| Plantation construction is an important and common engineering measure for restoration and management of degraded grassland in north China.Since the 1970s,the intervention of large-scale plantations has not only effectively contained the trend of land desertification,but also caused changes in the deep structure and function of ecosystems such as soil moisture and biodiversity.At the present stage,how to maintain the balance and sustainability of the integrated service functions of such ecosystems has become a major new issue for the country and the region.The relationship between soil moisture and biodiversity is one of the important research fields.in the central arid zone of Ningxia,the average moisture content is 6.78%.The average soil molsture content between 0 and 2m in grassland of different habitats showed a trend of increasing fluctuation and then decreasing,and the coefficient of variation increased with the increase of soil layer.20?40 cm and 40?60 cm soil layer is significantly higher than the average soil moisture content 0?20 cm soil layer,the grass of the active layer of soil water condition was significantly better than the active layer.that drought in central Ningxia with soil moisture is mainly focused on the depth of 20 to 60 cm soil layer,active layer of soil moisture content show the slope is significantly higher than sunny slope,slope to the difference is only affected the shallow soil moisture,had no significant effect of deep soil moisture.The soil moisture content in the soil layer of 0?20cm?80?100cm.100?120cm,120?140cm,140?160cm,160?180cm and 180?200cm on the shady slope was significantly higher than that in the same soil layer on the sunny slope.The grass community in the study area has entered the late stage of succession.Caragana consumes a lot of groundwater.resulting in the desiccation of the soil.Therefore,the existence of caragana has no effect on the soil moisture of the grassland in the arid zone of central Ningxia at the present stage.For further understanding of Ningxia in the nurture and grazing prohibition,returnin farmland to forest project,regional scale of artificial introduction korshinskii role in the degradation of grassland restoration.2018 in central Ningxia drought with typical desert regiondessavanes,a very short moment slope and slope contrast investigated artificial forest of caragana korshinskii and species diversity of natural grassland and soil moisture distribution and its correlation.Based on the statistical analysis of data from 37 spatial grids,148 habitat samples and 444 survey samples.the preliminary results show that:(1)The average soil moisture content of 0?200cm in different habitats was 6.78%.With the increase of soil layer,the soil moisture content first increased and then decreased,then increased,decreased and increased.The average soil moisture content of soil layer 20-40cm and 40-60cm was significantly higher than that of soil layer 0-20cm.The average water content of the shady slope was significantly higher than that of the sunny slope.The soil water content of the stratified soil was 0?20cm(active layer)and 80?200cm(active layer)higher than that of the sunny slope,indicating that the soil water condition of the shady slope was better.However,there was no significant difference in average soil moisture content or stratified soil water content between caragana forest and natural grassland.The introduction of caragana caragana into a large area did not cause significant decrease of soil moisture and significant change of its vertical distribution in the study area.(2)There were 48 species of plants,belonging to 15 families and 40 genera.In the community,compositae plants accounted for more than 50%,followed by leguminous plants and finally chenopodiaceae and gramineae plants,all of which accounted for more than 99%in different habitats.A.pigwort is the absolute dominant species of herbaceous plants in the study areac.stipa is the dominant species of perennial plants,and c.hu is the subdominant species.The diversity index of shannon-wiener,Pielou evenness index and Simpson diversity index ranged from 1.24-1.3,1.41-1.58,2.51-2.85 and 0.64-0.68 respectively.The species classification composition of caragana forest and natural grassland communities in the study area was similar,and there was no significant difference in species diversity.The interposition of caragana caragana and the change of slope direction only caused the change of the importance and coverage of individual species,but had no significant effect on the diversity of species and community structure in the study,area.Through correlation analysis,it can be seen that the soil moisture of grassland in the arid zone of central Ningxia has different effects on species diversity.In the overall situation,the study area grassland correlation between species diversity and soil moisture content of the active layer is larger,under the condition of different slope direction,slope correlation between species diversity and soil moisture content is larger.the grass under the condition of different cover,the introduction of caragana korshinskii grass correlation between species diversity and soil moisture content is larger,so in arid area of middle Ningxia slope,the introduction of caragana korshinskii grass and active layer of soil moisture content plays an important role in improving the grassland species diversity.174 5000(3)Through correlation analysis,it can be seen that the correlation between soil moisture in different soil layers and species diversity is different.Only the soil moisture content of the sub-active layer(20-60cm)was significantly correlated with species diversity under different or non-habitat conditions.Under different slope conditions,the relationship between soil moisture content and species diversity was stronger in the shady slope than in the sunny slope,and in the caragana forest than in the natural grassland.The introduction of caragana or the change of slope direction did not significantly change the basic pattern of the correlation between soil moisture and species diverslry.but it did affect the strength of the correlation.In conclusion,the artificial introduction of caragana in a typical desert steppe in central Ningxia did not cause significant changes in species diversity and community structure,nor did the artificial introduction of caragana have significant effects on the soil water status of grasslands in the arid zone of central Ningxia.As far as this study area is concerned,the soil moisture content of the sub-active layer(20-60cm)has a significant and unique indicator effect on species diversity,and the correlation between species diversity and soil moisture is not sensitive to habitat changes. |
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