火烧对马尾松林土壤酶活性和有机碳组分的影响

Effects of fire on soil enzyme activities and organic carbon fractions in Pinus massoniana forest

土壤酶参与土壤有机质矿化过程,林火能通过改变土壤中微生物的群落结构等来改变土壤酶的活性,进而影响土壤有机碳的动态过程。土壤有机碳库是陆地碳库的重要组成部分,火烧会使土壤有机碳组分发生变化,研究火烧后土壤有机碳组分的变化对于土壤有机碳库的管理具有重要意义。以我国中亚热带典型马尾松人工林火烧迹地为研究对象,通过对比研究,探讨了火烧对土壤酶活性和土壤有机碳组分的影响以及两者之间的关系。结果表明:(1)与对照相比,火烧后一年0—10 cm土层土壤p H值明显升高(P<0.05),土壤总碳含量显著降低(P<0.05),土壤全氮含量平均降低17.5%(P>0.05)。0—10 cm土层和10—20 cm土层土壤含水量均显著低于对照(P<0.05)。(2)相比对照,土壤β-葡萄糖苷酶活性在0—10 cm土层显著降低(P<0.05),土壤酚氧化物酶活性和过氧化物酶活性显著升高(P<0.05)。(3)火烧后一年0—10 cm土层土壤微生物量碳、土壤颗粒性有机碳、土壤易氧化碳含量比对照分别降低26.4%、30.9%和2.69%,但无显著差异,土壤溶解性有机碳含量则显著降低(P<0.05);两个土层土壤不稳定有机碳含量和粘粒有机碳含量变化不显著。

Soil enzymes are involved in the mineralization of soil organic matter （SOM）. Forest fire changes soil enzyme activities by changing microbial community structure and thus affects the dynamic processes of soil organic carbon （SOC）. The SOC pool is an important component of the terrestrial carbon pool, and forest fire causes changes in SOC fractions. The effects of fire on soil enzyme activities and SOC fractions were assessed using a comparative study on a burned area of typical Pinus massoniana plantation in subtropical China. The results showed that： （1） Compared with the control, soil pH at depth of 0--10 cm increased dramatically one year after the fire （P 〈 0.05 ）. Conversely, total soil carbon （TC） concentration decreased by 29.1% （P〈0.05） , the average of soil total nitrogen （TN） concentration decreased by 17.5% （P〉0.05）. Soil moisture content at 0--10 cm and 10--20 cm were both significantly lower than that of control （P〈0.05）. （2） Compared with the control, the activity of soil ^-glucosidase decreased at depth of 0--10 cm （P〈0.05） ; however, soil phenyl oxygenase and peroxidase activities significantly increased （ P〈0.05 ）. （ 3 ） One year after the fire, soil microbial biomass carbon, soil particulate organic carbon, and soil readily oxidized carbon concentration at depth of 0--10 cm decreased by 26.4%, 30.9%, and 2.69% （ P 〉 0. 05 ） , respectively, but soil dissolved organic carbon concentration decreased by 19.2% significantly （P〈0.05）. Both layers of soil clay organic carbon concentration tended to decrease （P〉 0.05）.