The direct and indirect effects of watershed land use and soil type on stream water metal concentrations

2016 ◽  
Vol 52 (10) ◽  
pp. 7711-7725 ◽  
Author(s):  
M. Taka ◽  
J. Aalto ◽  
J. Virkanen ◽  
M. Luoto
Keyword(s):  
Land Use ◽  
Soil Type ◽  
Indirect Effects ◽  
Stream Water ◽  
Direct And Indirect Effects ◽  
Metal Concentrations ◽  
Watershed Land Use ◽  
Water Metal

scholarly journals Using occupancy models to assess the direct and indirect impacts of agricultural expansion on species’ populations

2020 ◽  
Vol 29 (13) ◽  
pp. 3669-3688
Author(s):  
Asunción Semper-Pascual ◽  
Julieta Decarre ◽  
Matthias Baumann ◽  
Micaela Camino ◽  
Yamil Di Blanco ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Direct Effect ◽  
Indirect Effects ◽  
Agricultural Land ◽  
Conservation Strategies ◽  
Agricultural Expansion ◽  
Direct And Indirect Effects ◽  
Occupancy Models ◽  
Occupancy Modelling

Abstract Land-use change is a global threat to biodiversity, but how land-use change affects species beyond the direct effect of habitat loss remains poorly understood. We developed an approach to isolate and map the direct and indirect effects of agricultural expansion on species of conservation concern, using the threatened giant anteater (Myrmecophaga tridactyla) in the Gran Chaco as an example. We reconstructed anteater occupancy change between 1985 and 2015 by fitting single-season occupancy models with contemporary camera-trap data and backcasting the models to 1985 and 2000 land-cover/use maps. Based on this, we compared the area of forest loss (direct effect of agricultural expansion) with the area where forests remained but occupancy still declined (indirect effect of agricultural expansion). Anteater occupancy decreased substantially since 1985, particularly after 2000 when agriculture expanded rapidly. Between 1985 and 2015, ~ 64,000 km2 of forest disappeared, yet occupancy declined across a larger area (~ 102,000 km2), extending far into seemingly untransformed habitat. This suggests that widespread sink habitat has emerged due to agricultural land-use change, and that species may lose their habitat through direct and indirect effects of agricultural expansion, highlighting the urgent need for broad-scale conservation planning in the Chaco. Appropriate management responses could proactively protect more habitat where populations are stable, and restore habitat or address causes of mortality in areas where declines occur. Our work also highlights how occupancy modelling combined with remote sensing can help to detect the direct and indirect effects of agricultural expansion, providing guidance for spatially targeting conservation strategies to halt extinctions.

scholarly journals Direct and indirect effects of land-use intensity on plant communities across elevation in semi-natural grasslands

2020 ◽  
Author(s):  
Oksana Y. Buzhdygan ◽  
Britta Tietjen ◽  
Svitlana S. Rudenko ◽  
Volodymyr A. Nikorych ◽  
Jana S. Petermann
Keyword(s):  
Land Use ◽  
Plant Communities ◽  
Indirect Effects ◽  
Elevation Gradient ◽  
Grazing Intensity ◽  
Bare Soil ◽  
Direct And Indirect Effects ◽  
Natural Grasslands ◽  
Soil Exposure ◽  
Effects Of Land Use

AbstractGrassland biodiversity is among the most vulnerable to land use. How to best manage semi-natural grasslands for maintaining biodiversity is still unclear in many cases because processes may depend on environmental conditions and indirect effects are rarely considered. Here we evaluate the relative importance of direct and indirect effects of grazing intensity on plant communities along an elevational gradient on a large topographic scale in the Eastern Carpathians in Ukraine. We sampled 31 semi-natural grasslands exposed to cattle grazing in two years. Within each grassland site we measured plant community properties such as the number of species, functional groups, and the proportion of undesirable weeds. In addition, we recorded cattle density (as proxy for grazing intensity), soil properties (bare soil exposure, soil organic carbon, and soil pH) and densities of soil decomposers (earthworms and soil microorganisms). We used structural equation modelling to explore direct and indirect effects of grazing intensity on plant communities along the elevation gradient. We found that cattle density decreased plant species and functional diversity but increased the proportion of undesirable weeds. Some of these effects were directly linked to grazing intensity (i.e., species richness), while others (i.e., functional diversity and proportion of undesirable weeds) were mediated via bare soil exposure. Although grazing intensity decreased with elevation, the effects of grazing on the plant community did not change along the elevation gradient. Generally, elevation had a strong positive direct effect on plant species richness as well as a negative indirect effect, mediated via altered soil acidity and decreased decomposer density. Our results indicate that plant diversity and composition are controlled by the complex interplay among grazing intensity and changing environmental conditions along elevation. Furthermore, we found lower soil pH, organic carbon and decomposer density with elevation, indicating that the effects of grazing on soil and related ecosystem functions and services in semi-natural grasslands may be more pronounced with elevation. This demonstrates that we need to account for environmental gradients when attempting to generalize effects of land-use intensity on biodiversity.

Influence of watershed land use and riparian characteristics on biological indicators of stream water quality in southeastern Brazil

2016 ◽  
Vol 216 ◽  
pp. 333-339 ◽  
Author(s):  
Marcel Okamoto Tanaka ◽  
Andréa Lúcia Teixeira de Souza ◽  
Luiz Eduardo Moschini ◽  
Alexandre Kannebley de Oliveira
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Stream Water ◽  
Biological Indicators ◽  
Southeastern Brazil ◽  
Stream Water Quality ◽  
Watershed Land Use
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