Does diversity beget diversity? The influence of variation in nucleation techniques on species and functional composition in early Atlantic Forest restoration

Abstract

Restoring ecosystems to mitigate the effects of environmental degradation is an urgent challenge, particularly in areas where biodiversity loss and the decline of natural habitats are accelerating. Among the mechanisms for ecosystem restoration, nucleation techniques stand out as strategies aimed at restoring degraded areas by creating vegetation nuclei, patches of vegetation that serve as focal points for the natural regeneration of other plant species. This thesis is organized into two chapters to examine the spatial and methodological patterns of nucleation techniques in the Neotropics and evaluate their field effectiveness in the Atlantic Forest. The first chapter provides a systematic review of scientific articles that have nucleation techniques in Neotropics terrestrial ecosystems. From the review of 58 studies, we identified 12 techniques, with artificial perches, topsoil transfer, seedling islets, and brushwood being the most frequent. Spatial and methodological patterns varied depending on the stakeholders involved (researchers, private sector, and government agencies) and the landuse history. Researchers frequently applied combined techniques, whereas the use of isolated techniques prevailed among other stakeholders. Greater diversity of techniques was observed in abandoned pastures, mining areas, and protected areas. Advancing the use of combined techniques and standardizing practices is crucial for enhancing the effectiveness of nucleation in ecological restoration. The second chapter focuses on a field experiment evaluating species and functional diversity using nucleation techniques applied to an abandoned pasture in the Atlantic Forest. Nine nucleation techniques were tested, following a gradient of diversity, with treatments including one technique, three techniques from the same group, three techniques from different groups (one from each group), and nine techniques (maximum diversity). After 15 months, we found that nucleation significantly increased species diversity and ecological functionality, with techniques involving seed inputs, such as seed nests and topsoil transfer, showing the highest plant recruitment. Combining techniques promoted greater species diversity, although functional diversity did not yet follow the same pattern. We identified key species capable of overcoming environmental filters in the degraded area, with potential for use in restoration projects in contexts with similar land-use histories. These findings highlight the potential of nucleation as an efficient and scalable strategy for restoring degraded landscapes.