A framework for integrating environmental modeling towards enhancing bundled environmental services: An example from an Andean watershed.

摘要

There is an increasing interest in environmental benefits provided by ecosystems. Among the wide range of environmental services, hydrological services are important not only because they affect all sectors of human behavior, but because they are closely tied to other services such as food supply and carbon sequestration. Investments in watershed management and the development of new market incentives are of increasing importance in both temperate and tropical regions. One of the mechanisms that have been strongly promoted is the adoption of Payment for Environmental Services (PES). In Latin America, most PES programs have been designed by estimating the provision of services using conventional knowledge about the direction and magnitude of the linkages between land use and hydrological variables. However, more often than not, we do not actually have measurements and data about the relationship between land use and the provision of many environmental services. Therefore, there is an increasing demand for estimating environmental services tradeoffs emerging from land use changes in order to enhance the bundle of ecosystem services available from a watershed, as well as methods to quantitatively evaluate these linkages.;This thesis presents a conceptual framework for evaluating ecosystem functions and the application of an environmental index that combines environmental assessments and economic valuation. Three environmental services were evaluated: erosion control, discharge regulation and carbon sequestration. The 258 km 2 of Las Ceibas watershed served as a case study, which is an agricultural basin located in Colombia, South America. Runoff and sediment processes were analyzed using the Soil and Water Assessment Tool (SWAT), and carbon sequestration potential using the CO2FIX model. I simulated three scenarios: (1) rotational grazing, (2) green manures and cover crops and (3) reforestation. The results indicate that reforestation, which mainly targeted the increase of carbon sequestration, also improved the provisioning of hydrological services through improvements in erosion control and discharge regulation. Synergies were found between environmental services in the three conservation-oriented scenarios analyzed. Tradeoffs were found between annualized profits from agricultural activities with sediment control, and annualized profits from agricultural activities with carbon sequestration. Environmental modeling proved to be a useful tool in making the synergies in bundled environmental services evident; furthermore it suggested alternatives for the most feasible management practice.