Spatial patterns of plant species richness in relation to distance from crop field margins in the Rolling Pampa (Argentina).

POGGIO, S.L., GHERSA, C.M., CHANETON, E.J.

Bari, Italia

Congreso; 13th European Weed Research Society Symposium; 2005

European Weed Research Society

Crop field margins contribute to the maintenance of biodiversity in agro-ecosystems despite being affected by intensive management aimed at controlling weeds and agricultural pests. We sampled vascular plant species richness at increasing distances from field margins of winter (wheat and pea) and summer crops (maize and soybean) to examine spatial relationships between the margin and inner field floras. Plant richness decreased abruptly within 8 m from field margins but stabilised at greater distances in all crops. Richness did not differ between the margins of pea (23.7 ± 2.05) and wheat (21.5 ± 8.05) crop fields, but infield richness was greater (P < 0.001) in pea (20.4 ± 1.57) than in wheat (4.5 ± 0.62) fields. Thus, these winter crops differed regarding the slope of richness spatial decline and the value at which richness became stabilised with distance from the margin. Maize and soybean crops did not differ (P = 0.336) in field margin richness (soybean: 16.8 ± 1.57; maize: 18.6 ± 1.11), nor they differed (P = 0.588) in their infield plant richness (soybean: 8.5 ± 0.98; maize: 9.2 ± 0.90). Our results highlight the contribution of field margins to plant diversity in agro-ecosystems and the need for sampling stratification in large-scale floristic surveys. The observed patterns of plant richness suggest that source-sink relationships between the flora of margins and that of the interior of arable fields change with crop identity.