Intensive agriculture erodes β-diversity at large scales.
Biodiversity is declining from unprecedented land conversions that replace diverse, low-intensity agriculture with vast expanses under homogeneous, intensive production. Despite documented losses of species richness, consequences for β-diversity, changes in community composition between sites, are largely unknown, especially in the tropics. Using a 10-year data set on Costa Rican birds, we find that low-intensity agriculture sustained β-diversity across large scales on a par with forest. In high-intensity agriculture, low local (α) diversity inflated β-diversity as a statistical artefact. Therefore, at small spatial scales, intensive agriculture appeared to retain β-diversity. Unlike in forest or low-intensity systems, however, high-intensity agriculture also homogenised vegetation structure over large distances, thereby decoupling the fundamental ecological pattern of bird communities changing with geographical distance. This ~40% decline in species turnover indicates a significant decline in β-diversity at large spatial scales. These findings point the way towards multi-functional agricultural systems that maintain agricultural productivity while simultaneously conserving biodiversity.
Center for Conservation Biology, Department of Biology, Stanford University, Stanford, CA 94305, USA. dkarp@stanford.edu
Daniel S
DS
Karp
Andrew J
AJ
Rominger
Jim
J
Zook
Jai
J
Ranganathan
Paul R
PR
Ehrlich
Gretchen C
GC
Daily
D000383:Agriculture; D000818:Animals; D044822:Biodiversity; D001717:Birds; D003247:Conservation of Natural Resources; D003364:Costa Rica; D010944:Plants; D011157:Population Dynamics; D014197:Trees