Assessment of the response of tropical dry forests to El Niño southern oscillation

Abstract

Tropical Dry Forests (TDFs) in the Americas are significantly affected by drought related to El Niño Southern Oscillation (ENSO). The analysis builds upon two drought indices: the MODIS-derived Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and the Sea Surface Temperature (SST) anomaly in the Niño 3.4 region. Temporal correlation analysis and Moving Window Correlation Analysis (MWCA) were used to explore the long-term and short-term responses at multiple sites. Results illustrate Gross Primary Productivity (GPP) at SRNP-EMSS (Santa Rosa National Park Environmental Monitoring Super Site) and PEMS (Parque Estadual da Mata Seca) in the dry season were negatively impacted by the long-term SST anomaly across multiple ENSO phases (warm, neutral, and cold phases), while there was no long-term impact at CCBR (Chamela-Cuixmala Biosphere Reserve) and TVMWR (Tucabaca Valley Municipal Wildlife Reserve). Findings from a short-term perspective, suggest that the GPP at SRNP-EMSS and CCBR were sensitive to the ENSO warm phase. TDFs GPP at PEMS and TVMWR were resistant to El Niño. Our results reveal that stronger El Niño events may lead to severe droughts in more regions across TDFs, but there is no direct relationship between the intensity of an individual El Niño event and the precipitation condition in each study site. Except for their teleconnections, the biophysical characteristics and seasonality can impact the response of ENSO on the GPP.