| The research selected the degraded sub-alpine meadow community restoration chronosequences as the experimental site locates in the Nalati sub-alpine meadows conservation area,Xinyuan county,Yili,Xinjiang(82°08′47″E,43°04′57″N,2446 m).In July2018,the experiment established three 20 m×20 m plots with 50 m intervals and within each plot randomly designed four 1 m×1 m quadrats,overall twelve 1 m×1 m quadrats.In July 2018,July 2019 and July 2020,the research investigated the community compositions and sampled the above ground biomass in the quadrats.The research observed overall 46species from 20 taxonomical families,and the species were classified into the erects including12 species,the clusters including 24 species,the rosettes including 3 species and the creepers including 7 species according to the plant growth forms and classified into the grasses including 9 species,also the forbs including 33 species and the legumes including 4 species according to the functional groups.The results summarized as following:1.The differences between the species numbers(13.4±2.4)of the first year and the species numbers of the second year(13.6±2.7)were insignificant(P=0.988),whereas the species numbers(19.3±3.1)of the third year increased significantly than the species numbers of the first year(P<0.001)and the second year(P<0.001).The Shannon-Wiener diversity indexes between the first year(0.82±0.07)and second year(0.84±0.10)were insignificant(P=0.852),whereas the Shannon-Wiener diversity indexes(0.96±0.12)of the third year were significantly higher than the values of the first year(P=0.004)and the second year(P=0.017).2.On the first year 19 species were observed and the second years 34 species were observed respectively,which included 15 common species,4 reduced species and 19increased species,the Bray-Curtis(CN)βdiversity index was 7.54 and the S?renson(O)similarity index was 0.57.On the first year and the third year 36 species were observed,which included the 15 common species,4 reduced species and 25 increased species,the Bray-Curtis(CN)βdiversity index was 7.82 and the S?renson(O)similarity index was 0.55.On the second year and the third year,which included the 24 common species,10 reduced species and 12 increased species,the Bray-Curtis(CN)was 6.08 and the S?renson(O)similarity indexes was 0.69.Comparing with the first year,the Bray-Curtis(CN)βdiversity indexes of the second and the third year increased,whereas the S?renson(O)similarity indexes decreased.3.On the first year,the grass biomasses(24.1±4.3 g/m~2)were significantly lower than the grass biomasses of the second year(125.15±23.72 g/m~2)(P<0.001)and the third year(125.3±30.91 g/m~2)(P<0.001),the grass biomasses differences between the second year and the third year were insignificant(P=0.254);on the first year,the grass biomass percentages(21.1±3.7%)were significantly lower than the grass biomass percentages of the second year(39.2±5.4%)(P<0.001)and the third year(39.8±7.0%)(P<0.001),the grass biomasses percentages between the second year and the third year were insignificant(P=0.193).On first year,forbs biomasses(79.6±12.1 g/m~2)were significantly lower than the forbs biomasses of the second year(192.03±42.71 g/m~2)(P<0.001)and the third year(184.0±18.6 g/m~2)(P<0.001),the forbs biomasses differences between the second year and the third year were insignificant(P=0.478);on the first year,the forbs biomass percentages(69.3±5.7%)were significantly higher than the forbs biomass percentages of the second year(59.4±6.7%)(P<0.001)and the third year(59.5±7.0%)(P=0.022),the forbs biomasses percentages between the second year and the third year were insignificant(P=0.162).On the first year,legumes biomasses(10.9±2.6 g/m~2)were significantly higher than the legumes biomasses of the second year(3.91±8.59 g/m~2)(P=0.007)and the third year(2.1±1.5 g/m~2)(P=0.001),the legumes biomasses differences between the second year and the third year were insignificant(P=0.678);on the first year,the legumes biomass percentages(9.6±2.6%)were significantly higher than the legumes biomass percentages of the second yea(1.4±3.4%)(P<0.001)and the third year(0.7±0.5%)(P<0.001),the legumes biomasses percentages between the second year and third year were insignificant(P=0.792).On the first year,overall biomasses(114.6±12.1 g/m~2)were significantly lower than the overall biomasses of the second year(321.09±53.50 g/m~2)(P<0.001)and the third year(311.4±31.3 g/m~2)(P<0.001),the overall biomasses between the second year and the third year were insignificant(P=0.793).In sum,comparing with the first year,the grass biomasses,the forb biomasses and the overall biomasses increased significantly in the second year and third year,while the legume biomasses decreased significantly,the biomass percentages of the grasses increased significantly and biomass percentages of the legume biomasses decreased significantly.Within each observation year,the forb biomasses were significantly higher than the biomasses of the grasses and legumes,the grass biomasses were significantly higher than the legume biomasses.The research results of the analysis on the community composition of the Nalati degraded sub-alpine restoration chronosequences can be interrelated to the degraded grassland theoretical exploration,regional eco-security conservations and grassland live-stock industries sustainable development practices. |
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