Where does the forest come back from? Soil and litter seed banks and the juvenile bank as sources of vegetation resilience in a semiarid Neotropical forest

Abstract

The existence of reservoirs from which dominant plants recruit after disturbances is a key factor in ecosystem resilience. Where do woody species regenerate from in the semiarid Neotropical Chaco forest? Is land use affecting the floristic composition of biodiversity reservoirs? Are the soil and litter seed banks and the juvenile bank potential sources of resilience of these forests in the face of different land‐use regimes? Chancaní, Northwestern Córdoba, Argentina. We selected four ecosystem types subjected to increasing long‐term land use intensity: primary forest (no land use in the last 50yr), secondary forest (low land use intensity), closed species‐rich shrubland (moderate land use intensity), and open shrubland (high land use intensity). We monitored four sites per ecosystem type where we recorded adults, saplings and seedlings of all woody species. We collected litter and soil samples that were processed in the laboratory for taxonomic identification and germination of seeds. We compared the floristic composition of the soil and litter banks, as well as juvenile bank (?biodiversity reservoirs?) with that of established vegetation of the primary forest, considered as the reference ecosystem. We also compared the established vegetation from sites under land use with that of the primary forest. Woody species were scarcely represented in the soil, but very well represented in the litter and the juvenile banks from different ecosystem types. These two reservoirs showed high similarity with the established vegetation of the primary forest. However, as land use intensity increased, similarity between the reservoirs and the established vegetation of the primary forest decreased. Litter and juvenile banks, but not the soil bank, are the main reservoirs for the recruitment of new individuals of woody species in the Chaco forest. However, the ability of these reservoirs to act as sources of resilience decreases as land use intensifies.