Response of species composition and diversity of wetland communities to reclamation in Sanjiang Plain, China

As one of the three major ecosystems, Wetland has significance to global change. With the increasing population and improvement of technology, wetland has become one of the most seriously damaged ecosystems. This study firstly uses reclamation time as the index to reflect the disturbance intensity to study the species composition and diversity changes of wetland communities. The result shows: (1) there are 143 species in 25 wetland patches which belong to 43 families and 90 genera. The number of species increases firstly and then decrease with the increasing reclamation years, which reach the maximum value of 52 species in 11~15 years and then gradually decrease to 15 species in the late period of the reclamation, showing great variation. (2) There is great difference in species composition of wetland communities in different reclamation years. With the increasing reclamation years, chamaephyte plants decrease gradually while phanerophyte and annual plants increase. Plants changed from hygrophyte to mesophyte with the habitat changing. (3) α diversity of wetland community has the same trend with the richness index that they all increase firstly and then decrease with the expansion of reclamation time, and they all reaches the maximum after 11~15 years of reclamation.