Soil Properties And Seed Bank Of 4 Kinds Of Plant Communities In Desert Steppe Region

In this paper,the aboveground vegetation,soil characteristics and soil seed bank(SSB)of four kinds of plant communities(Community of Sophora alopecuroides,Community of Achnatherum splendens,Community of Artermisia ordosica,Community of Kalidium foliatum)were studied in desert steppe area of Ningxia Yanchi county by field investigation and laboratory experiment.The differences and correlation among aboveground vegetation,soil characteristics and seed bank of different 4 kinds of plant communities were compared respecitively.These results were helpful to reveal scientifically the successional law of plant communities in desert steppe,and provide some theoretical guidance for the management and restoration of degraded grassland.These results showed that:1.There were differences of 4 kinds of plant communities of aboveground part,such as species composition,life type and diversity characteristics.There were 15 species in S.alopecuroides community belonging to 7 families and 15 genera,respectively,in which Gramineae plants were accounted for one-third,and the number of perennial herb was 9.There were 14 species in A.splendens community belonging to 6 families and 11 genera,respectively.These species were mostly included Chenopodiaceae and Gramineae,in which 7 was the perennial herb.There were 10 species in A.ordosica community belonging to 6 families and 10 genera,respectively,in which Compositse and Gramineae account for half,and the difference of the plant life type were relatively high.There were only three species in K.foliatum community.The species evenness and stability of A.splendens community were higher,followed by S.alopecuroides community and A.ordosica community.The plants species of K.foliatum community were relatively single.2.There were discrepancies of the 4 kinds of plant communities about soil physical and chemical properties.For example,the soil bulk density was lower in S.alopecuroides community,but the total nitrogen and alkali-hydrolyzable nitrogen were higher.The pH and the organic carbon content of soil in A.splendens community were significantly higher than other communities.The soil moisture content and soil nutrients were lower in A.ordosica community.The salt content and the content of available P were relative higher in K.foliatum community.3.There were differences of 4 kinds of plant communities,such as soil enzyme activities,soil microbial quantity and their vertical distributions.The activities of soil urease and phosphatase in S.alopecuroides community and A.splendens community were higher.The activities of soil catalase in K.foliatum community were higher.The activities of soil phosphatase and sucrase were lower in A.ordosica community.The activities of urease,phosphatase and sucrase decreased with the increase of the soil layer in the 4 kinds of plant communities.However,the change of soil catalase were abnormal in K.foliatum community.The number of soil microorganisms in 4 kinds of plant communities showed a decrease trend with the deepening of the soil layer.It was the highest in S.alopecuroides community and was the lowest in A.ordosica community.4.There were differences of the 4 kinds of plant communities rearding species composition,seed density,distribution pattern and diversity characteristics of SSB.The number of species and seed density in A.splendens community were the highest,followed by S.alopecuroides community and A.ordosica community,and the lowest were the K.foliatum community.The seed density of dominant species in other three kinds of plant communities were low,except in S.alopecuroides community.The proportion of Gramineae,Compositae and Chenopodiaceae in the 4 communities was relatively high.The species number,seed density,diversity index,evenness index and richness index of SSB in 4 kinds of the plant communities were ranked as following:A.splendens community>S.alopecuroides community>A.ordosica community>K.foliatum community.The seed density in 4 kinds of plant communities decreased with the deepening of soil layer.In addition,there was the highest SSB between A.splendens community and A.ordosica community,but lowest similarity between A.ordosica community and K.foliatum community it was the lowest.5.The aboveground vegetation,soil characteristics and seed bank were closely related.Gramineae,Compositae and Chenopodiaceae plants of 4 kinds of communities appeared more on the aboveground vegetation and under soil seed banks.However,the species similarity of 4 kinds of communities between aboveground vegetation and SSB.The species similarity between aboveground vegetation and SSB of S.alopecuroides community was the highest,K.foliatum community the lowest.The seeds of perennial and annual plants was mostly in the SSB of the 4 kinds of plant communities,but the shrubs and semi-shrubs seeds was less.There was the difference between the life type composition and the aboveground vegetation.In the aboveground vegetation,the perennial plant of S.alopecuroides community,A.splendens community and A.ordosica community were the most,but the proportion of annual plant was few.There are no perennial in the K.foliatum community,and there were shrubs and annual plants,and mainly shrubs.The seed density of 4 kinds of plant communities increased with the enhancing of aboveground vegetation density,but their trends were different in 4 kinds of communities.The soil pH and total salt content effected significantly on the SSB,then the soil water content and the alkaline hydrolysis nitrogen.In addition,the soil phosphatase and urease influenced largely on,then sucrose.In general the soil microbial quantity had a few influenceon SSB.