Effects Of Different Improvement Measures On Biomass And Plant Community Diversity Of Alpine Degraded Grassland In Northern Tibet

Alpine grassland is one of the main vegetation types in the Qinghai-Tibet Plateau ecosystem.It is also an important animal husbandry production base in China.It has many functions such as purifying air,regulating climate,preventing wind and sand,hydrological regulation,and animal habitat.It is essential for the Qinghai-Tibet Plateau ecological barrier.In recent years,due to climate change and human unreasonable disturbance activities,grassland in northern Tibet has been seriously degraded.Therefore,it is imperative to seek reasonable and efficient improvement and restoration measures to maintain the balance of the Qinghai-Tibet Plateau ecosystem.In order to explore the effects of watering,drilling and fertilization on the restoration of alpine degraded grassland,the high-cold degraded grassland in northern Tibet was taken as the research object,and the long-term positioning experiment of grassland restoration under different treatments was carried out by contrast method.The conclusions are as follows:Under the watering treatment,the number of species in the community was 13 in 2018,and the number of species in the community was 11,in 2016,12(2018)and 9(2016)higher than the control;The Pielou evenness index was 0.35 in 2018 under watering treatment.It is1.03 times of the control(0.34).The Pielou evenness index of watering treatment in 2016 is 0.47,which is 1.15 times of the control(0.41),but the difference between treatments is not significant(P>0.05);2018 under watering treatment the above-ground biomass of dominant species was18.87 g/m~2,which was 1.37 times of the control(13.74g/m~2),and the difference between treatments was significant(P<0.05).The aboveground biomass of the dominant species in watering treatment in 2016 was 8.09g/m~2,which was 1.25 times that of the control(6.48 g/m~2).The difference between treatments was not significant(P>0.05),indicating that the watering treatment was effective by increasing the soil Moisture,meet the growth and development needs of wet xerophytes,increase the dominant species,common species density and dry matter accumulation,promote the germination of occasional species in the community,thereby increasing the number of community species,the Pielou evenness index,and improving the grassland in northern Tibet.Ecosystem stability.Under the watering and perforation treatment,the dominant species density was 3 650.00 plants/m~2in 2018,which was 2.04 times that of the control(1 787.00 plants/m~2).The difference between treatments was significant(P<0.05).In 2016,the dominant species density of watering and perforation treatment was 400.00 plants/m~2was 1.04 times of the control(385.33 strains/m~2),and the difference between treatments was not significant(P>0.05).The total density of the community in 2018under watering and perforation was 7093.00 plants/m~2,which was 3.01times of the control(2364.67 plants/m~2),the total density of watering and perforating treatment community in 2016 was 590.67 plants/m~2,which was 1.01 times of the control(582.67 plants/m~2).The difference between treatments was not significant(P>0.05);The Shannon-Wiener diversity index was 0.75 in 2018,which was 1.01 times of the control(0.74).In2016,the Shannon-Wiener diversity index was 0.84,which was 1.09times that of the control(0.77).The difference between treatments was not significant(P>0.05);The Simpson diversity index was 0.24 in 2018under watering and perforation treatment,which was 1.09 times that of the control(0.22).The Simpson diversity index of watering and perforation treatment in 2016 was 0.28,which was 1.12 of the control(0.25).The difference between treatments was not significant(P>0.05),indicating that watering and perforation increased the soil.Breathability and water permeability enrich the seed bank,promote the absorption and utilization of root nutrients,and increase the plant density and species richness,which is conducive to the restoration of degraded grassland vegetation.Under the watering and perforating fertilization treatment,the total density of the community in 2018 was 3,286.67 plants/m~2,which was1.39 times that of the control(2364.67 plants/m~2).In 2016,the total density of the community under watering and perforated fertilization treatment was 586.67 plants/m~2,which was 1.01 times of the control(582.67 plants/m~2),the difference between treatments was not significant(P>0.05);The dominant species biomass in the 2018 year under watering and perforated fertilization treatment was 16.97 g/m~2,which was 1.24times of the control(13.74 g/m~2),the biomass of the dominant species in watering and perforating treatment in 2016 was 7.49 g/m~2,which was1.16 times of the control(6.48 g/m~2),but the difference between treatments was not significant(P>0.05);Watering and perforation under fertilization treatment,the total dry matter mass of the community in2016 was 27.58 g/m~2,which was 1.42 times of the control(19.42 g/m~2).The difference between treatments was not significant(P>0.05).Under the watering perforation and fertilization treatment,the 2016 community Shannon-Wiener diversity index was 0.66,which was lower than the control(0.77).The Simpson diversity index of the community was 0.21in 2016 under watering and perforated fertilization treatment,which was lower than the control(0.25),indicating that watering and perforating fertilization provided vegetation growth.Good water and nutrient environment,meeting a variety of plant growth needs,resulting in interspecies the competition is intensified and the diversity of the community is declining,but the dominant species are more prominent and the overall productivity of the community has been improved.In summary,watering,watering and perforating,watering,perforation and fertilization have a good promotion effect on the restoration of alpine degraded grassland and the stability of grassland ecosystem.Among them,watering,perforated and fertilization treatment is beneficial to promote the germination of common species and occasional species,increase the total density of the community,and increase the total productivity of the community.It is most suitable for promotion in the northern Tibet area dominated by animal husbandry.