Moderate disturbances and nurse effect enhance perennial grass recruitment in northern Patagonia

LEDER, CINTIA VANESA; TORRES ROBLES, SILVIA SUSANA; PETER, GUADALUPE

JOURNAL OF ARID ENVIRONMENTS

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2021

0140-1963

Herbivory and fire promote changes in vegetation patches of arid environments, and recruitment plays a key role in its maintenance. Our aim was to study seedling dynamics in sites with different land use histories related to grazing and fire in the Monte desert in north-eastern Patagonia, Argentina. Shrub patches were selected and seven microsites along a windward/leeward transect were established. Seedling recruitment of perennial grasses (PG), shrubs, and annual species (AS) were registered on each microsite. Shrubs did not show any significant recruitment. PG recruitment was higher in sites with low-intensity disturbances, and lower in sites without disturbances or with a severe onethat either experience a severe disturbance or no disturbances. At the leeward side, PG PG seedling abundance was similar on the leeward side, and this probinges that shrubs create similar microsites for their establishment on that side whatever the surrounding disturbance. AS recruitment increased with the disturbance intensity, with the dominance of non-native species under high disturbances and native species under low ones. PG recruitment was low, especially in severely disturbed sites. To aggravate this situation, the recruitment of PG coincided with the non-native annual recruitment peak. Our findings suggest that Tthis semiarid grazing system is sustained mainly by standing grasses re-sprouting capacity. In contrast, a low-to-medium disturbance enhances PG recruitment, especially in under-canopy microsites.