Water use and carbon balance dynamics of cloud forest woody species

Abstract

Frequent fog events are one of the main climatic characteristics of Tropical Montane Cloud Forests (TMCF). Several studies have already shown that fog plays an important hydrological role on these ecosystems, and the decrease in the amount of fog events caused by climatic changes can be an important threat to TMCF integrity. Additionally, forest fragmentation, i.e. the conversion of forest areas into pastures and crop-plantations has reduced TMCF area in Earth's tropical belt and can potentially compromise the functioning of the remaining forest areas. We intend to investigate how changes in soil and atmospheric conditions caused by climatic variations (i.e. seasonal droughts and fog events) and forest fragmentation affect the functioning of TMCF vegetation in different spatial and temporal scales. We will use real time plant functioning monitoring techniques, such as sap flow measurements to estimate whole tree water use and automatic high-precision dendrometers to monitor carbon assimilation and allocation. These data will be combined with monthly measurements of ecophysiological parameters (leaf water potential and water use efficiency) and abiotic data (Solar radiation, rainfall, soil volumetric water content, atmospheric humidity and temperature, fog frequency, intensity and interception by the vegetation), which will be collected in real time with a network of micrometeorological sensors. All the data will be collected along a TMCF fragment adjacent to a pasture, so we will be able to understand the ecophysiological response of TMCF dominant tree species to climatic variation, land use change and the interaction between these factors. Our results should provide new insight about TMCF vegetation functioning and how these species might respond to climatic change that affects the water balance of these ecosystems. We also should provide an estimate of TMCF vegetation contribution to cloud water interception and how land-use change affects this important ecosystem service. (AU)