黄土丘陵区人工灌木林土壤酶特征

 采用时空互代法,以侵蚀环境下黄土丘陵区不同林龄的人工灌木林为研究对象,选取坡耕地和天然次生侧柏林为对照,分析了植被恢复过程中土壤酶的演变特征,并在此基础上提出了土壤酶综合评价指数,分析了其变化过程。结果表明:侵蚀环境下的坡耕地改造为灌木林后,脲酶、蔗糖酶、磷酸酶、纤维素酶、过氧化氢酶活性显著增加,并随种植年限增长逐渐升高,相同林龄的沙棘林酶活性高于柠条林;多酚氧化酶活性显著降低;淀粉酶活性变化规律不明显。相关性分析表明:除淀粉酶、脲酶外,蔗糖酶、磷酸酶、过氧化氢酶、纤维素酶相互之间呈显著正相关(P<0.05),与多酚氧化酶活性呈显著负相关;蔗糖酶、磷酸酶、过氧化氢酶、纤维素酶、多酚氧化酶和土壤有机质、全氮、碱解氮等主要养分因子的相关性显著。坡耕地由于人为活动干扰,土壤酶指数较低,改造为灌木林后随种植年限的延长显著增加,但是仍显著低于该地区植被破坏前顶级群落(天然次生侧柏林)。土壤酶指数可以表征各种酶活性大小的综合作用,能够全面客观地反映生态过程中土壤酶活性的演变过程。

Soil enzyme activities of shrub plantation in Loess Hilly Region

In order to reveal changes of soil enzyme activity after revegetation in Loess Plateau,shrub plantation at different ages on Loess Hilly Region was chosen,slope cropland and Platycladus orientailis L.stand were selected as control at the same time.In addition,soil enzymes index was also put forward.The results showed that after revegetation,soil urease,phosphatases,saccharase,cellulase and catalase,respectively increased compared to the slope cropland.Enzyme activity in Hippophae rhamnoides Linn.stand is higher than that in Caragana korshinskii Kom stand at the same ages.Soil polyphenol oxidase decreased with years and amylase did not change significantly.The relationships analysis showed that except urease and amylase,significantly positive relationship were observed among phosphatase,saccharase,cellulase,catalase but negative with polyphenol oxidase,which were also significantly correlated with soil fertility factors such as organic matter,total nitrogen and available nitrogen.It can be concluded that poor soil enzyme activity of slope cropland under erosive environment owing to human cultivation activities was improved greatly after plantation,but still lower than that of Platycladus orientailis L.stand,the climax community before vegetation destruction.Soil enzyme index can be used as biological indicators for assessing soil quality.