Outcomes of facilitative plant interactions in shrublands of NW Patagonia, Argentina

Abstract

Aims: This study examined the plant–plant interaction networks and analyzed to what extent different nurse species groups with different traits (evergreen and deciduous) mediate the outcomes of the facilitated species composition. Location: Four shrublands located in Nahuel Huapi National Park, in Northern Patagonia, Argentina (41°11'55.34" S, 71°19'43.07" W). Methods: We selected 10 woody species as nurse species: five evergreens and five deciduous species. We recorded species composition and total cover below nurse species and in open spaces during two consecutive years, with different interannual precipitation variability. We determined the facilitated species with the relative interaction intensity in plants (RII) index, constructed facilitation networks, and analyzed the species composition below nurses and in open spaces. Results: In our networks, nurse and facilitated species are generalist species. The species composition below the nurse canopies and open areas varied between years. The structure and parameters of networks built on two consecutive years were similar. However, we found changes in plant species interactions between the studied years. The species composition of the facilitated species growing below the deciduous and evergreen nurse species groups was similar. Conclusions: Our findings provide insights into knowledge of the facilitation networks in Patagonian shrublands. We found that networks were not nested and had many generalist species (nurses and facilitated). This implies that the disappearance of any nurse species would not change the community maintenance.