Agricultural land use alters trophic status and population density of deer mice (Peromyscus maniculatus) on the North American Great Plains

2012 ◽  
Vol 90 (7) ◽  
pp. 868-874 ◽  
Author(s):  
A.J. White ◽  
R.G. Poulin ◽  
B. Wissel ◽  
J.L. Doucette ◽  
C.M. Somers

Habitat conversion is among the most important causes of environmental change worldwide, yet relatively little is known about its potential influence on trophic interactions. We investigated the effects of agricultural land use on carbon and nitrogen stable isotope values, trophic status, population density, and body condition of deer mice ( Peromyscus maniculatus (Wagner, 1845)) in a grassland ecosystem. Muscle δ15N (cropland = 7.6‰ ± 1.3‰; hay fields = 7.9‰ ± 1.3‰; native prairie = 7.2‰ ± 2.1‰) from deer mice did not vary with land use despite baseline soil and vegetation δ15N differences. Enrichment of deer mice over vegetation (Δδ15N) was, on average, a full trophic level (~2.5‰) higher on native prairie (6.4‰ ± 1.6‰) than on cropland (3.9‰ ± 2.3‰), and intermediate in hay fields (5.9‰ ± 2.0‰). Relative density of deer mice was more than twofold higher in crop and hay fields compared with native prairie, but body condition did not vary with land use. Our results suggest that agricultural activity caused a shift in the trophic level and relative abundance of a generalist grassland omnivore. Soil and vegetation δ15N reflected anthropogenic N inputs to agricultural fields but were not useful as general markers of habitat use in this study.

Land ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 24
Author(s):  
Mariana Vallejo ◽  
M. Isabel Ramírez ◽  
Alejandro Reyes-González ◽  
Jairo López-Sánchez ◽  
Alejandro Casas

The Tehuacán-Cuicatlán Valley, Mexico, is the semiarid region with the richest biodiversity of North America and was recently recognized as a UNESCO's World Heritage site. Original agricultural practices remain to this day in agroforestry systems (AFS), which are expressions of high biocultural diversity. However, local people and researchers perceive a progressive decline both in natural ecosystems and AFS. To assess changes in location and extent of agricultural land use, we carried out a visual interpretation of very-high resolution imagery and field work, through which we identified AFS and conventional agricultural systems (CAS) from 1995 to 2003 and 2012. We analyzed five communities, representative of three main ecological and agricultural zones of the region. We assessed agricultural land use changes in relation to conspicuous landscape features (relief, rivers, roads, and human settlements). We found that natural ecosystems cover more than 85% of the territory in each community, and AFS represent 51% of all agricultural land. Establishment and permanence of agricultural lands were strongly influenced by gentle slopes and the existence of roads. Contrary to what we expected, we recorded agricultural areas being abandoned, thus favoring the regeneration of natural ecosystems, as well as a 9% increase of AFS over CAS. Agriculture is concentrated near human settlements. Most of the studied territories are meant to preserve natural ecosystems, and traditional AFS practices are being recovered for biocultural conservation.


Land ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 364
Author(s):  
Sahar Shahpari ◽  
Janelle Allison ◽  
Matthew Tom Harrison ◽  
Roger Stanley

Agricultural land-use change is a dynamic process that varies as a function of social, economic and environmental factors spanning from the local to the global scale. The cumulative regional impacts of these factors on land use adoption decisions by farmers are neither well accounted for nor reflected in agricultural land use planning. We present an innovative spatially explicit agent-based modelling approach (Crop GIS-ABM) that accounts for factors involved in farmer decision making on new irrigation adoption to enable land-use predictions and exploration. The model was designed using a participatory approach, capturing stakeholder insights in a conceptual model of farmer decisions. We demonstrate a case study of the factors influencing the uptake of new irrigation infrastructure and land use in Tasmania, Australia. The model demonstrates how irrigated land-use expansion promotes the diffusion of alternative crops in the region, as well as how coupled social, biophysical and environmental conditions play an important role in crop selection. Our study shows that agricultural land use reflected the evolution of multiple simultaneous interacting biophysical and socio-economic drivers, including soil and climate type, crop and commodity prices, and the accumulated effects of interactive decisions of farmers.


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