Dinâmica temporal da velocidade do fluxo de seiva de indivíduos arbóreos em resposta a fatores ambientais e morfoanatômicos na Amazônia Central

Abstract

The sap flow velocity, in addition to being considered an important parameter for the estimates of transpiration rate by the plant, it is also an important proxy for understanding ecological processes in forest ecosystems. Several environmental factors and functional traits can influence water use patterns. In heterogeneous environments with a rich diversity of species and functional attributes, such as tropical forests, the factors that drive the temporal dynamics of sap velocity are still not well understood. Therefore, the aim of this study is to investigate how environmental and morphoanatomical factors influence the temporal dynamics of the sap flow velocity of arboreal individuals in a terra firme forest in Central Amazon. The study was conducted at the Tropical Silviculture Experimental Station - ZF-2. We selected nine individuals of nine specie located in a plateau area and with different diameters, heights and phytosociological positions. The individuals were monitored with sap flow sensors between February and September 2019. We measured the environmental variables (air temperature and relative humidity, vapor pressure deficit, direct solar radiation and soil moisture) and variables related to functional traits (sap flow velocity, leaf area, specific leaf area, quantitative anatomy of the leaf epidermis, quantitative anatomy and branch xylem density). We identify that influence of the main factors que directs the velocity of sap vary in response to changing seasonality, the solar radiation is the key environmental factor in the wet period and VPD to the dry period. We also identify that the individuals presented different patterns of sap flow velocity, these patterns are related to some functional traits in response to the period, evidencing the characteristics of light capture (specific leaf area) and hydraulic architecture and efficiency (tree height, frequency of vessels and stomatal density) for the wet and dry periods, respectively. We concluded that the contribution of different functional traits to the greater efficiency in the use of water resources by tree is regulated by environmental pressures in response to seasonal changes.