Negative responses of two dry‐adapted amphibians to tree planting density in the Great Green Wall in Senegal

Dryland restoration is a challenging task due to the intrinsic low resilience and vulnerability to land degradation of these ecosystems. Restoring vegetation communities is often the first step to reinstating ecosystem health; however, resorting to activities such as tree planting is increasingly called into question, as it may lead to abrupt habitat changes, with unpredictable effects on faunal communities. The African Great Green Wall (GGW) is a large-scale restoration initiative whose ultimate goal is improving the resilience of local communities and ecosystems. GGW interventions in Senegal include a variety of restoration activities, including reforestation. We conducted repeated count surveys of two ground-dwelling, arid-adapted amphibians (Tomopterna milletihorsini and Sclerophrys pentoni) across eight reforestation plots located along the GGW in northern Senegal and used N-mixture models to test the hypothesis that increased woody plant density due to restoration activities has negative effects on their abundances. Our results showed that woody plant density within the reforestation plots was significantly higher than their surroundings and was negatively related to amphibian abundances. Furthermore, the effect size of woody plant density differed between species, with the best model predictions showing a decrease within the reforestation plots of 74 and 29.8% in the abundances of T. milletihorsini and S. pentoni, respectively. Our study shows that woody plant density represents an important niche axis for Sahelian amphibians and that the diverse species-specific responses to tree planting activities should be taken into account when developing management plans.