Integration of RS and GIS to Assess Human Impact on Ecosystem Change in Llanos Area (Venezuela)
1Yanning Guan (China), 2Steven M. de Jong, 3Johan de Meijere (Netherlands)
1Institute of Remote Sensing Applications, Chinese Academy of Sciences,
P. Box 9718, Beijing 100101, China
Tel: 86-10-64889540
E-mail: gyn@hrs1.irsa.ac.cn
2Center of Geoimformation, Wageningen University and Research Center
3International Institute for Aerospace Survey and Earth Sciences
Keywords:
landscape ecology, ecosystem change, human impact, probability model, flooding savanna, integration of RS and GIS.
Abstract:
Landscape ecology emphasizes large areas and ecological effects of the spatial patterning of ecosystem. Recent developments in landscape ecology have emphasized the important relationship between spatial patterns and many ecological processes. Quantitative methods in landscape ecology link spatial patterns and ecological processes at broad spatial and temporal scales. In turn the increased attention on temporal change of ecosystem and human impact has highlighted the need for quantitative methods that can analyze patterns, determine the importance of spatially explicit processes, and develop reliable model. This research applies quantitative methods to assess the human impact on ecosystem temporal change in the flooding savanna area. Remote sensing offers the temporal change of ecosystem on landscape characteristics and disturbed by human. GIS as an important tool use in ecosystem temporal change analysis, landscape fragmentation analysis, and a probability model was developed to assess the relationship between ecosystem change and anthropogenic variables. The results are calculated in different scales.
1. Introduction
Landscape processes are dynamic and various climatic, lithological, landscape and anthropological factors contribute to significant spatial and temporal variability in environmental phenomena. Recognition, interpretation and mapping of the variability of process controlling variables and land conditions are imperative for assessing impact on ecological environment of human being and implementation of effective natural resources management.
Remote sensing image analyses systems and Geographic Information System (GIS) show great functionality for the integration of a wide variety of spatial information supporting tasks such as natural resource management, regional planning, and environmental monitoring. Current remote sensing programs are based on a variety of sensors that provide temporal and spatial earth observation on a global scale, thereby offering the opportunity for analyses of various phenomena synoptically from local to global scales. These attributes make remote sensing appealing for application to landscape ecology. GIS offers efficient tools for handling, manipulating, analyzing and presenting spatial data. Working in an integrated remote sensing and GIS environment allows taking advantage of both GIS and remote sensing image analysis techniques.
Remote sensing and GIS are powerful tools for the integration of a wide variety of spatial information applying tasks such as natural resource management and environmental change monitoring. Remote sensing technology and GIS offer the ability to facilitate ecosystem change investigations leading to a more complete understanding of human impact on the ecosystem. The research gives the approaches to derived the ecosystem temporal change and landscape fragmentation analysis by integrated remote sensing and GIS, and to model the human impact on the ecosystem change.
2. The Study Area
The flooding savannas of the Llanos area, which cover around 16,000 km
2, are in the west central part of Venezuela, and occupy portions of Guarico, Cojedes, Portuguesa, Barinas and Apure States. The study area is in the Apure and locates in the central of Llanos.
In 1967, there was a serious flooding in Apure, where about 50,000 km
2 were inundated. The government carried out a project named "Modulos of Apure" to control flooding and improve the hydrologic management of the region. There are 188, 000 ha of modulated area constructed. The advantages of the project were evident when productivity indexes of the modulated savannas under rational management were compared against the indexes of the natural savanna under traditional management. A series of dikes have been built for experiment. The dikes are more or less perpendicular to the riverbanks, and parallel to each other. The area closed by these dikes and riverbanks is called a 'module'. A module can be defined as: "a sector of savanna that has been provided with low earth dikes to retain rainfall water in order to maintain green pastures throughout the year. These dikes have also the additional use as communication ways (roads)" (Gisele, 1998).
The construction of dikes has had an enormous effect on the economy of the Apure area. It not only impacts the local economy situation, but also affects the ecosystem in numerous ways. Change in hydrological factors, such as increased or decreased spate frequency and magnitude, change in frequency of drying events or shortening of drying, can affect the ecosystems extremely. The faunas characterised by extraordinarily rapid development. Similarly, biotic communities of the module area are disturbed. The stability of the habitats in these disturbed ecosystems may, in some case, provide a refuge for many species on other hand the construction of dikes led to an increase in influences on ecosystem by human being.
