Mechanism Of The Effects Of Typical Temperate Desert Plant Diversity On Ecosystem Function

The study of the relationship between plant diversity and ecosystem function(BEF)has become a hot issue in ecological research in recent years.Exploring the potential linkages between the two is conducive to a comprehensive understanding of the theory of predicting ecosystem function.This paper takes the Aibi Lake Wetland National Nature Reserve as the research object,and carries out field work such as species survey,biomass mining and soil collection on the desert plant community in the study area,focusing on the primary ecosystem productivity and plant carbon storage.Taking species diversity,functional diversity,functional traits and soil factors as research directions,the changes of plant diversity under the water-salt sequence,the response of ecosystem functions to environmental and functional traits,and the response of biomass allocation to soil factors were discussed.And the effects of allometric growth and plant diversity on ecosystem function,the results are as follows:(1)According to the water-salt gradient sequence,the Pielou evenness index,the Shannon-Wiener diversity index,the Simpson dominance index,and the Rao index all show low water-salt gradient>middle water-salt gradient,and the four diversity indices are high.There was no significant difference between water-salt gradient and medium-low water salt.The Patrick richness index had no significant difference among different water-salt gradients.The correlation coefficients of Patrick richness index,Shannon-Wiener diversity index and Simpson dominance index under the water-salt gradient and functional diversity Rao index are:salt community in middle water>high water and high salt community>low water and low salt community.The power function regression model of Pielou evenness index and Rao index is as follows:high water and high salt community>low water and low salt community>salt community in water.(2)There are significant differences in functional traits between different life forms of plants.The leaf area,leaf dry matter content,leaf carbon content and leaf phosphorus content of perennial herb were higher than that of annual herb and shrub.The leaf nitrogen content and leaf nitrogen-phosphorus ratio of shrub were significantly higher than that of herb,but had the smallest leaf phosphorus content;There was no significant difference in leaf carbon to nitrogen ratio between shrubs;The fading ability of desert plants to absorb nutrients and the corresponding ability to capture light has a convergent comprehensive adaptation feature.The carbon-nitrogen ratio and nitrogen-phosphorus ratio of leaves were significantly correlated with specific leaf area and plant height.The amount of carbon sequestration in different life-type desert plants was as follows:perennial herb(9.08±1.55 g/m~2)>shrub(5.66±0.81 g/m~2)>annual herb(3.16±0.28 g/m~2);underground carbon sequestration In order:shrub(14.72±3.94 g/m~2)>perennial herb(8.54±1.33 g/m~2)>annual herb(1.33±0.10 g/m2).Among them,the total carbon fixation of the roots of the plants was:shrub(72.2%)>perennial herb(48.5%)>annual herb(29.6%).(3)Crown area,plant height,leaf nitrogen content,leaf nitrogen and phosphorus ratio have significant positive effects on desert plant primary productivity and carbon storage,and leaf carbon to nitrogen ratio has a negative driving force for desert plant primary productivity and carbon storage;Soil organic matter,available phosphorus,total nitrogen and soil pH were the main soil driving factors for aboveground biomass of desert plants.The order of soil fertility factors was:soil organic matter>total nitrogen>quick phosphorus>soil pH;soil water content,soil Organic matter and soil pH are important soil driving forces for the underground biomass of desert plants,and the underground biomass has a very significant positive correlation with soil water content.The order of importance of soil driving factors is soil water content>soil organic matter>soil pH;the direct action coefficient of soil factors on plant carbon storage is:soil water content>soil salinity>soil organic matter>soil total phosphorus>soil pH>Soil available phosphorus>soil total nitrogen.(4)The interpretability of edaphic factors towards R/S in terms of Seriphidium kaschgaricum,Suaeda salsa,Alhagi sparsifolia,Horaninowia ulicina are 16.3%,24.8%,33.1%,and 35.4%,respectively.Among them,the soil total nitrogen has a positive correlation with the R/S of Horaninowia ulicina(P<0.05),and the soil moisture a significant positive correlation with the R/S of Suaeda salsa(P<0.01)The four plants all have significant correlations with regards to AGB-BGB(P<0.01),where the AGB-BGB of Seriphidium kaschgaricum had a pattern of isometric scaling(?=1),while Horaninowia ulicina and Alhagi sparsifolia both showed an allometric scaling of?=3/4,and Suaeda salsa belongs to the allometric scaling of a non-3/4power exponent(?<1).All the four plants share a common allometric scaling index(0.767).The above results indicate that the desert plants in Ebi Lake have functional convergence,and the characteristics of their spatial distribution are species-specific in response to edaphic factors.(5)For primary productivity,under the high water and high salt gradient,the plant diversity index can explain the above-ground biomass fitting curve:Pielou evenness index>Simpson dominance index,only Pielou uniformity for total biomass.The degree index is significant;in the middle water salt gradient,the interpretation ability of the subsurface biomass fitting curve is:Rao index>Patrick richness index>Shannon-Wiener diversity index>Simpson dominance index;low water level Under the salt gradient,only the Simpson dominance index passed through the test for underground biomass.For plant carbon storage,under the high water and high salt gradient,the ability of plant diversity index to interpret the above-ground carbon storage fitting curve is:Pielou evenness index>Simpson dominance index>Rao index,only total carbon storage The Pielou evenness index passes the significance;in the middle water salt gradient,the explanatory power of the fitted curve of the underground carbon storage is:Rao index>Patrick richness index>Shannon-Wiener diversity index>Simpson dominance index,for the total The explanatory power of carbon storage is:Shannon-Wiener diversity index>Patrick richness index;under the low water and low salt gradient,only the Simpson dominance index of underground biomass is tested.