regressing meteorological variables from the current and previous years together with fire indexes onto observed regional area burned. The regressions explain 0.25-0.60 of the variance in observed annual area burned during 1980-2004, depending on the ecoregion. We also parameterize daily area burned with temperature, precipitation, and relative humidity. This approach explains similar to 0.5 of the variance in observed area burned over forest ecoregions but shows no predictive capability in the semi-arid regions of Nevada and California. By applying the meteorological fields from 15 climate models to our fire prediction models, we quantify the robustness of our wildfire projections at midcentury. We calculate increases of 24-124% in area burned using regressions and 63-169% with the parameterization. Our projections are most robust in the southwestern desert, where all GCMs predict significant (p < 0.05) meteorological changes. For forested ecoregions, more GCMs predict significant increases in future area burned with the parameterization than with the regressions, because the latter approach is sensitive to hydrological variables that show large inter-model variability in the climate projections. The parameterization predicts that the fire season lengthens by 23 days in the warmer and drier climate at midcentury. Using a chemical transport model, we find that wildfire emissions will increase summertime surface organic carbon aerosol over the western United States by 46-70% and black carbon by 20-27% at midcentury, relative to the present day. The pollution is most enhanced during extreme episodes: above the 84th percentile of concentrations, OC increases by similar to 90% and BC by similar to 50%, while visibility decreases from 130 km to 100 km in 32 Federal Class 1 areas in Rocky Mountains Forest. (C) 2013 Elsevier Ltd. All rights reserved.

Pergamon-Elsevier Science Ltd2013

We study the observed geographic distribution of freshwater fish species in the Mississippi-Missouri river system, focusing on the size and spatial distribution of geographic ranges. We use a particular metric of geographic distribution known as environmental resistance, a biogeographic index that quantifies the pointwise average spatial loss of community similarity to identify biogeographic regions of the river basin. Empirical patterns are compared with the results of a neutral metacommunity model in which local fish communities are interconnected through the ecological corridors provided by the river networks. Because neutral theory assumes that all individuals across all the species are functionally equivalent, the comparison is aimed to quantify how much of the geographic range patterns are the result of species' similarity rather than species differences, thus searching for an ecological null model for the analysis of biogeographic range. We also analyze how river network topology affects the spatial arrangement of species. Our results suggest that broad patterns of geographic range of freshwater fish in the Mississippi-Missouri can be explained simply by neutral dynamics engaged in river topology and competition for resources among species without invoking mechanisms that involve asymmetric interspecific interactions.

American Geophysical Union2009

Pergamon-Elsevier Science Ltd2013