Study On Quantitative Ecology Of Vegetation In Pinglu Section Of Yellow River, Shanxi

As an important component of wetland in Shanxi, the Pinglu Section of Yellow River is located inYuncheng City,Shanxi and it is the winter habitat of Cygnus cygnus and other waterfowls. Based on the field vegetation, the plant communities in Pinglu Section of Yellow River, Shanxi were studied by quantitative ecology methods including TWINSPAN, DCA, Spearman’s rank correlation, Fisher’s exact test and taxonomic diversity. The composition, distribution, correlation, diversity of species and relationship between vegetation and environment were analyzed, respectively. The aim of this study expected to present some scientific and theoretical basis for the conservation and management of plant communities and environment in Pinglu Section of Yellow River, Shanxi.The plant communities in Pinglu Section of Yellow River, Shanxi were classified into 7 associations by TWINSPAN. The results of DCA ordination of plots and species showed that the distribution of plots and were consistent with species, and the main effect factors were moisture conditions. The hygrophilous species were distributed in region of better moisture conditions, the drought tolerant species were distributed in region of poor moisture conditions.Plant functional groups (PFGs) in the wetlands of Pinglu Section of Yellow River, Shanxi were analyzed by Fisher’s exact test, Spearman rank correlation and TWINSPAN, respectively, based on the dataset from the field. The results showed that:(1) Based on the results of Spearman’s rank correlation,87 species-pairs had a positive association coefficient, of which 20 species-pairs had a highly significant positive association coefficient (P<0.01), however, only 1 species-pairs had a negative association coefficient which was significant (P<0.05);(2) By Fisher’s exact test,93 species-pairs had a positive association coefficient, of which 26 species-pairs had a highly significant positive association coefficient, yet 1 species-pairs had a negative association;(3)On the basis of results of the association and coefficient of species as well as that of analysis of clustering, the constructive and dominant species were divided into four PFGs:mesophyte PFGs, mesohydrophyte PFGs, hygrophyte PFGs and hydrophilous PFGs. Water is the leading factor to control the distribution of PFGs. The PFGs along the moisture gradient were distributed in the river and the marshland, the seasonal watering area of flooding plain, the lower of flooding plain and the top of flooding plain of Yellow River.A study of traditional diversity study focuses on the number of species in a given ecosystem. Traditional indices are extremely sensitive to the sampling method and sample size; changes in sampling efforts often significantly impact on the level of diversity in an ecosystem, and it is difficult to compare data sets collected at different times and regions. Taxonomic diversity is used to measure species diversity, and not only species abundances and distribution but also taxonomic relatedness are considered. Furthermore, this method is robust and minimally influenced by variables or uncontrolled sampling efforts. On the other hand, taxonomic evenness of an assemblage should also be considered. It not only reflects community diversity; but also provides information on the relationship between environmental factors and indirect disturbance, which are often applied to identify whether the ecological system or environment is undergoing degradation. To explore the species diversity in Yellow River Wetlands, Pinglu,Shanxi, and to test the application of taxonomic diversity in plant ecology,16 sites were chosen to around the Sanmenxia Dam, Pinglu and a species list was established. In the present study,368 species belonging to 213 genera,67 families and 36 orders were recorded in this region. Most of the species belonged to the families Compositae (54 species) and Poaceae (45 species). Plant species diversity was studied using average taxonomic distinctness (△-) and variation in taxonomic distinctness (Λ+) and a confidence funnel was obtained. The expected value of △+ and Λ+ were 74.24 and 480, respectively. No significant difference were observed among the different stands both upstream and downstream of Sanmenxia Dam and various community types (P>0.05). The average taxonomic distinctness values of Checun (62.28) and Biegan (67.41) which severely disturbed by human activities, were lower; and below the confidence limit. The average taxonomic distinctness values for Nangou Ferry and Sanwan Lake, which were sites with better water availability and less disturbance, were higher, (81.30 and 79.94,respectively). The value of Λ+ in Checun (814.44) was the highest, suggesting that the species distribution in this site was less homogeneous. The value of Λ+ in Jianbei (423.31) was the lowest, with species distribution being homogeneous. Traditional diversity methods hardly reflect species composition, distribution and diversity; and there is no certain correlations between taxonomic diversity and species number. The correlation coefficient between △+and S was 0.257(P>0.05), and that between Λ+ and S was-0.187(P>0.05). Anthropogenic activities such as cultivation and tourism are dominant factors that have caused the significant decrease in taxonomic diversity and non-uniform sapatial distribution of species of different taxa in Yellow River Wetlands.