The scale dependency of spatial crop species diversity and its relation to temporal diversity.

Autor:	Aramburu Merlos F; Department of Environmental Science and Policy, University of California, Davis, CA 95616; faramburumerlos@ucdavis.edu.; Instituto Nacional de Tecnología Agropecuaria, Unidad Integrada Balcarce, 7620 Balcarce, Buenos Aires, Argentina., Hijmans RJ; Department of Environmental Science and Policy, University of California, Davis, CA 95616.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2020 Oct 20; Vol. 117 (42), pp. 26176-26182. Date of Electronic Publication: 2020 Oct 05.
DOI:	10.1073/pnas.2011702117
Abstrakt:	Increasing crop species diversity can enhance agricultural sustainability, but the scale dependency of the processes that shape diversity and of the effects of diversity on agroecosystems is insufficiently understood. We used 30 m spatial resolution crop classification data for the conterminous United States to analyze spatial and temporal crop species diversity and their relationship. We found that the US average temporal (crop rotation) diversity is 2.1 effective number of species and that a crop's average temporal diversity is lowest for common crops. Spatial diversity monotonically increases with the size of the unit of observation, and it is most strongly associated with temporal diversity when measured for areas of 100 to 400 ha, which is the typical US farm size. The association between diversity in space and time weakens as data are aggregated over larger areas because of the increasing diversity among farms, but at intermediate aggregation levels (counties) it is possible to estimate temporal diversity and farm-scale spatial diversity from aggregated spatial crop diversity data if the effect of beta diversity is considered. For larger areas, the diversity among farms is usually much greater than the diversity within them, and this needs to be considered when analyzing large-area crop diversity data. US agriculture is dominated by a few major annual crops (maize, soybean, wheat) that are mostly grown on fields with a very low temporal diversity. To increase crop species diversity, currently minor crops would have to increase in area at the expense of these major crops. Competing Interests: The authors declare no competing interest.
Databáze:	MEDLINE
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