Regulation Of Ecological Function Of Wetland Production In The Yellow River Delta

As an important part of the global ecosystem,wetland is mainly divided into natural wetland and constructed wetland,which play an irreplaceable role in maintaining the stability of the global ecosystem,sustainable utilization of resources and coping with climate change.In the Yellow River Delta,soil is the main obstacle to the structure and function of wetland due to the severe water and salt stress and poor soil fertility.However,soil controlling factors and their quantitative relationship with the structure and function of wetland are still not well understood,which restricts the practice of wetland ecological conservation and ecological service function improvement.Aiming at this problem,this paper takes the typical natural wetland（T.chinensis wetland）and constructed wetland（paddy field）in the Yellow River Delta as the research object,and uses the methods of field location observation and investigation,plot experiment and laboratory analysis to study the response characteristics of natural and man-made wetland plant communities to the soil habitat,and reveals the key controlling factors of the ecological production of natural and constructed wetland.This paper elucidated the regulation ways of soil habitat for key production ecological functions of wetland,and provided scientific basis for ecological conservation and function improvement of wetland in the Yellow River Delta.The main results of this study are as follows:（1）Through nutrient survey and location observation,it was found that the soil habitat conditions（bulk density,sand,clay,silt content,soil moisture,salinity,total-N,total-P,etc.）of T.chinensis wetlands at 10,20 and 40 km from the coastline were significantly different（P<0.05）.The difference of soil and habitat conditions significantly affected the growth and community diversity of T.chinensis.With the shortening of distance to the sea,the density,ground diameter and canopy coverage of T.chinensis community decreased significantly,and the Simpson dominance index,Pielou index and Margalef index of T.chinensis community changed significantly（P<0.05）.Soil sand content,moisture and EC were significantly correlated with Simpson,Pielou and Margalef indices（P<0.05）,indicating that soil texture,moisture and salinity are the main controlling factors determining the diversity of T.chinensis community.（2）The results showed that the plant height,panicle length,panicle number,grain number,1000-grain weight and seed setting rate of rice under saline irrigation were significantly lower than those under other treatments（P<0.05）.Pearson correlation analysis showed that rice yield and agronomic traits were mainly inhibited by soil salinity,total nitrogen and organic carbon,indicating that rice yield was significantly affected by salinity and nutrient content（P<0.05）,the theoretical maximum threshold of soil salinity generated by rice yield is 4.30 g kg^-1,beyond which the yield cannot be formed.The results indicated that the agronomic characters and yield of rice in the Yellow River Delta were mainly controlled by soil salinity.（3）Using principal component analysis（PCA）and based on soil sand content,water content and EC,the SHI index of soil habitat of T.chinensis community can predict the diversity of T.chinensis community linearly（R²=0.12～0.17,P=0.01～0.05）.The prediction results showed that the larger the SHI（the coarser soil texture,the higher soil salinity and the wetter soil moisture）,the Simpson dominance index and Pielou index gradually increased,and the Margalef index gradually decreased.Therefore,making the soil loamy and reducing salt and water may be the main ways to improve the ecological function of T.chinensis community.