The relationship of bird diversity to crop and non-crop heterogeneity in agricultural landscapes

• Habitat heterogeneity is often assumed to benefit farmland biodiversity. Increasing heterogeneity of non-crop habitats is often too costly in terms of agricultural production. It has been suggested that increased crop heterogeneity could mitigate the negative effects of intensification on biodiversity while still maintaining high production levels.We investigated if habitat-specific species pools of two groups of farmland birds, field-nesting and non-crop-nesting species, were related to landscape-level heterogeneity of crop and non-crop cover. We analysed total number of species (gamma diversity) and average local species richness (alpha diversity) in landscapes and related these two biodiversity measures to four components of landscape heterogeneity (compositional and configurational heterogeneity of crop and non-crop cover).We selected 30 farmland landscapes (each 25 km(2)) in Sweden that largely broke up correlated relationships between crop and non-crop heterogeneity and between compositional and configurational heterogeneity. Estimates of species richness (alpha and gamma diversity) were calculated with bird survey data from specific habitats within landscapes (farmsteads and arable fields) and then related to measures of landscape heterogeneity.No measure of landscape species richness was associated with landscape-scale crop cover heterogeneities. However, gamma diversity of both bird groups was negatively related to the compositional and configurational heterogeneity of non-crop land-use in the landscapes, respectively.Our results suggest that: (i) crop heterogeneities are not related to habitat-specific richness of farmland birds, (ii) heterogeneity effects of habitat complementarity in general are weak and (iii) relationships between diversity and heterogeneity in landscapes are dependent on the biodiversity measure used.

Subject headings

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Publication and Content Type

ref (subject category)

art (subject category)