Vegetation degradation impacts soil nutrients and enzyme activities in wet meadow on the Qinghai-Tibet Plateau

Abstract

Vegetation degradation, due to climate change and human activities, changes the biomass, vegetation species composition, and soil nutrient input sources and thus affects soil nutrient cycling and enzyme activities. However, few studies have focused on the responses of soil nutrients and enzymes to vegetation degradation in high-altitude wet meadows. In this study, we examined the effects of vegetation degradation on soil nutrients (soil organic carbon, SOC; total nitrogen, TN; total phosphorus, TP) and enzyme activities (i.e., urease, catalase, amylase) in an alpine meadow in the eastern margin of the Qinghai-Tibet Plateau. Four different levels of degradation were defined in terms of vegetation density and composition: primary wet meadow (CK), lightly degraded (LD), moderately degraded (MD), and heavily degraded (HD). Soil samples were collected at depth intervals of 0–10, 10–20, 20–40, 40–60, 60–80, and 80–100 cm to determine soil nutrient levels and enzyme activities. The results showed that SOC, TN, catalase and amylase significantly decreased with degradation level, while TP and urease increased with degradation level (P < 0.05). Soil nutrient and enzyme activity significantly decreased with soil depth (P < 0.05), and the soil nutrient and enzyme activity exhibited obvious "surface aggregation". The activities of soil urease and catalase were strongest in spring and weakest in winter. The content of TN in spring, summer, and autumn was significantly higher than observed in winter (P < 0.05). The soil TP content increased in winter. Soil amylase activity was significantly higher in summerm than in spring, autumn, and winter (P < 0.05). TP was the main limiting factor for plant growth in the Gahai wet meadow. Values of SOC and TN were positively and significantly correlated with amylase and catalase (P < 0.05), but negatively correlated with urease (P < 0.05). These results suggest the significant role that vegetation degradation and seasonal freeze–thaw cycle play in regulating enzyme activities and nutrient availability in wet meadow soil.

Effects of conservation tillage strategies on soil physicochemical indicators and N2O emission under spring wheat monocropping system conditions

“…Soil core sampler with a diameter of 5 cm was used to collect soil samples at 0–10 cm soil layer. Debris were removed and stored in a ziplock bag and placed in a sample box with an ice bag for cooling during transportation 20 . These samples were taken back to the laboratory for the determination of soil indicators.…”

Effects of Different Land Use Types and Soil Depths on Soil Mineral Elements, Soil Enzyme Activity, and Fungal Community in Karst Area of Southwest China

“…Soil enzymes have a high catalytic capacity and take part in organic matter decomposition and cycling of nutrient in ecosystem [ 10 ]. Soil nutrients, microorganisms, vegetation types and management measures affect soil enzyme activities in different degrees [ 11 , 12 , 13 ]. More importantly, soil enzyme activity can represent the rate of nutrient uptake by microorganisms and plants.…”

The role of plants and soil properties in the enzyme activities of substrates on hard coal mine spoil heaps

“…The close relationship of plant community composition, including species richness and functional group assembly, influences soil functions such as soil microbial biomass and activity has been conducted by many researchers 17 – 19 . Therefore, the presence of plants seems to have a key impact on the enzymatic activity of the soil, because the chemical composition of plant residues and thus the soil nutrient status affect microbial activity and microbial community structure 20 . For all of these reasons soil enzymes are used as an index of soil microbial activity and can react quickly to changes in environmental conditions 21 – 23 , microbial community structure 24 and vegetation diversity 25 , 26 .…”