Effects of microtopography on enzyme activities and ecological stoichiometry in an alpine meadow on the Qinghai-Tibet Plateau
The ecological stoichiometric characteristics of soil and enzymes are important in alpine meadows.This study focused on the critical parameters of soil,extracellular enzymes,and vegetation to explore the effects of microtopography shady slope,sunny slope,and ravine)on soil and extracellular enzyme stoichiometry,along with the influencing factors in a small-scale alpine meadow on the Qinghai-Tibet Plateau.We determined the levels and activities of β-1,4-glucosidase(BG),cellulose disaccharide hydrolase(CBH),β-1,4-acetyl-glucosaminidase(NAG),leucine aminopeptidase(LAP)and acid,phosphatase(AP)in the soil.Next,the ecological stoichiometric ratios of the soil and extracellular enzymes were calculated.Additionally,we investigated plant community characteristics and below-ground biomass to calculate the vegetation species diversity index,as well as measured soil pH and water content(SWC).The results showed that:(1)Microtopography had significant effects on soil total phosphorus,acid phosphatase,and pH(P＜0.05),but did not affect the other soil indicators(P＞0.05).(2)Microtopography had a significant effect on plant community composition and diversity,with the highest plant diversity on sunny slopes and the lowest on shady slopes(P＜0.001).(3)Variations in vegetation diversity caused by microtopography were essential factors affecting soil C∶N,and plant species presented a significantly negative effect on soil C∶N(P＜0.01).(4)A significant positive correlation was found between root biomass and soil C∶N ratio,indicating that vegetation productivity is a key factor leading to soil C∶N change.(5)Vegetation factors and soil pH and soil total phosphorus content jointly regulate soil enzyme activities and the ecological stoichiometry of soil enzymes in the microtopography.Generally,the variations in plant community characteristics and soil properties caused by microtopography significantly affected soil enzyme activities and soil-enzyme ecological stoichiometry in alpine meadows.The results of this study provide the necessary theoretical support for clarifying the cycling processes of key elements in the alpine meadows of the Tibetan Plateau in the context of future climate change.
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