Resumo

POGGIO, Santiago L. Understanding weed shifts by applying the assembly rules framework. Ecol. austral [online]. 2012, vol.22, n.2, pp.150-158. ISSN 1667-782X.

Agriculture provides interesting situations to study ecological succession in weed communities. There is empirical evidence of floristic shifts in weed communities due to both environmental and technological changes, which have been interpreted in the light of succession theory. In turn, the assembly rules framework has proved to be useful to describe and predict patterns of change in communities. The aim of this paper is to present the application of an approach based on community assembly rules to study floristic changes in weed communities. Assembly rules are associated with specific factors that explain the patterns observed in a community. Assembly rules operate as a filter restricting the number of species of the regional pool that occur in local communities. The regional species pool is defined by means of a hierarchical classification as three nested spatial domains: geographic, landscape and habitat type. At large spatial scales (1000-10000 km²), the species pool is determined by the factors regulating the rates of both speciation and extinction and plant migrations between distant regions. Landscape complexity effects are higher at regional level. While dispersion increases its influence in mosaics of patches (100 m²-10 ha), habitat heterogeneity is more important in smaller patches (1-1000 m²-1 ha). In small plots (<10 m²), plant communities are modulated by biotic interactions, soil fertility, abiotic stress and microdisturbances. Species from the regional pool are fi ltering out by the limitations to dispersal within the region and the restrictions imposed by both the abiotic environment and biotic interaction at local scale. Community assembly rules provide a flexible framework for building descriptive models of successional trajectories in weed communities in response to changes in agricultural systems.

Palavras-chave : Community assembly; Dispersal; Disturbance; Species pool; Weed community dynamics.

        · resumo em Espanhol     · texto em Espanhol     · Espanhol ( pdf )