黄土丘陵区4种典型植被对土壤养分及酶活性的影响

土壤酶积极参与土壤系统的生物化学过程,是联系"植物-土壤酶-土壤养分"的关键纽带。为探讨植被类型对黄土高原丘陵区土壤养分及酶活性的影响,以黄土丘陵区4种典型植被(荒草地、文冠果林地、柠条灌丛、沙棘林地)为研究对象,通过采集0—10,10—20,20—40 cm层土壤样品,测定和分析土壤养分(碳、氮、磷)及土壤酶活性(蔗糖酶、脲酶、过氧化氢酶、淀粉酶)的变化特征。结果表明:文冠果林地0—40 cm层土壤有机碳和全氮含量比荒草地、柠条灌丛、沙棘林地高出了19.42%和35.15%、82.98%和40.49%、67.27%和24.12%,土壤全磷含量最大值(沙棘林地)比最小值(柠条灌丛)高出了12.45%。随着土层深度的增加,土壤有机碳、全氮、全磷含量在柠条灌丛中呈现"升-降"的变化规律,在其他3种植被类型中均呈逐渐减小的趋势。4种植被类型下土壤淀粉酶、脲酶和蔗糖酶活性差异显著(P0.05),土壤酶活性随着土层深度的增加逐渐减弱。其中土壤淀粉酶最大值出现在荒草地,脲酶和蔗糖酶活性最大值为文冠果林地,3种酶的最小值均出现在柠条灌丛。相关分析表明,土壤有机碳与全氮、蔗糖酶、脲酶极显著正相关(P0.01)。土壤全氮与脲酶在0.01水平上极显著正相关,与全磷、蔗糖酶在0.05水平上显著正相关。土壤全磷与硝态氮呈极显著的负相关(P0.01),与蔗糖酶呈极显著的正相关(P0.01),与淀粉酶呈显著正相关(P0.05)。因此,植被类型是影响黄土高原土壤酶活性和养分变化的重要因素。

Effects of Four Typical Vegetations on Soil Nutrient and Enzymes Activities in Loess Hilly Region

Soil enzymes actively participate in the biochemical processes of soil systems and are the key link to the "plant-soil enzymes-soil nutrients". In order to investigate the effects of vegetation types on soil nutrient and enzymes activities in the hilly region of the Loess Plateau, four typical vegetations (grassland, Xanthoceras sorbifolia, Caragana korshinskii shrub, and Hippophae rhamnoides) in the loess hilly region were studied. Soil samples of 0-10, 10-20 and 20-40 cm layers were sampled to determine and analyze the changes of soil nutrient (carbon, nitrogen, phosphorus) and soil enzymes activities (sucrose, urease, catalase, amylase). The results showed that the soil organic carbon and total nitrogen contents in the 0-40 cm layer of the Xanthoceras sorbifolia were 19.42% and 35.15%, 82.98% and 40.49%, 67.27% and 24.12% higher than those of the grassland, Caragana korshinskii shrub, and Hippophae rhamnoides respectively. With the increase of soil depth, the contents of soil organic carbon, total nitrogen and total phosphorus showed a "increase first and then decrease" change in Caragana korshinskii shrub, but gradually decreased under the other three vegetation types. The soil amylase, urease and sucrase activities were significantly different among the four vegetation types (P<0.05), and the soil enzymes activities decreased with the increase of soil depth. The maximum value of soil amylase was found in the grassland, the maximum values of urease and sucrase activities were in Xanthoceras sorbifolia, and the lowest values of the three enzymes were found in Caragana korshinskii shrub. Correlation analysis showed that soil organic carbon contents were significantly positively correlated with total nitrogen, sucrase and urease activities (P<0.01). There was a significant positive correlation between soil total nitrogen contents and urease activities at 0.01 level, and a significant positive correlation between total phosphorus contents and sucrose activities at 0.05 level. Soil total phosphorus contents were negatively correlated with nitrate nitrogen contents (P<0.01), positively correlated with sucrose (P<0.01) and amylase activities (P<0.05). Therefore, vegetation type is an important factor affecting soil enzymes activities and nutrient changes in the Loess Plateau.