Identifying success factors for the recovery of Andean tropical forests using observational and experimental plots

The Andean tropical forests (ATF) are a well-known biodiversity hotspot, and they provide numerous ecosystem services such as carbon storage and water regulation. However, human activities including establishing pastures, cultivating crops, and fires, have significantly reduced the area covered by tropical forests and altered their structure, composition, and function. To counter forest degradation, various active restoration programs have been conducted. However, there is limited understanding regarding what factors influence the success of Andean forest recovery. Using a network of observational and experimental plots, that allow an understanding of recovery pathways across time and over environmental conditions, we address the question: what are the driving factors influencing establishment success in reforestation efforts? We established 118 observational plots along different environmental conditions (e.g. climate and soil types), and 96 experimental plots across an elevation gradient in Ecuador. The observational plots were established in 18 different young reforested sites (5 -10 years) to assess carbon productivity. On the other hand, the experimental plots were installed at three elevations (2200, 2800, and 3200 m a.s.l.) to evaluate the effects of pasture competition and artificial shading, in a factorial design, on survival and growth rate of five native tree species. Our findings from the observational plots revealed that grazing exclusion, precipitation, planted species richness, and soil properties significantly influence carbon productivity in reforested sites. Preliminary results from the experimental plots revealed that the effect of grass competition and shade on seedling performance varied tremendously according to species and elevation. In summary, our results suggest that land management practices, planted species richness and species type, and climate conditions are determining factors in regard to successful forest recovery.