Evaluation of Vegetation Patch Connectivity Using Remote Sensing and Gis

The UN Conference on Environment and Development (UNCED) Agenda 21 issue for sustainable development emphasizes on an integrated approach for the maintenance and management of land resources. Conservation of biodiversity has become an important environmental issue after the UNCED. Habitat fragmentation caused by the sprawl of urban development is becoming one of the major environmental problems in the Metropolitan suburbs in Japan. The conservation of vegetation areas from urban development as well as creating more such areas has become an essential thought for today for preserving the biodiversity since vegetation area is the remaining habitat for wild-animals and wild-plants. In landscape ecological point of view, the size and distribution pattern of the vegetation patches that has become wildlife habitat and especially the strength of connectivity between such patches are important factors. Study of connectivity was preformed for remaining vegetation patches and their network within central Tokyo region. This research was carried out by applying the techniques of remote sensing to extract the vegetation patches for the study area where as evaluation of the network connectivity was done using GIS. The ranking map for the vegetation patch was generated by considering the relationship between vegetation patches and number of networks. The condition of the vegetation distribution was established based on source and sink habitat in landscape ecology. The quantitative analysis for vegetation distribution patches became possible due to generated networks of the extracted vegetation patches from the satellite data. Mochizuki, Kan-ichiro International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Supplement B7. Amsterdam 2000. 147 1 INTRODUNCTION The importance of biodiversity conservation was highly recognized after the UN Conference on Environment and Development (UNCED) in June 1992. In Japan, the environmental impact assessment law has come into force in June 1999 and a new framework was adopted considering the ecosystem and attention for the environmental protection has become paid to wildlife. It was realized to care about the ecosystem and dependency of wildlife on the nature, and to understand the importance of man-made developments for wildlife conservation. The concept of landscape ecology considers landscape elements as “patch”, “corridor” and “matrix”. In landscape ecological point of view, the size and distribution pattern of the vegetation patches that has become wildlife habitat and especially the strength of connectivity between such patches are important factors. In order to preserve the biodiversity, the conservation of vegetation areas has become essential thought in the present days. Therefore, a thorough knowledge of land cover condition, specially on vegetation covered areas, is a crucial factor. Further, a methodology to evaluate habitat depending on the movement of wildlife and vegetation distribution has become necessary. In landscape ecology, two types of patches can be recognized: a source habitat that is more dispersed than immigration of individuals; a sink habitat that has immigrated exceeding dispersal (Forman & Godron,1986 ; Forman,1995). The connectivity of habitats is crucial for the migration of wild-animals between habitats. It is important to emphasize the relationship of the connectivity between habitats rather than considering only large area. The main objectives of the present study are to examine the distribution of the wildlife habitats in a wide area and to evaluate each vegetation patch as wildlife habitat. Satellite image was utilized to extract vegetation patches and connectivity network was generated. Concept of landscape ecology was adopted for discussing the relationship between source and sink habitats.