Response Of Functional Characters Of Stipa To Environmental Gradient In Ningxia Grassland

Stipa is one of the most important forage plant resources in Ningxia natural grassland.It is of great significance to study the relationship between its functional characters and ecological factors in order to reveal the adaptive mechanism of Stipa and the restoration of grassland vegetation.In this paper,S.breviflora.S.tianschanica,S.caucasica,S.bungeana,S.grandis and S.glanacea were selected 15 typical plots of Stipa communities were set up along the environmental gradient from north to south.The functional properties of 13 leaves and roots and soil nutrient data of 6 Stipa species were measured.The relationship between the functional properties and soil and climate factors was analyzed.The effects of ecological factors on the work were revealed by redundancy analysis(RDA)and variance decomposition The contribution rate of energy characters and the ecological factors which have significant influence on the functional characters of Stipa were screened.The driving mechanism of the geographical alternative distribution of Stipa was explained by the theory of functional characters.The main conclusions are as follows:1)Among the functional characters of Stipa in Ningxia,plant height(F=1 15.728,P=0.000),specific leaf weight(F=29.336,P=0.000),leaf nitrogen content(F=12.784,P=0.000),leaf phosphorus content(F=4.020,P=0.005),leaf nitrogen phosphorus ratio(F=9.283,P=0.000),leaf nitrogen content per unit area(F=6.420,P=0.000)are the above ground functional characters,and root density is the underground functional character There were significant differences in the functional characters(F=11.688,P=0.000),root tip number(F=15.965,P=0.000),total root length(F=10.034,P=0.000),root nitrogen content(F=7.110,P=0.000),root phosphorus content(F=7.162,P= 0.000),root nitrogen phosphorus ratio(F=1 1.283,P=0.000).2)According to the correlation between the functional characters of Stipa,it can be concluded that plant height is positively correlated with root tip number,total root length and root phosphorus content,and negatively correlated with root total nitrogen and root nitrogen phosphorus ratio;specific leaf weight is negatively correlated with root total nitrogen,leaf phosphorus content per unit area,leaf nitrogen content per unit area and leaf total nitrogen content;leaf nitrogen content is negatively correlated with leaf nitrogen phosphorus ratio There was a significant positive correlation between leaf nitrogen content per unit area,leaf phosphorus content per unit area,root nitrogen content and root nitrogen phosphorus ratio;there was a significant positive correlation between leaf phosphorus content and root phosphorus content,root nitrogen phosphorus ratio;there was a significant negative correlation between leaf nitrogen phosphorus ratio and root density,and there was a positive correlation between root nitrogen content and root nitrogen phosphorus ratio;there was a significant positive correlation between leaf phosphorus content per unit area and leaf nitrogen content per unit area There was a significant positive correlation between root P content and leaf N/P ratio,root N/P ratio.Root density was positively correlated with total root length and apical density.3)The plant height,specific leaf weight,leaf nitrogen content,leaf nitrogen content per unit area and root total nitrogen content of Stipa leaf are greatly affected by rainfall.Similarly,root function traits(root density,number of root tips,total root length)were also inhibited by temperature.Solar radiation promoted leaf nitrogen,leaf nitrogen phosphorus ratio and root nitrogen content of Stipa.Soil factors have great influence on the above ground functional characters(plant height,leaf nitrogen content,leaf nitrogen content per unit area)of Stipa,and on the underground functional characters(root density,root total nitrogen,root tip number,total root length and root nitrogen phosphorus ratio).5)The results of redundancy analysis showed that the common explanation rate of the ecological factors was 96.1%.Among them,climate factors and soil factors accounted for 58.7%and 76.6%of the functions of Stipa,respectively.Therefore,the most obvious ecological factors affecting Stipa grassland were soil factors,followed by climate fectors.In terms of the proportion of interpretation,the soil scale influence is greater than the climate scale influence,and the soil factor is more dominant than the climate factor.5)According to the results of variance decomposition,the common explanation rates of ecological factors affecting the functional characters of Stipa were 19.5%,37.4%and 39.2%,respectively.Among them,among the ecological factors affecting the functional properties of Stipa,the climate factors are mainly solar radiation,rainfall,annual average temperature and temperature change in the growing season,while the soil factors are mainly affected by soil organic matter,soil nitrogen phosphorus ratio,soil water content,soil bulk density and soil nitrogen content.