Stability Of Typical Desert Plant Populations,Communities And Ecosystems Across Water-salt Gradient

The arid and semi-arid areas in the northwest are distributed with typical fragile ecosystems.Maintaining ecosystem stability is particularly important for the conservation and sustainable development of biodiversity in this area.This paper uses the desert plant ecosystem of the Ebinur Lake Wetland National Nature Reserve.For the research object,the changes of population,community and ecosystem stability under different water-salt gradients were discussed,and the factors affecting community stability were discussed from the perspective of environmental factors,diversity and complexity.The following conclusions were drawn:(1)The population stability under different water-salt gradients was the largest in the population of Herba Salsola collina and Suaeda salsa,and the stability of the population changed to some extent with the change of water-salt gradient.The coefficient of variation of species population density and the improved calculation method of Godron stability showed that the stability of community under different water-salt gradients was high water and salt > low water and salt > middle water and salt community.The ecosystem is in an unstable state.The stability at different scales is population > community > ecosystem stability.(2)There was a certain degree of change in species composition under different water-salt gradients.With the decreasing of water-salt gradient,the proportion of herbaceous decreased,the proportion of shrub decreased,and the change of arbor was more stable.Both the Simpson diversity index and the Pielou evenness index are the highest under high water and salt.In the middle water and slat is similar to the low water and salt.The Shannon-Wiener diversity index and the Margalef richness index are both the highest under low water and salt.There were significant differences in soil factors under different water-salt gradients.The results of plant diversity and soil factor RDA analysis showed that the soil factor explained 48.8% of plant diversity under the high water and salt gradient,10.5% of the salt in the middle water and slat,and 8.4% of the plant diversity under the low water and salt gradient.Species diversity has a significant effect on community stability,and this effect increases with decreasing water-salt gradients.(3)Functional diversity in different water-salt gradients showed high water and salt > low water and salt > middle water and salt.Under different water-salt gradients,the interpretation of the functional factors of soil factors on the functional diversity was ranked as high water and salt > low water and salt > middle water and salt,and the interpretative amount explained 68.9% functional diversity under high water and salt,respectively.Salt in water explained 11.2%,and low water and salt explained 15.8%.There was a positive correlation between species diversity and functional diversity under different water-salt gradients,and the correlation was the highest under low water and salt.There was a significant positive correlation between functional diversity and stability in high water,high salt and middle water.Under low water and salt,with the increase of functional diversity,the stability of the community first increases and then decreases.(4)Under different water-salt gradients,the total complexity of showed low water and salt > middle water and salt > high water and salt.The complexity of disordered structure in the middle water and salt > low water and salt > high water and salt.The salt gradient in water is significantly different from high water and salt,low water and salt,while the ordered structure complexity shows a trend opposite to the complexity of disordered structure.Under different water-salt gradients,soil factors accounted for 47.9%,8.4%,and 15.2% of community complexity,respectively.As the water-salt gradient decreases,the correlation between diversity index and community complexity increases.The stepwise regression of species diversity and functional diversity and community complexity shows that under high water and high salt gradient,functional diversity is important for the complexity of disordered structure,and it is positively correlated;The impact of functional diversity on complexity is negligible;species diversity under low water and salt gradients explains 18.5% and 18.9% of total community complexity measures and ordered structural complexity measures.(5)The interpretation of soil factors on community stability under different water-salt gradients was 58.3%,13%,and 22.3%,respectively.There was a negative correlation between community complexity and stability under different water-salt gradients.The community stability and functional diversity were positively correlated with high water and salt and middle water and salt gradients,and negatively correlated with total community complexity.With the decline of water-salt gradient,functional diversity and community complexity reduce the interpretation rate of stability;under low water and salt,community stability is positively affected by species diversity and functional diversity,The effect of disorder structure complexity negative effects.(6)The comprehensive analysis results show that under the high water and salt gradient,the complexity has a significant direct negative effect on the stability of the community.Under the salt gradient in the middle water,the species diversity has a significant positive effect on the stability of the community,and the functional diversity and complexity are Community stability has a very significant negative effect,and the effects of functional diversity on stability are direct effects.The indirect positive effect of species diversity on community stability is greater than the direct positive effect.The direct positive effect of soil available phosphorus and community stability is much greater than the indirect negative effect.Community stability is most affected by species diversity.The stability of community under low water and low salt was negatively affected by the positive effects of species diversity and pH,and the negative effects of functional diversity.The order of impact was the species diversity,functional diversity and pH.In summary,the community stability with enhanced species diversity provides strong support for the diversity-stability hypothesis;complexity reduces community stability and conforms to the complexity-stability hypothesis.