LB 27-276 - Dry forest restoration in Berenty Reserve, Madagascar

Background/Question/Methods:

Berenty Reserve is a research site in the south of Madagascar, dedicated to the conservation of the dry forests and its lemurs. Severe droughts have contributed to the proliferation of invasive species and a high tree mortality. Of particular concern is the lack of recruitment of the tamarind tree (Tamarindus indica), a keystone food resource for lemurs. Previous research suggested that drought hinders the growth and establishment of tamarind trees, but this hypothesis hasn’t been tested. To ensure the persistence of this unique forest and its lemurs, restoring the forest and enhancing T. indica populations is pressing. In 2017 we set up three restoration plots in the reserve to (i) to determine an optimal planting density and strategy for forest restoration projects in the tropical dry forest and (ii) to determine which are the tree species that better perform in terms of growth and regeneration. In parallel, this year we set up a greenhouse experiment at the University of Minnesota, to evaluate the effects of drought on the early regeneration of T. indica. In the experiment, we imposed a drought treatment on 200 three-month old seedlings, and monitored their growth, mortality, and physiological responses to drought stress.

Results/Conclusions:

We planted a total of 1354 seedlings of 24 species at two different planting distances (1 and 1.5m). Seedling height, canopy breadth, stem diameter, and mortality were measured for three years. We found that lower planting distance explained faster growth rates and enhanced survival in the first three years of the experiment, making planting distance an important variable to consider when planning and implementing future restoration projects in the dry forest. Our data also show which common native species thrive best. The tamarind experiment showed that watering levels but not watering frequency had a strong influence on T. indica early growth. Similarly, we found that there is an interaction between shade and watering on seed germination and seedling growth.



Results of the greenhouse experiments and of the field trials will be used to guide future restoration projects in Berenty with the intention that they can serve as a model for the restoration of other dry forests in Madagascar.