不同海拔对福建戴云山黄山松林土壤微生物生物量和土壤酶活性的影响

Effects of different altitudes on soil microbial biomass and enzyme activities in Pinus taiwanensis forests on Daiyun Mountain, Fujian Province

温度、水分等多种环境因子随海拔梯度发生变化,会直接或间接影响土壤微生物生物量、群落结构以及土壤酶活性。然而关于中亚热带地区山地森林生态系统土壤酶活性变化响应的研究还是相对匮乏。戴云山山脉是中国最大的黄山松种质基因基地,本研究以中亚热带戴云山1300 m (L)、1450 m(M)、1600 m(H)的黄山松(Pinus taiwanensis)为研究对象,探究不同海拔下土壤微生物生物量和土壤酶活性如何变化及驱动土壤酶活性变化的主要的环境因子。结果表明:海拔梯度对淀积层(B)土壤的酶活性影响整体较小,在淋溶层(A)土壤中,随海拔升高,纤维素水解酶(β-葡糖苷酶(βG)、纤维素水解酶(CBH))显著降低,因此使土壤可溶性碳(DOC)和微生物生物量碳(MBC)随海拔升高有下降趋势。尽管酸性磷酸酶活性(ACP)随海拔升高显著增加,然而有效磷(AP)无显著变化。此外随海拔升高,微生物生物量氮(MBN)、微生物生物量磷(MBP)显著降低。冗余分析(RDA)结果发现,MBP和碳/氮比(C/N)是影响A层中土壤酶活性变化最重要的因子,而在B层中,土壤含水量(WC)和MBP对土壤酶活性起主要作用。研究表明,磷限制的亚热带地区,无机磷很容易被铁铝固定,MBP可以对土壤中的有效磷进行补充,成为影响本地区酶活性的主要因素。随海拔海拔降低,土壤有机碳、氮分解相关酶活性较高,从而加速了土壤碳、氮周转。因此,探究不同海拔梯度酶活性变化为预测中亚热带亚山地森林生态系统土壤碳、氮、磷养分循环提供了重要的理论依据,也为戴云山自然保护区黄山松林管理提供一定的科学依据。

Temperature,moisture,and other environmental factors change with altitude,which directly or indirectly can affect soil microbial biomass,community structure,and soil enzyme activity.However,research on the response of soil enzyme activities in the alpine forest ecosystems of the subtropical regions is relatively limited.Daiyun Mountain is the largest Pinus taiwanensis germplasm resource in China.In the present study,Pinus taiwanensis at altitudes of 1300 m(L),1450 m(M),and 1600 m(H)in the mid-subtropical Daiyun Mountain was used to study changes in soil microbial biomass and soil enzyme activities at different altitudes.The results showed that the effect of different altitudes on enzyme activity was generally weak in the B horizon,and cellulolytic enzymes activities(e.g.,β-glucosidase(βG)and cellulolytic enzyme(CBH))decreased significantly with increasing altitude in the A horizon,thus resulting in a decrease in soil soluble carbon(DOC)and microbial biomass carbon(MBC)with increasing altitudes.Although acid phosphatase activity(ACP)increased significantly with altitudes,there was no significant change in available phosphorus(AP)levels.In addition,microbial biomass nitrogen(MBN)and microbial biomass phosphorus(MBP)decreased significantly with increasing altitude.Redundancy analysis(RDA)showed that MBP and carbon/nitrogen(C/N)ratio were the most important factors determining soil enzyme activity in the A horizon,whereas soil water content(WC)and MBP levels played a major role in determining soil enzyme activity in the B horizon.This study showed that.in the phosphorus-limited subtropical region,inorganic phosphorus is easily fixed by iron and aluminum.MBP,can supplement available phosphorus in soil and become a major factor affecting enzyme activity in this area.Soil organic carbon and nitrogen decomposition related enzyme activities increased as decreasing altitude,which accelerated the turnover of soil carbon and nitrogen.Therefore,exploration of changes in enzyme activity at different altitudes provides a scientific basis for predicting soil carbon,nitrogen,and phosphorus cycling in mid-subtropical subalpine forest ecosystems,which provides a scientific basis for the management of Pinus taiwanensis forests in Daiyunshan Nature Reserve.