Variáveis climáticas e hidrológicas regem o incremento diamétrico anual e a regulação hidráulica da espécie Hydrochorea corymbosa (Fabaceae) em uma floresta de várzea na Amazônia Central

Abstract

The Amazon region have been strongly impacted by the intensification of the hydrologic cycle during recent decades leading to an increase in the magnitude and frequency of extreme flood and drought events in the rivers. Severe floods increase the duration of the aquatic phase in floodplains forests affecting tree physiology and growth in these environments. Studying responses of trees to environmental variations are essential to understand the trees vulnerability in the Amazonian floodplain forests under climate change scenarios. This study was performed in nutrient-rich Central Amazonia floodplain forests (várzea), located at Catalão Lake of the municipality Iranduba, Amazonas state. A total of 30 individuals with diameter at breast height (DBH) ≥20,0 cm of the tree species Hydrochorea corymbosa (Fabaceae) were studied, growing at topographic elevations with differences of up to meters. From each tree two wood samples were collected using a mechanized borer with internal diameter of 12 mm at a mean height of 0.95 m above the soil. Applying cross-dating techniques a tree-ring chronology was developed. Annual sapwood area was estimated and anatomic parameters (vessel area, vessel frequency and parenchyma quantity) of the growth rings were measured and extrapolated to the active sapwood area along a chronosequence. Time series of tree rings and wood parameters were related to hydrologic variables (duration of aquatic and terrestrial phases, flood height and groundwater depth), regional (monthly values of precipitation, maximum temperature, minimum temperature and evapotranspiration) and global climate parameters (monthly sea surface temperature (SST) anomalies of North Atlantic OceanNATL, South AtlanticSATL and the Atlantic Meridional ModeAMM). The tree-ring chronology covered the period of 1978-2019, but didn´t show any correlation with regional hydro-climatic variables. Significant correlation was only observed with SST anomalies of the NATL that has strong influence on pluviometric and hydrologic regimes of Central Amazonia. The sapwood area (cm²), active vessel area (cm²) and lost vessel area (cm²) are correlated with air temperature, evapotranspiration and SST-NATL, while vessel diameter, vessel frequency and quantity of parenchyma are adjusted by the hydrological regime (flood height, duration of aquatic and terrestrial phases). The species showed great anatomic plasticity resulting to interannual adjustments which allows the species to adapt to environmental changes.