Farming and the Fate of Wild Nature

Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
Science (Impact Factor: 33.61). 02/2005; 307(5709):550-5. DOI: 10.1126/science.1106049
Source: PubMed


World food demand is expected to more than double by 2050. Decisions about how to meet this challenge will have profound effects on wild species and habitats. We show that farming is already the greatest extinction threat to birds (the best known taxon), and its adverse impacts look set to increase, especially in developing countries. Two competing solutions have been proposed: wildlife-friendly farming (which boosts densities of wild populations on farmland but may decrease agricultural yields) and land sparing (which minimizes demand for farmland by increasing yield). We present a model that identifies how to resolve the trade-off between these approaches. This shows that the best type of farming for species persistence depends on the demand for agricultural products and on how the population densities of different species on farmland change with agricultural yield. Empirical data on such density-yield functions are sparse, but evidence from a range of taxa in developing countries suggests that high-yield farming may allow more species to persist.

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    • "The effects of agriculture intensification through landscape modifications on biodiversity have been widely studied those last decades (Tscharntke et al., 2005). As a result, several conceptual compromises of land management have been proposed (e.g., wildlife friendly farming vs. land sparing; (Fischer et al., 2008; Green et al., 2005) in order to conciliate crop production and biodiversity conservation. Most of these compromises give rise to important scale issues among others (Gonthier et al., 2014; Phalan et al., 2011; Quinn et al., 2012) because, to find optimal spatial scales of managing, one needs to understand at which scales biodiversity responds to environmental conditions. "
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    ABSTRACT: Following the multiplicity of studies dealing with the effects of agricultural intensification on bird diversity, one of the lessons drawn is that these effects depend on both the taxonomic group, the component of diversity, the aspect of intensification, and the spatial scale. This often leads to disparate results among studies suggesting that the investigation of agriculture-biodiversity relationships suffers from scale-dependence, information redundancy, non-linearity problems, and thus, unpredictability. Here, we propose a multi-scale and multi-facet approach to clarify the impacts of agricultural intensification on biodiversity and possible mitigating actions. Our study is based on bird and agricultural practice surveys of 199 agricultural fields in three agricultural regions of France. Using landscape characteristics and agricultural practice variables, we disentangled four main gradients of agricultural intensification on our study sites: landscape opening (farmland expansion), landscape homogenization (decrease in crop and land cover diversity), chemical intensification (fertilizer, insecticide, and fungicide), and tillage vs. herbicide. We tested whether and how these gradients interacted with each other at field, farm and regional levels in shaping taxonomic diversity (alpha, gamma and beta diversity) and ecological responses of bird communities (relative proportion of specialist vs. generalist species, trophic categories). Landscape homogenisation and opening affected the taxonomic and ecological responses of birds at field and farm levels, but not at the regional level, highlighting the scale-dependence of agriculture–biodiversity relationships. At field and farm levels, landscape opening had a positive effect on beta diversity, and community specialization by enabling the existence of farmland specialists, while heterogeneous landscapes promoted generalists. Chemical intensification had negative impacts, especially at the farm level and on almost all facets of diversity. However, some bird species seemed to tolerate higher levels of both chemical and tillage intensification. Some important interaction effects between landscape and agricultural practices, which are often disregarded, were also revealed, such that landscape homogenization in interaction with tillage reduction was correlated with higher specialization. The field level appeared mostly relevant for explaining community variations by habitat and resource availability. Meanwhile at the coarsest scale, i.e., the Small Agricultural Region, only some possible dispersal limitations were likely to occur. Finally, our results highlight the farm level (intermediate scale) as a relevant unit for management and agricultural policies, since the community responded to both landscape and agricultural practices intensification at this level. In particular, we emphasize the necessity to conserve both heterogeneous and homogeneous agricultural landscapes under extensive practices; the former promotes taxonomic diversity, when the latter favors specialized farmland biodiversity.
    Agriculture Ecosystems & Environment 01/2016; 216:9-22. DOI:10.1016/j.agee.2015.09.017 · 3.40 Impact Factor
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    • "The spatial distribution of agricultural fields is a fundamental description of rural landscapes (White & Roy, 2015) and is related to a number of ecological factors including habitat fragmentation, biodiversity , cropland species diversity (Geiger et al., 2010; Green, Cornell, Scharlemann, & Balmford, 2005; Krebs, Wilson, Bradbury, & Siriwardena, 1999), the incidence of disease pathogens and pests (Margosian, Garrett, & Hutchinson, 2009), and the regulation of agricultural nutrient, herbicide and pesticide flows (Martin, 2011). Field sizes are indicative of the degree of agricultural capital investment, mechanization and labor intensity, and information on the size of fields is needed to plan and understand these factors, and can help the allocation of agricultural resources such as water, fertilizer, herbicide, and farming equipment (Anderson, Allen, Morse, & Kustas, 2012; Johnson, 2013; Kuemmerle et al., 2013; Rudel et al., 2009). "
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    Remote Sensing of Environment 01/2016; 172:67-86. DOI:10.1016/j.rse.2015.10.034 · 6.39 Impact Factor
    • "Recent land use changes by agriculture have rapidly reduced biodiversity globally (Donald et al., 2006; Green et al., 2005; Krebs et al., 1999). To reverse the negative trend, there is an urgent need to understand crucial factors causing the decline in biodiversity and to implement appropriate conservation strategies in agricultural landscapes (Fahrig et al., 2011; Tscharntke et al., 2005). "
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    ABSTRACT: Land-use changes, including agricultural intensification and farmland abandonment, influence biodiversity in agricultural landscapes. However, few studies have focused on how the two major land-use changes affect different types of species at landscape scales. This study examined the relationships between the richness and abundance of five bird groups (agricultural wetland species, agricultural land species, grassland species, edge species, and woodland species) as well as the total species richness and abundance, and intensification or abandonment in 28 square, 100-ha grid cells in paddy-dominated landscapes in the Tone River basin of central Japan. Rice-field intensification and abandonment were not completely segregated spatially: intensification occurred in both plain and hilly areas surrounded by forests, while abandonment tended to occur in hilly areas. The effects of intensification and abandonment differed among species groups and between seasons. The richness or abundance of agricultural wetland species in summer were negatively associated with both intensification and abandonment. While the abundance of agricultural land species in winter and grassland species in both seasons were positively associated with intensification and abandonment, respectively. The total species richness and abundance did not show clear association with intensification and abandonment due to a variety of responses of the five bird groups. Based on prefectural Red Data Books, agricultural wetland species, followed by grassland species, were more threatened than other three groups in both summer and winter. This study found that (1) the diversity of habitats (including consolidated and abandoned farmlands) provides buffer areas for the different bird groups on different times of the year and (2) agricultural wetland species that use flooded rice fields in summer, such as egrets and shorebirds, are particularly threatened by both intensification and abandonment.
    Agriculture Ecosystems & Environment 12/2015; 214:21-30. DOI:10.1016/j.agee.2015.08.014 · 3.40 Impact Factor
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