Research Statement

Land Cover Effects on Water Fluxes and Atmospheric Deposition across a Mexican Tropical Montane Landscape

Tropical montane cloud forest landscapes experience frequent fogs and high deforestation rates. Fog deposition, a significant hydrological and chemical input in cloud forest regions, is partially controlled by vegetation receptor surfaces. Forest conversion may thus have direct effects on the volume, distribution, and chemistry of fog inputs, as well as indirect effects on plant population and ecosystem dynamics. Moreover, the types and intensities of land use practices will determine the magnitude of these effects. This study will compare and contrast rain and fog water fluxes and deposition within cloud forest fragments, shade coffee plantations, and cattle pastures in eastern Mexico. Fog interception is influenced by fog frequency, leaf, stand, and landscape scale properties, hence a multi-scaled investigation will be employed. The net throughfall flux method will be used to estimate rates of fog capture and of NO3-, SO42-, and Cl- deposition. In addition, potential drivers of these processes, including leaf traits, stand structure, presence of edges, and land cover area will be measured. A major objective of the study is to investigate which independent variables are most important in controlling throughfall fluxes, and on which spatio-temporal scales. At the forest patch level, water and nutrient fluxes are predicted to differ across an edge-to-interior gradient. A seedling experiment will test the effects of edge-related changes in fog water fluxes on seedling growth and survivorship rates. At the ecosystem level, species’ leaf traits, capturing surface area, and the structural complexity of land cover types are predicted to differ along a continuum from grassland to forest and strongly influence fog deposition. A model will be developed to predict rates of NO3-, SO42-, and Cl- deposition as a function of current and future scenarios of land cover type in the Xalapa-Coatepec region. Fog deposition will be calculated by multiplying measured fog water volumes in throughfall by sampled chemical concentrations in fog water collected in open areas. A mean deposition rate for each land cover type will be computed, and a model will be used to extrapolate deposition rates to the landscape (i.e., mean deposition rate for each land cover type x area occupied by land cover type). The proposed research will provide valuable information on the capture potential of and deposition rates within remnant forests, forested agroecosystems, and pastures. The study will thus inform policy makers of the ecosystem goods and services provided by three land cover types, ubiquitous in the human-inhabited landscapes of mid-elevation Latin America. Further, experimental work may elucidate possible feedback loops between fragmentation, fog interception, and seedling regeneration.

Topics

• Forestry, Forest Science and Management
• Region: Latin America and the Caribbean
• Atmospheric Science