Application of Markov model in wetland change dynamics in Tianjin Coastal Area, China

Abstract

Abstract Wetland ecosystem is one of the most productive and most diverse ecosystems, which provides various important habitats for wildlife. However, the rapid urbanization caused wetland degradation. Thus, researchers all over the world pay attention to study on wetland dynamic changes in order to analyze the causes of wetland degradation. Tianjin Coastal Area is the center for the Bohai Bay. The government has prioritized integrating all the cities in the Bohai Bay Rim and fostering economic development in this area. Tianjin has various types of wetlands including coastal wetlands (estuarine waters, marshes, et al.), inland wetlands (rivers, lakes, et al.), and artificial wetlands (ponds, salt exploitation sites, et al.) according to classification in Ramsar Convention. The wetlands in Tianjin Coastal Area have high biodiversity and provide various ecological functions and values. With the development of this area, human disturbance have been increasing. The research on wetland change dynamics is the basic for wetland ecosystem protection and restoration. This area is the site of an intense land-use conflict among urbanization and natural protection. Large scale spatial and temporal land-use data were used to investigate the dynamics of wetland change in this area. Markov software was applied based on the support of GIS and RS from 1979 to 2008. The Markov chain was used as a stochastic model to make quantitative comparisons of the wetland changes between discrete time periods extending from 1979 to 2008. The wetland dynamic changes have been predicted according the Markov chain model in 2015, 2020 and 2050. Three main conclusions have been drawn from the Markov model about the wetland change dynamics in this area. (1)A continuing ‘exchange’ of wetland area occurs between artificial wetlands and natural wetlands categories that has little effects on the net amount of wetland but could undermine the long-term ecological function of remaining natural wetland in this area. (2) The human induced factors such as pollution and construction were the predominant causes for wetland changes. (3) The natural wetlands will be in great decline in 2020 and 2050 without enhancing wetland protection policy and increasing restoration technology. It is hoped that the dynamic model will serve as a laboratory to study the different features of the wetland problem in coastal area and to analyses different policy alternatives with an integrated, systemic approach.