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

LIPOMA, ML; DÍAZ, S

Pirenópolis

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

Resilience is known as the capacity of an ecosystem to return to its initial stateafter a perturbation. One important source of resilience is the existence ofreservoirs of juvenile plants belonging to the community that could establishafter disturbances. Land use change is one of the main drivers of ecologicalchange in subtropical South American forests. In this study we describe thejuvenile plants bank (seedlings and saplings) of woody communities in asemiarid Chaco forest in Córdoba, central Argentina, in order to evaluate theirrole in the recovery of community composition. Specifically, we asked if differentland use intensities had an effect on (a) total density, proportion of seedlingsand saplings, richness and floristic composition of juvenile plants banks; and (b)similarity between the juvenile plants bank and the established vegetation. Weselected four plant communities subjected to different past and present land useintensities: Primary Forest (PF, no land use), Secondary Forest (SF, low landuse intensity), Mixed Shrubland (MS, moderate land use intensity) and OpenShrubland (OS, high land use intensity). We sampled all seedlings and saplingspresent in two plots of 36m2 in each plant community. We also carried outcensuses of adult woody species in the same plots in order to compare floristiccomposition of juvenile banks and established vegetation. Density and speciesrichness of juveniles decreased with land used intensity. Similarity in floristiccomposition between juvenile banks was greater between PF, SF and MS andlower between those communities and OS. Moreover, juvenile bank of SF andMS were more similar to established vegetation of PF than to establishvegetation of communities where these banks belonged. These results suggestthat plant communities subjected to long-term low to moderate land useintensities have the potential to recover from the juvenile bank, but theexistence of some degree of disturbances could be preventing the furtherestablishment of individuals. In contrast, plant communities under long-term high land use intensity may have lost this source of resilience.