Quantification of functional hydro-biogeochemical indicators in Ecuadorian ecosystems and their reaction on global change

点击翻译按钮获取中文摘要

Water is an intrinsic component of ecosystems acting as a key agent of lateral transport for particulate and dissolved nutrients, forcing energy transfers, triggering erosion, and driving biodiversity patterns. Given the drastic impact of land use and climate change on any of these components and the vulnerability of Ecuadorian ecosystems, indicators are required that describe the structural condition, capture the functional relations of and processes within those ecosystems. As part of this project extension we seek to complete the development of a set of functional indicators from the fields of hydrology and biogeochemistry customized for the selected environments. The investigated indicators describe (1) flow regime and timing, (2) nutrient cycling and flux rates, and (3) sediment fluxes.For assessing flow regime and timing we concentrated on studying stable water isotopes to estimate mean transit time distributions, that are likely to be impacted by changes in rainfall patterns and land use. Hysteresis loops and frequency analysis of nitrate concentrations have been identified as suitable functional indicators to monitor nutrient fluxes. They are most likely to be altered by changes in temperature as well as by land use and management. Finally, measured sediment fluxes indicate surface runoff contribution to total discharge, mainly influenced by the intensity of rainfall as well as land use.In the current project phase two hydro-biogeochemical monitoring networks (Páramo and tropical mountain rainforest) were established and are maintained in close cooperation with our Ecuadorian counterparts. Those networks supply the data for testing the selected indicators. For (1) we select weekly stable water isotopes samples in stream, soil and precipitation water, while for (2) and (3) we automatically record the sediment and nitrate concentrations in a high temporal-resolution.As part of this project extension, we will complete the development of the proposed functional indicators and conduct a model-based evaluation of the selected indicators under global change. The developed global change scenarios together with a tailored model setup combining the hydrological model CMF and a bio-geochemical model accounting for nutrient and carbon fluxes, will then be analyzed to capture the likely reaction of functional indicators. Finally, together with our university and non-university partners we will contribute to the written guidelines for developing a comprehensive monitoring program for biodiversity and ecosystem functions.