NICHE VARIATION OF DOMINANT HERBACEOUS PLANTS IN WATERLEVEL- FLUCTUATING ZONE OF THREE GORGES RESERVOIR AT THE BEGINNING AFTER CHARGING WATER

Authors Wang Xiaorong; Cheng Ruimei; Xiao Wenfa; Pan Lei; Zeng Lixiong

Journal Resources and Environment in the Yangtze Basin , 2016,3:25

Abstract Based on the periodical fluctuations of water level, the standing vegetation in two consecutive flooding years was investigated by a space-for-time substitution method in the water-level-fluctuating zone in Three Gorges Reservoir Area. Niche breadth and niche overlap were calculated and were further used to analyze the changes of the plants species niche breadth of the dominant herbaceous plants flooded for various periods. The results showed the niche breadth of the dominant plants before being flooded in the first flooding year was generally narrow and the niche breadth change was very significant. While in the second flooding year, the acclimatization of herbaceous plants to the moisture change increased. Before flooding, the number of species pairs with overlap value greater than 0.5 was only 125, and the number of species pairs with overlap value less than 0.2 was 189, among which, 103 species pairs overlap values are 0. After flooding, the number of species pairs with overlap value bigger than 0.5 was 24, the number of those with overlap value less than 0.2 was 53, and 6 of the 53 species pairs had an overlap value of 0, which indicated survival of the species that can acclimate to the environmental change from dry to wet condition, resulting in an increased overlap value of the dominant plant species. At the areas flooded for 2 consecutive years, Digitaria chrysoblephara displayed the biggest niche breadth in the first year, and the rest 17 species, which occupy 61% of all the dominant species, showed the niche breadth less than 0.2. In the second year of the two consecutive flooding years, Pouzolzia zeylanica and Eclipta prostrata displayed comparatively big niche breadth, and the rest 15 species accounting for 50% amount of all the dominant species showed niche breadths less than 0.2. Only 8 herbaceous plants are the species that survived in the two consecutive years. Also in the second year of the two consecutive flooding years, there were 17 species pairs with niche overlap values over 0.5, while the number of species pairs with niche overlap values of 0 was 2, indicating that flooding in two consecutive years helped to form a more homogenous ecological habitant, and the number of species acclimating to similar environment increased.

Species covered 鳢肠 Eclipta prostrata 雾水葛 Pouzolzia zeylanica