Weed diversity loss due to farmland homogenization

POGGIO, SANTIAGO L.; GHERSA, CLAUDIO M

Vancouver, Canadá

Congreso; 5th International Weed Science Congress; 2008

International Weed Science Society

Farmland biodiversity has declined as agriculture intensification increased in the last decades. Consequently, homogenous rural landscapes would sustain lower plant diversity than more complex landscapes comprising different types of habitats. Therefore, we tested the hypothesis that weed species diversity and annual crop percent of farmland are negatively associated at both field and landscape scales. Plant diversity was sampled in fields cropped with cool- (wheat and pea) and warm-season crops (maize and soybean). Surveys were carried out in fencerows, edges, and centres of fields. Percent of cropland in the landscape (Acropland) was chosen as a straightforward indicator of heterogeneity. Species diversity was additively partitioned into its α-, β-, and g-diversity components, calculating b-diversity as the difference between g-diversity and mean a-diversity. Then, the relationships between either a-, b-, and g-diversity and Acropland were studied. Plant diversity decreased in most field habitats as Acropland increased, but there were no significant decline for fencerow a-diversity. Fencerows sustain the highest plant diversity, despite of their low areal proportion in both landscapes and fields. Although field edge weeds are intensely controlled, field edge diversity was higher than that of field centres, which suggests that mass effects from fencerows may be involved in sustaining the weed richness of field edges. Maintaining non-cropped habitats in farmland, such as fencerows, may promote diverse arable plant communities by providing suitable habitats for both common and rare species and promoting spatial mass effects, which in turn preserve both wildlife habitats and ecological services in agro-ecosystems.