Yellow River Delta Wetland Restoration Effects On Wetland Bird Communities

With more and more activities of using and changing wetland by human,wetland is facing with worldwide threat and has become one of the most degraded ecosystems.Therefore,in order to relieve the conflict between wetland degradation and wetland needs for human,wetland restoration is being served as an important compensation measure for wetland protection and utilization.But there have no studies on assessment on the effect of wetland restoration by present.Because wetland bird could be regarded as one of the monitors of environmental changes,studies on the structure and dynamics of bird community in restored wetland were conducted in order to assess the ecological functions and effect of wetland restoration effectively.Studies on the effect of restoration on wetland bird community were conducted using transect method and quadrat method by comparing the differences of structure,diversity and dynamics of bird community between two restored wetlands restored in different year and natural wetland at Yellow River Delta from March,2007 to February,2008.Furthermore, impacting mechanisms of wetland restoration on wetland bird community was also explored by comparing the changes of habitat factors in different type of wetlands.The study results were as follows.87 Species and 155764 individuals were observed during investigation,of which there were 29 species and 27534 individuals belonged to Charadriiformes,24 species and 85721 individuals to Anseriformes,11 species and 21559 individuals to Lariformes,10 species and 6626 individuals to Ciconiiformes,6 species and 8377 individuals to Gruiformes,2 species and 1903 individuals to Podicipediformes,2 species and 4035 individuals to Pelecaniformes,Anseriformes and Charadriiformes account for 72.72%,which were the codominant group of wetland birds in study area.There were differences in the composition of wetland bird communities among the different type of wetlands.Evenness of the group of wetland birds distributed in earlier restored wetland was lower than that in later one.This might be related with that the wetland restored earlier contained more individuals belonged to Charadriiformes and Anseriformes.There were differences of diversity and evenness of wetland birds among the three types of wetlands.Diversity of wetland birds was affected by species richness and evenness.The more species richness and higher evenness were,the higher diversity was.Diversity of wetland birds was the highest at ERW,and the lowest at NW in spring and throughout year.While diversity at ERW and LRW was lower than that at NW in summer and winter.This might be related with that the number of individuals of some species at restored wetland was too great to cause the evenness of wetland birds in ERW and LRW lower than that at NW in summer and winter. The effect of wetland restoration on wetland birds in 3 types of wetland was different.In general,The earlier restored wetland had higher species richness and abundance of wetland birds.77 species and 52.31%number of individuals distributed at ERW.Species richness was greater than that at the other two types of wetland,and abundance of individuals was extremely significantly greater than that at the other two types of wetland.In addition,species richness and abundance of Anseriformes,Charadriiformes and Ciconiiformes were both the greatest during northward migration at ERW.And species richness and abundance of Anseriformes were both the greatest in four seasons and whole year.Abundance of wetland bird community was highest in spring,autumn,and winter.Abundance of Gruiformes was also the highest in autumn.Further more,ERW was an important habitat used by Oriental White Stork(Ciconia boyciana)for roosting and foraging.Therefore,ERW was the most important and valuable wetland for wetland birds in study area.67 species and 33.94%number of individuals distributed at LRW.Where species richness and abundance of wetland birds were greater than that at NW.Species richness and abundance of Lariformes were both the greatest at 3 types of wetland in four seasons and throughout year,and species richness and abundance of Charadriiformes and wetland bird community were both the greatest in summer.Further more,LRW was significant to Saunder's gull(Larus saundersi) which was listed as first class in national protective animals for roosting and foraging.So LRW was also important for wetland birds.But the abundances of Gruiformes at ERW and LRW were both lower than those at NW except in autumn,this might be related with that the number of individual of Coot(Fulica atra atra)was highest at NW except in autumn.The abundances of Ciconiiformes at NW was highest except in spring,this might be related with that average water depth of NW was lower than that in the other two types of wetland.Although species richness and abundance at NW was the lowest,it was a key foraging habitat for Ciconiiformes and Gruiformes,especially when the water depth of the two restored wetlands was too higher in autumn and winter.In addition,potential habitat was important for Charadriiformes and Anseriformes there.Therefore,NW should be paid more attention and protected it effectively from further degradation as result of human disturbance.60 species and 36251 individuals of wetland birds were observed during spring investigation,of which 10 species and 2705 individuals(7.46%)of them belonged to Ciconiiformes,17 species and 14288 individuals(39.41%)to Anseriformes,16 species and 15772 individuals(43.51%)to Charadriiformes,9 species and 3134 individuals(8.60%)to Lariformes,and other species account for less than 1%.13 habitat factors were measured to characterize the restored habitat.9 were selected by PCA(Principal Component Analysis),which were reed coverage(RC),percentage of water area with no plant(PWWP),percentage of water area(PW),Percentage of water area with depth less than 10cm(PWⅠ),percentage of water area with depth between 10cm and 20cm(PWⅡ),percentage of water area with depth above 20cm (PWⅢ),percentage of plant within 1km(PP1km),percentage of water area with no plant within 1km(PW1km),percentage of plant within 0.5km(PP0.5km),percentage of water area with no plant within 0.5km(PW0.5km).The result of Pearson's correlation analysis showed that the species richness and abundance of Gruiformes and the species richness of Anseriformes had insignificant correlation with any habitat factors.This result indicated that none of these factors of the wetland could influence the characters of bird community.Otherwise,the species richness and the abundance of Ciconiiformes,Charadriiformes,Lariformes,and all wetland bird community and the abundance of Anseriformes had significant or extremely significant correlation with most of habitat factors, which meant that the presence and abundance of wetland birds might be influenced by both habitat factors in sample and those around sample.The key habitat factor that influenced the distribution of wetland birds in plot was selected among all habitat variables by stepwise multiple regressions.At least one of SS1,SS2 and SS3 was contained in 9 regression models,which indicated that the depth of water was the key habitat factor influencing the distribution of wetland birds.4 models contained MS1km or ZB0.5, which indicated that landscape characteristics were also the key factors influencing wetland bird community.And LWGD was also an important factor accounting for the abundance of wetland bird community.Combining with the result of regression models between the habitat factors and species richness and abundance of wetland birds,the result of ANOVA for habitat factors of 3 types of wetland in spring showed that there was extremely significant difference in 8 habitat factors among 3 types of wetland which indicated that the difference of bird community was related with the difference of habitat factors.Therefore,wetland restoration might affect the wetland bird community by altering habitat factors used by wetland birds.Basing on above research results,some management recommendations could be given that up-and-down depression area should be made in the bottom of restored wetland in order to maintain water depth at different level to make the restored wetland available for waterfowls and shorebirds,the area of vegetation in LRW should be increased in order to make it supply more food and refuge for wetland birds,area of hillock in restored wetland should be increased in order to protect roosting habitat for Saunder's gull,natural habitat conservation should be strengthened and prevent it from further degradation,the area of restored wetland should also be enlarged in order to provide more available habitats for wetland birds.