Research on the correlation of bird changes with the net primary productivity in the pearl river estuary wetlandsa case of Mai Po inner Deep Bay Ramsar Site

Water birds is an important part of the wetland ecosystem. It plays a key role in energy conversion and maintaining stability of the ecosystem, moreover, it is also a sensitive index of wetland ecological environments investigation and calculation. As the bird population dropped sharply, more and more people pay attention to wetland birds study and protecting. At the present time, it becomes the focus of international research to investigate the population changes and distribution of wetland bird and study the effect of environmental factors on wetland birds. To develop efficient methods of generating information on the changes of wetland birds, the article reports on the potential of predicting wetland birds using the net primary productivity (NPP). A CASA model using TM to calculate NPP in Mai Po inner Deep Bay Ramsar Site was built, and examined the relationship of three measures of NPP-mean, maximum and standard deviation-with water birds´ population. Results showed that: TM is a good choose for NPP calculation in small areas; In the past 20 years, the NPP in Mai Po inner Deep Bay Ramsar Site had Significant fluctuations; The correlation between mean and the total number of birds were strong, so were standard deviation, but the correlation between the maximum and the total number of birds is very low; while there are positive correlation between NPP s-mean, maximum and standard deviation- and Chinese Pond Heron, Little Egret, Common Moorhen, Black tailed Godwit, Temmincks Stint, Marsh Sandpiper and Common Sandpiper; Building regression equations of these birds and the NPPs, results suggested that NPP can be a good choose for estimating and predicting the changes of birds under the influence of anthropogenic and natural disturbances.