The arable plant diversity of intensively managed farmland: effects of field position and crop type at local and landscape scales

POGGIO, SANTIAGO L; CHANETON, ENRIQUE J; GHERSA, CLAUDIO M

AGRICULTURE, ECOSYSTEMS AND ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 p. 1 - 10

0167-8809

Agro-ecosystem biodiversity is threatened by increasing spatial homogenisation of intensively managedfarmland. Yet current understanding of patterns of arable plant diversity at various scales remains limited.We evaluated the extent to which species richness of arable plants in the Rolling Pampas of Argentina isdetermined by field position (fencerow, edge and centre) and crop type, at both field (local) and landscapescales. Plant richness was assessed in maize, soybean and wheat?soybean fields across four landscapetypes differing in spatial complexity, as defined by percentage area devoted to cropland. Species richnesswas hierarchically nested within landscape types, field positions and crop types. Landscape richness(-diversity, the cumulative number of species in a set of fields) was additively partitioned into twocomponents, one for local richness (˛-diversity, the mean number of species per field) and one denotingdifferences in species composition among fields (ˇ-diversity, where ˇ = −˛). Field position was the maindeterminant of landscape-scale plant richness. Overall, -diversity declined from fencerows, throughfield edges to field centres, but was unaffected by crop type. Spatial variation in species composition(ˇ-diversity), rather than species packing within fields (˛-diversity), accounted for most of the variationin arable -diversity. Higher ˇ-diversity in field edges than in field centres suggested that propaguledispersal from fencerow vegetation may create a ?mass effect? onto certain crop types. Shifts in -diversityof major perennial life-forms (chamaeophytes and phanerophytes) between field positions and crop typesreflected the contrasting disturbance regimes affecting plant communities of fencerows and cultivatedfields. Our results indicate that preserving coherent and extensive fencerow networks is essential toconserve farmland biodiversity. Moreover, maintaining landscape heterogeneity to support elevated ˇ-diversities of arable plants requires cropping systems that promote crop diversity in both space and time.