Quantitative Ecology Research Of Wetland Plant Community Of The Chayegang Marshland Near Henghu Farm In The Poyang Lake Region

Wetland plants are regarded as important ingredient of wetland ecosystem,it will provide great help for wetland biodiversity conservation and wetland ecosystem management if devote to quantitative ecology research of plant community.The 19 sampling plots(5m × 5m),95 sampling quadrates were laid out in Chayegang marshland of the Poyang Lake region in October 2015,based on sampling quadrates,the plant and soil data were surveyed,the plant community of marshland is surveyed particularly by virtue of quantitative ecology.Include plant species distribute,the relationships between species diversity and soil factors,plant interspecies relationships,niche characteristic of plant population on five resources-environmental gradients in a typical marshland in the Poyang Lake wetland,model fitting of plant species-abundance distribution pattern along elevation gradient in the communities of a typical marshland in the Poyang Lake region.The results can be listed as follows:Spearman rank correlation coeffients were calculated between soil factors(soil pH,electrical conductivity,moisture,organic matter,the following is same with it)with Shannon Wiener diversity index H',species richness index S and Pielou evenness index J,the relationships of species distribution and soil factors were detected by RDA(redundancy analysis).The results showed:(1)There was a highly significant positive correlation(p<0.01)between H' with soil pH and a significant positive correlation between S with soil pH(p<0.05),it had a highly significant negative correlation(p<0.01)between H' with soil organic matter and a significant negative correlation(p<0.05)between S with soil organic matter,however,the Pielou evenness index J and soil factors had no a obvious correlation.(2)The soil pH and the soil organic matter were the major soil factors that control the species distribution.The 45 species-pairs from the 10 major species in the catalog were inter-matched to explore the relationships between the plant species through 2×2 contingency table.The methods of variance rate analysis,?2 test,Jaccard index,pearson and spearman rank correlation analysiswere used to explore the relationships between the plant species,and ecological species groups were classified using ordination of principal component analysis.(1)The results of variance rate analysis showed that there was no significant correlation between 45 species-pairs;(2)that of ?2 test indicated that the relationships of only 3 species-pairs were significant correlation relationship(p?0.05).(3)The result of pearson correlation analysis revealed that only 9 species-pairs passed significance test of p?0.05.(4)Spearman rank correlation analysis found that only 14 species-pairs passed significance test(p?0.05).(5)There were 3 ecological species groups identified by principal component analysis from the 10 major plant species.The indices of Levins niche breadth and Pianka niche overlap were used to study plant population niche in this typical wetland.Results showed that:(1)The dominant species in the region were Carex cinerascens and Phalaris arundinacea,which had higher niche breadth in the five resources-environmental gradients.On the contrary,some occasional species in the community,Cyperus michelianus,Rorippa cantoniensis,Phragmites australis and other herbaceous plants had lower niche breadth in the five environmental gradients;(2)There were generally smaller niche overlaps among 10 plant species,but exception exists.Higher niche overlaps were found among Eleocharis valleculosa,Cyperus michelianus and Rorippa cantoniensis than other plant species pairs;(3)There existed significant(p<0.05)and highly significant(p<0.01)positive correlations between niche breadth and importance value(IV),but highly significant(p<0.01)negative correlation was found between niche breadth and the coefficient of variation of IV.Four niche models were employed to simulate plant species-abundance distribution pattern at elevation gradient.Results showed:(1)Along with the elevation dropped,the number of occasional species was declining gradually,whose average coverage persistently became lower;meanwhile,the number of common species remained unchanged and the average coverage and the average height of the dominant species Carex cinerascens were steadily increasing,which occupied higher dominating position in the community;(2)The species-abundance distribution pattern in the whole areas of high elevation,medium elevation and low elevation were fitted best by the niche preemption model(p<0.05;AIC values were-149.41,-61.11,-25.63 respectively);while the broken stick model,the overlapping niche model and the dominance preemption model showed poor fit effect at the elevation gradient in general(p<0.05;But the AIC values were all larger).