Spatial emergy analysis of agricultural landscape change: Does fragmentation matter?

摘要

Approximately 17% of agricultural lands in the western plain of Taiwan were converted to other uses during 1971–2006 due to rapidly industrial and urban development and high population density. Previous studies on the loss of farmland due to urbanization have focused on changes in the agricultural landscape such as fragmentation and irregular shape of farmlands. The shrinkage and fragmentation of agricultural land due to urbanization not only reduces food production but also results in the decrease and degradation of other agro-ecosystem services. Emergy synthesis has been used to assess land use changes in agricultural lands. However, the relationship between farmland fragmentation and the energy flows in agricultural systems has not been studied. This paper investigates empirically how ecological energetic flows of agricultural land were affected by landscape change in the western coastal plain of Taiwan by using emergy synthesis to assess the changes in ecological energetic flows of agricultural systems in each township from 1971 to 2006. Landscape metrics were also chosen to analyze the agricultural landscape change in each township. These metrics were then correlated with the results of emergy synthesis to study the relationship between farmland fragmentation and energy flows in the agricultural system. The results show that the fragmentation of farmlands tends to intensify the inflows of goods and services from the human economic system for farmland operations. For the counties closer to metropolitan areas, maintaining larger farm sizes and preventing farmland fragmentation decreases the proportion of resource inflows from the economic system and mitigates environmental loading in agricultural systems.