Crop Species Diversity Changes in the United States: 1978-2012

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Show simple item record Aguilar, Jonathan P. Gramig, G. G. Hendrickson, J. R. Archer, D. W. Forcella, F. Liebig, M. A. 2016-04-20T22:11:10Z 2016-04-20T22:11:10Z
dc.description Citation: Aguilar, J., Gramig, G. G., Hendrickson, J. R., Archer, D. W., Forcella, F., & Liebig, M. A. (2015). Crop Species Diversity Changes in the United States: 1978-2012. Plos One, 10(8), 14. doi:10.1371/journal.pone.0136580
dc.description.abstract Anecdotal accounts regarding reduced US cropping system diversity have raised concerns about negative impacts of increasingly homogeneous cropping systems. However, formal analyses to document such changes are lacking. Using US Agriculture Census data, which are collected every five years, we quantified crop species diversity from 1978 to 2012, for the contiguous US on a county level basis. We used Shannon diversity indices expressed as effective number of crop species (ENCS) to quantify crop diversity. We then evaluated changes in county-level crop diversity both nationally and for each of the eight Farm Resource Regions developed by the National Agriculture Statistics Service. During the 34 years we considered in our analyses, both national and regional ENCS changed. Nationally, crop diversity was lower in 2012 than in 1978. However, our analyses also revealed interesting trends between and within different Resource Regions. Overall, the Heartland Resource Region had the lowest crop diversity whereas the Fruitful Rim and Northern Crescent had the highest. In contrast to the other Resource Regions, the Mississippi Portal had significantly higher crop diversity in 2012 than in 1978. Also, within regions there were differences between counties in crop diversity. Spatial autocorrelation revealed clustering of low and high ENCS and this trend became stronger over time. These results show that, nationally counties have been clustering into areas of either low diversity or high diversity. Moreover, a significant trend of more counties shifting to lower rather than to higher crop diversity was detected. The clustering and shifting demonstrates a trend toward crop diversity loss and attendant homogenization of agricultural production systems, which could have far-reaching consequences for provision of ecosystem system services associated with agricultural systems as well as food system sustainability.
dc.rights CC0 1.0 Universal (CC0 1.0)
dc.subject Integrated Agricultural Systems
dc.subject Genetic Diversity
dc.subject Biodiversity
dc.subject Landscape
dc.subject Management
dc.subject Diversification
dc.title Crop Species Diversity Changes in the United States: 1978-2012
dc.type Article 2015
dc.citation.doi 10.1371/journal.pone.0136580
dc.citation.issn 1932-6203
dc.citation.issue 8
dc.citation.jtitle PLoS One
dc.citation.spage 14
dc.citation.volume 10
dc.contributor.authoreid jaguilar

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