Woody Species Richness and Precipitation as drivers of Primary Productivity in Dry Forests of Northeastern Brazil

Abstract

Although it is common sense in the scientific community that there is a correlation between species richness and primary productivity, empirically this is poorly addressed for semiarid ecosystems. In the present study (1) we correlate woody species richnesswith a vegetation index from satellite data (as a proxy for primary productivity); we also determined (2)  the effect of rainfall on productivity,  and (3) rainfall and productivity anomaly indices for 49 sites in Dry Forests of Northeastern semiarid region of Brazil. We show that both species richness and rainfall are positively correlated  with  productivity (r² = 0,33 and p < 0,05;r² = 0,11, n = 49 and p < 0,05,  n = 49; respectively). Productivity has a significant one month lag in response to rainfall (r2 = 0.39 ± 0.16; p < 0.001; n = 49). We also found that rainfall shows an anomaly 3 times more intense than the productivity anomaly (p < 0.001, r2 = 0.5). We conclude that at the regional level, woody species richness has a stronger effect than rainfall on productivity of Dry Forests of semiarid Brazil. In addition, the anomaly results showed the vegetation´s resistance to the semiarid harsh climate, an important result for conservation and policy under a climate change scenario.