WATER LEVEL FLUCTUATIONS DETERMINE THE SPATIAL AND TEMPORAL DISTRIBUTION OF MANCHURIAN WILD RICE (ZIZANIA LATIFOLIA) IN SIX YANGTZE RIVER FLOODPLAIN LAKES, CHINA

摘要

Zizania latifolia is a common emergent macrophyte in lakes along the lower reaches of the Yangtze River. To investigate the factors driving the expansion or decline of Z. latifolia populations, the spatial and temporal distribution patterns of Z. latifolia in six Yangtze floodplain lakes were analyzed from 2007 to 2016 using remote sensing and geographic information system tools. In combination with hydrological data and other environmental factors, the main influencing factors were determined. The results showed that distribution of Z. latifolia among the six lakes exhibited obvious differences. Plant cover was the highest in Wuchang and Huangda lakes, which had relatively stable water levels. Spearman correlation analyses showed that the lake morphological variables, climatic variables, and water quality variables had no significant effects on the distribution of Z. latifolia. Regarding variables related to hydrology, excluding the rate of water level change and timing of extreme water level annually, the other four groups of hydrological variables (a total of 20 indicators) all had significant effects on the distribution of Z. latifolia. At last, the reasons for difference in cover in different lake types were analyzed and appropriate strategies for the ecological management of Z. latifolia populations in different lake types were recommended.