Effects Of Improvement Measures On The Plant And Soil Of Degraded Alpine Meadow

Under the dual impact of global climate change and long-term overgrazing,the alpine grassland has been showed different degrees degraded in Qinghai-Tibetan,and leading to the further decline of grassland biodiversity and ecological service function.Therefore,according to different degradation degrees grassland,corresponding improvement measures were taken to improve ecology-production of degraded alpine grassland,and to curb the trend of grassland degradation.This paper study that effect of improvement measures(fenced grassland,reseeding,single sowing and mixed sowing grasslands)on grassland productivity,species composition,and biodiversity.The change characteristics of soil physical and chemical properties were analyzed and to discuss the response of vegetation and soil.It is expected that the restoration of degraded grassland management,protection and sustainable development of alpine grassland ecosystem to provide theoretical and basic data in the Qinghai-Tibetan Plateau.The main following results:(1)On the spatial scale,with different degradation degree,the grassland productivity and diversity were significantly restored during the restoration process of each improvement measure.The light degraded alpine grassland have obvious recovery effect in short time under enclosure measures.On the time scale(2016-2019),the composition of the grassland community changed significantly at different improvement measure.The species composition was influenced by different plant functional groups at different improvement measure.With the increase of restoration time,the grass functional group influencing the community composition is also falling.The impact of improvement measures on species diversity varies with different measures.The species diversity of each improvement measure showed different dynamic changes with the increase of improvement years.The stability of grassland community productivity all changed by different improvement measures.Increased species diversity lead to reduce of grassland aboveground productivity,while the plant community productivity affects community stability with the with the increase of restoration time,and the improvement of plant diversity improves the stability of the grassland.The change of plant diversity at the improvement measures promoted stability of grassland.(2)The grassland of reseeding,single sowing and mixed sowing measures all increased the surface water content of the soil;the fenced measures lowered the p H of soil,while the p H of soil in each sowing layer of reseeded sowing,single sowing and mixed sowing measure changed with the improvement of the period.Compared with moderately degraded alpine meadows,reseeding measures have no significant effects on soil available nutrients in 0-30 cm soil layer.Compared with heavily degraded alpine meadows,single sowing measures have significant effects on soil nitrate nitrogen in 0-30 cm soil layer.However,it has a significant impact on 0-10 cm and 20-30 cm soil ammonium nitrogen.Single sowing and mixed sowing measures have a significant impact on the 0-10 cm soil available P,while the year has a significant effect on the soil available P in each layer of mixed grassland.Short-term fenced measures have a significant impact on the soil SOM,TN and TP of the slightly degraded alpine meadow soil.Compared with moderately degraded grasslands,reseeding measures have a significant impact on 0-20 cm soil SOM and TN,and have a significant impact on 0-30 cm soil layer TP;compared with heavily degraded meadow,single sowing and mixed sowing have no significant impact on the SOM and TN of 0-30 cm soil,but single and mixed sowing measures have a significant impact on TP of 0-30 cm soil.Reseeding,single and mixed sowing measures have a significant impact on the SOM and TN of the 10-20 cm soil layer with the increase of years.With the increase of years,each improvement measure has a significant effect on the TP of the 0-30 cm soil layer.(3)The aboveground biomass,species richness and plant diversity respectively were significantly positive correlated with soil SOM and TN,and negatively correlated with soil p H in fenced measures.In reseeding measures,aboveground biomass,species richness and plant diversity respectively were positively correlated with soil p H,but had not significant negative correlated with soil chemical nutrients.In single-sowing measures,aboveground biomass of grassland was positively correlated with soil total phosphorus,but species richness and plant diversity were negatively correlated with soil total phosphorus.In mixed-sowing measures,aboveground biomass was negatively correlated with soil organic matter and soil total nitrogen,species richness and plant diversity were positively correlated with soil organic matter and soil total nitrogen content.Aboveground biomass was positively correlated with soil moisture and soil available phosphorus,and species richness was negatively correlated with soil moisture and soil total phosphorus,plant diversity was significantly negative correlated with soil moisture and soil available phosphorus.