Effects Of Global Change Factors And Living Roots On Root Litter Decomposition In A Tibetan Alpine Meadow

Plant root system is not only the main component of plant biomass,but also an important source of soil organic carbon.On the one hand,the decomposition of root litter affects the flow of carbon by releasing carbon dioxide into the atmosphere.On the other hand,the decomposition of root litter can regulate the cycling of nutrients by releasing nutrients for plants use.Therefore,root decomposition plays an important role in carbon and nutrient dynamics in soil.Root stocking the Qinghai-Tibet Plateau is enormous,representing a huge organic carbon pool.Small changes in soil carbon in the Qinghai-Tibet Plateau can have profound effects on carbon dynamics.In addition,as a biological factor affecting root decomposition,the large alive root system itself affects the decomposition of root litterl As a typical alpine ecosystem,the Qinghai-Tibet Plateau is sensitive and responds quickly to global change factors.However,there are few studies about the effects of global change factors and living roots on decomposition of root litter in ecosystems on the Qinghai-Tibet Plateau.In a field manipulation experiment located at the Research Station of Alpine Meadow and Wetland Ecosystem of Lanzhou university,I carried out a litterbag experiment with the treatments of nitrogen(N)addition(120 kg N per hectare),warming with open top chamber(OTC),precipitation changes(increased by 30%and decreased by 30%,respectively)and litterbag size(1mm and 20μm)to investigate the effects of global change factors and living roots on decomposition of root materials.In addition,I also investigated the effect of soil pH and living roots on root decomposition got through directly manipulating soil pH.The main results are as follows:1.N addition significantly inhibited the loss of mass and carbon in the root litter,and promoted the accumulation of N in root litter.2.Increasing precipitation significantly enhanced the inhibition effect of N addition on the root decomposition.3.The presence of living roots significantly increased N and phosphorus remaining in the root litter.4.Both warming and N addition significantly increased the content of organic N in the soil,but decreased soil temperature.There was a significant negative correlation between soil temperature and N remaining of root litter,regardless of the presence of living roots.5.Decreasing soil pH significantly inhibited root decomposition by influencing root characteristics but not by influencing soil characteristics.In addition,the presence of living roots significantly promoted the litter decomposition.In summary,N inputs,precipitation and soil acidification may exert significant impacts on litter decomposition in the alpine meadow on the Qinghai-Tibet Plateau under the future climate change scenarios.In addition,the large root biomass in the alpine ecosystems can play an important role in influencing nutrient dynamics through mediating the decomposition of root materials.