The Acaena splendens dwarf shrub promotes diversity and seedling emergence in degraded grasslands of northwestern Patagonia.
GONZALEZ S.; GHERMANDI L.
PUBLIC LIBRARY SCIENCE
Lugar: San Francisco; Año: 2019
The facilitation mechanism maintains ecosystem richness by increasing seedling recruitment. Overgrazed grasslands of northwestern Patagonia are invaded by shrubs that couldpromote the seedling recruitment of forage species. We investigated the role of Acaenasplendens shrubs on the maintenance of diversity and its usefulness as a nurse shrub in therecruitment of Festuca pallescens, a grass of high forage value present with a low cover indegraded grasslands. To test the performance of A.splendens as a nurse plant in nondegraded grassland, we recorded the species richness four years inside of A. splendenssenescent shrubs and in gaps among dominant tussock grasses. Species were grouped infour functional groups: annual and biannual herbs and grasses, perennial herbs, perennialgrasses and shrubs. To test the usefulness of A. splendens in the restoration of degradedgrassland, we monitored the seedling emergence and survival of F. pallescens inside A.splendens and in gaps. We related seedling survival to meteorological and microenvironmental conditions. Species richness was higher in Acaena nurse plants than in gaps. Thefrequency of functional groups, with exception of annual and biannual herbs and grasses,were higher in Acaena than in gaps. Seedling emergence and survival of F. pallescens werehigher in Acaena, but the seedlings died in summer in both microsites. Mean maximum temperature was higher and mean minimum humidity lower in gaps than in Acaena duringspring. However, the spring-summer season in which we monitored F. pallescens survival,was exceptionally dry and hot, affecting the survival of F. pallescens seedlings. Our resultsshow that A. splendens act as a nurse species increasing the richness in the non-degradedgrassland and facilitating the seedling recruitment of an important forage species in thedegraded grassland. Nevertheless, the facilitation mechanism will fail in drought conditions,indicating that this restoration tool is limited by climate.