桂林岩溶石山檵木群落不同恢复阶段凋落物层酶对凋落物分解的影响

Effects of litter layer enzyme on litter decomposition of Loropetalum chinense communities at different restoration stages in karst hills of Guilin

关键词:  檵木群落, 凋落物分解, 凋落物层, 酶活性, 桂林岩溶石山

Key words:  Loropetalum chinense communities, litter decomposition, litter layer, enzyme activity, karst hills of Guilin

摘要:

该文选取桂林岩溶石山檵木群落不同恢复阶段(灌木阶段、乔灌阶段和小乔林阶段)作为研究对象,探究凋落物层酶对凋落物分解速率的影响。结果表明:不同恢复阶段凋落物经1 a分解后,凋落物剩余率分别为灌木阶段(59.58%)、乔灌阶段(61.79%)和小乔林阶段(62.02%)。不同恢复阶段凋落物分解速率随演替的进行而减小。3个不同恢复阶段凋落物层多酚氧化酶、脲酶、蔗糖酶活性均在12月份最低,多酚氧化酶活性均在3月份最高,脲酶和蔗糖酶活性均在6月份最高。3个恢复阶段纤维素酶活性变化规律趋势一致,均在6月份酶活性最高,灌木阶段纤维素酶活性在3月份最低,乔灌阶段和小乔林阶段纤维素酶活性均在9月份最低。3个不同恢复阶段的凋落物层酶活性在不同时期均表现为蔗糖酶>脲酶>纤维素酶>多酚氧化酶。不同恢复阶段凋落物层酶活性对凋落物分解速率影响不同。灌木阶段凋落物层蔗糖酶活性与分解速率呈显著正相关(P < 0.05),乔灌阶段脲酶活性与分解速率呈显著正相关(P < 0.05),小乔林阶段各酶活性与分解速率相关不显著。蔗糖酶、脲酶和多酚氧化酶是影响灌木阶段凋落物分解速率的重要因素,脲酶、纤维素酶和多酚氧化酶是影响乔灌和小乔林阶段分解速率的重要因素。

Abstract:

To explore the impact of litter enzyme on litter decomposition rate at different restoration stages, the Loropetalum chinense(shrub stage, shrub to tree stage and small tree stage)communities were selected as the research objects in karst hills of Guilin. The results showed that after one year of decomposition, the dry mass remaining in three different restoration stages of L. chinense communities from low to high was shrub stage(59.58%), shrub to tree stage(61.79%), small tree stage(62.02%). The decomposition rate of litter at different restoration stages of L. chinense communities decreased with the succession of vegetation restoration. The litter layer enzyme activity of polyphenol oxidase, urease and sucrase at three different restoration stages were the lowest in December and the enzyme activity of polyphenol oxidase was the highest in March. The enzyme activity of urease and sucrase were the highest in June. The change trends of cellulase activities at three different restoration stages were consistent, with the highest enzyme activity in June. The cellulase activity was the lowest at shrub stage in March, and the cellulase activity was the lowest at shrub stage and small tree stage in September. The enzyme activity order of litter layer at three different restoration stages of L. chinense communities in different periods was sucrase > urease > cellulase > polyphenol oxidase. The litter enzyme activities at different restoration stages of L. chinense communities played different roles in litter decomposition rate. Litter decomposition rate was positively related to the litter layer enzyme activity of sucrase (P < 0.05)at shrub stage. There was significant correlation between litter decomposition rate and the litter layer enzyme activity of urease(P < 0.05)at shrub to tree stage. There was not significant correlation between the litter decomposition rate and the litter layer enzyme activity at small tree stage. Sucrase, urease and polyphenol oxidase were important factors affect litter decomposition at shrub stage. All these indicate that urease, cellulase and polyphenol oxidase are the important factors that affect the rate of decomposition of shrub to tree stage and small tree stage.