Do nurse plants and cattle exclusion help restore Parlatore’s Podocarp forest?

Abstract

In the Neotropical cloud forests of northwest Argentina, cattle ranching has been historically the primary economic activity, with potential negative impacts on the ecosystem. Understanding factors influencing tree regeneration is crucial for reforestation efforts in grazed areas. Given the limited understanding of Parlatore's Podocarp (Podocarpus parlatorei Pilg.) regeneration ecology, a unique gymnosperm species in the Southern Yungas' Montane Forest, we evaluated the growth and survival of its saplings for one year after planting them both inside and outside an exclosure, and in association with or without unpalatable nurse plants. Inside the exclosure, sapling survival was 100%, regardless of nurse plants. However, outside the exclosure saplings associated with nurse plants had 19.5 times higher survival probability. Growth rates were higher inside the exclosure and for saplings associated with nurse plants. The positive effect of nurse plants on growth was similar inside and outside the exclosure. Cattle browsing and trampling on Parlatore's Podocarp were observed for the first time, highlighting a previously undocumented threat to the species. Our findings offer valuable insights for ecological restoration, potentially suggesting strategic sapling planting near unpalatable plants and considering cattle exclusion in key areas to enhance long-term restoration success in the Southern Yungas' Montane Forest.