Variation Of Aquatic Macrophytes,and The Morphology Of Lake Shorelines,and Their Relationship Between Them

Characteristic of lake shorelines signifcantly influence growth,distribution and divisity of aquatic plants.It is of great significance to study the effect of characteristic of lake shorelines on aquatic plant divisity,especially on restoring the damaged lake ecosystem and maintaining the function and the structure of lake ecosystem.In this study,Global Position Technique(GPS)and Geographical Information System Technique(GIS)along with Transect Sampling method were used to study the variation of aquatic macrophytes diversity and the morphology of lake shorelines,and the their relationship.The main results are as follows:(1)There were 93,110,68,75,60,51 and 54 macrophytes species found in the Lake Honghu,Liangzi,Changhu,Xiliang,Futou,Huanggai and Wuhu in 2013,respectively.Among them,the dominant families are Gramineae,Cyperaceae Asteraceae and Polygonaceae.Based on the life form,18,11,6,8,9,4 and 4 species belonged to submerged plants;8,7,2,3,3,4 and 4 species belobged to floating-leaved macrophyte;7,5,5,4,5,2 and 2 species belonged to floating plants;6,4,4,3,4,5,5 species belonged emergent aquatic plants,and 71,66,51,57,41,36 and 36 species belonged to hygrophyte in the seven lakes,respectively.(2)Compared with historical data of 1990s,the species of aquatic plants in Lake Liangzi were increased by 18 within the latest 25years.among them,the species of submerged plants increased by 2,the species of floating-leaved macrophyte reduced by 6,the species of floating plants reduced byl,the species of hygrophyte and emergent aquatic plants increased by 23.The species of aquatic plants in Lake Honghu reduced by 18,within them,the species of submerged plants reduced by 8,the species of floating-leaved macrophyte reduced by 5,the species of floating plants reduced by 4,the species of hygrophyte and emergent aquatic plants reduced by 13.The species of aquatic plants in Lake Changhu increased by 28,within them,both the submerged plants and the floating-leaved macrophyte reduced by 4,the species of hygrophyte and emergent aquatic plants increased by 36,the species of floating plants reduced has no change.The species of aquatic plants in Lake Futou reduced by 43,within them,the species of submerged plants reduced by 8,the species of floating-leaved macrophyte reduced by 11,the species of floating plants reduced by 4 and the hygrophyte and emergent aquatic plants reduced by 20.The species of aquatic plants in Lake Wuhu reduced by 4 within the latest 22 years.The result indicate that the trend of species of aquatic plants in freshwater lakes of Jianghan plain District were declined in the past 22 years except for the hygrophyte and emergent aquatic plants.While the dominant families didn't changed dramstically during this period.The results indicate that lake deposition,reclamation of the wetland and fish-farming near the shoreline region will reduce the aquatic plant diversity due to aquatic plants.habitat loss.(3)Both the area and perimeter of these seven lakes were decreased at a high rate of speed since 1991.The perimeter of Lake Liangzi,Honghu,Changhu,Xiliang,Futou decreased by 168km(54%),161km(27%),78km(25%),281km(58%),208km(62%),separately.The area of these seven lakes decline rapidly before 1950s,hereafter the decreasing trend slowed down or even increased.Compared with their largest area,the area of Lake Liangzi,Honghu,Changhu,Xiliang,Futou,Huanggai,Wuhu decreased by 54%,67%,37%,58%,63%,77%,92%separately.and they decreased by 20%,63%,12%,27%,24%,27%,28%compared with 1950s.And compared with 1990s,the area of Lake Liangzi just decreased 4.3km2,Lake Honghu decreased 101.4km2,Lake Changhu increased 5.9km2,Lake Xiliang increased 11.9km2,Lake Futou increased 4.3km2,Lake Huanggai decreased 12.2km 2,and Lake Wuhu increased 1.8km2.As for the shoreline development index(SDI),the SDI of Lake Honghu,Liangzi,Changhu,Xiliang,Futou,Huanggai and Wuhu are 14.56,11.27,10.4,7.86,4.96;4.82,3.35,respectively in 2013,which indicate that lake shorelines of Lake Liangzi,Lake Changhu,Lake Xiliang,Lake Futou are more complex than the rest three lakes.(4)Correlation analyses suggested that there was a positive correlation between SDI and the number of Family&Genus and the number of floating plants.And the L/A positively influenced the number of floating-leaved macrophyte and emergent aquatic plant.However,the characteristics of lake shore lines didn't significantly influence the diversity of submerged plants and hygrophyte.