Seedling and sapling banks as sources of resilience in plant communities subjected to land use change in central Argentina semiarid forests

LIPOMA MARIA LUCRECIA; DÍAZ SANDRA

Pirenópolis

Congreso; 59th Annual symposium of the International Association of Vegetation Science; 2016

International Association of Vegetation Science

Resilience is known as the capacity of an ecosystem to return to its initial state after a perturbation. One important source of resilience is the existence of reservoirs of juvenile plants belonging to the community that could establish after disturbances. Land use change is one of the main drivers of ecological change in subtropical South American forests. In this study we describe the juvenile plants bank (seedlings and saplings) of woody communities in a semiarid Chaco forest in Córdoba, central Argentina, in order to evaluate their role in the recovery of community composition. Specifically, we asked if different land use intensities had an effect on (a) total density, proportion of seedlings and saplings, richness and floristic composition of juvenile plants banks; and (b) similarity between the juvenile plants bank and the established vegetation. We selected four plant communities subjected to different past and present land use intensities: Primary Forest (PF, no land use), Secondary Forest (SF, low land use intensity), Mixed Shrubland (MS, moderate land use intensity) and Open Shrubland (OS, high land use intensity). We sampled all seedlings and saplings present in two plots of 36m2 in each plant community. We also carried out censuses of adult woody species in the same plots in order to compare floristic composition of juvenile banks and established vegetation. Density and species richness of juveniles decreased with land used intensity. Similarity in floristic composition between juvenile banks was greater between PF, SF and MS and lower between those communities and OS. Moreover, juvenile bank of SF and MS were more similar to established vegetation of PF than to establish vegetation of communities where these banks belonged. These results suggest that plant communities subjected to long-term low to moderate land use intensities have the potential to recover from the juvenile bank, but the existence of some degree of disturbances could be preventing the further establishment of individuals. In contrast, plant communities under long-term high land use intensity may have lost this source of resilience.