The relationship between plant diversity and facilitation during tropical dry forest restoration

Restoration programs that promote the functioning of restored ecosystems are in urgent demand. Although several biodiversity and ecosystem functioning (BEF) experiments have demonstrated the importance of functional complementarity enhancing plant community performance, no BEF study has yet experimentally manipulated facilitation testing its contribution to how the complementarity effect modulates community performance.
We built a restoration experiment manipulating diversity and facilitation in a tropical semiarid forest. We planted 4704 seedlings of 16 native tree species to assemble 147 experimental communities with 45 different compositions comprising 1, 2, 4, 8 or 16 species. Facilitation was included in the experimental design by creating a gradient of communities from low to high facilitation potential (based on prior research). We measured functional diversity and functional identity using species above and below-ground traits to investigate how they modulate the effects of spec..., Methods
The work was developed at the Brazilian semiarid Caatinga, the largest and most diverse Seasonally Dry Tropical Forest of the Americas (da Silva et al., 2017). Its total area encompasses 826,411 km2, and occupies 11% of the Brazilian territory, although half of its original area has been degraded, the other half is represented by 47100 forest fragments that suffer constant anthropogenic disturbance (Antongiovanni et al., 2018; Antongiovanni et al., 2020). This study was conducted at the Açu National Forest, in the northeast of Brazil (05º34'20\"S, 36º54'33\"W), in which there is an agreement between this university, the protection area and the environmental council of Brazil. The National Forest encompasses 528 ha, where vegetation is characterised by trees varying from 2 to 15 m in height, with mean annual temperature of 24ºC and mean annual rainfall of 607mm. Plants lose their leaves during the dry season and produce new leaves at the beginning of the rainy season that extends f...,