不同处理采伐剩余物对营造杉木幼林土壤胞外酶活性的影响

土壤酶对森林生态系统生物化学过程有重要作用,能快速反映土壤环境(如养分含量和有效性)的变化。采伐剩余物是林地土壤养分的重要来源,其处理方式会对森林土壤的养分含量和有效性产生影响。为探讨采伐剩余物不同处理方式对杉木幼林土壤酶活性的影响,在福建省三明市格氏栲自然保护区40年生的杉木成熟林采伐迹地上对采伐剩余物进行不同处理(保留RR、火烧RB、去除R)并种植杉木幼林,通过采集0-10,10-20 cm土层土壤,对6种胞外酶活性进行研究。结果表明:(1)采伐剩余物处理4年后,相比保留处理,火烧和清除处理的土壤可溶性有机碳、可溶性有机氮、无机氮、硝态氮含量均显著下降。其中火烧处理下硝态氮下降幅度显著高于清除处理,2个土层下降幅度平均分别为88%和51%;(2)相比保留处理,火烧和清除处理土壤微生物生物量碳和微生物生物量磷含量以及6种土壤酶活性,即酸性磷酸酶、β-葡萄糖苷酶、纤维素水解酶、β-N-乙酰氨基葡萄糖苷酶、过氧化酶、酚氧化酶均明显更低,而且火烧处理两土层微生物生物量碳和微生物生物量磷含量显著低于清除处理;(3)冗余分析表明,0-10 cm土层土壤酶活性与微生物生物量磷、微生物生物量碳含量显著相关,而可溶性有机氮、硝态氮、微生物生物量碳是影响10-20 cm土层土壤酶活性变化的关键因子。保留采伐剩余物有利于提高土壤养分和酶活性,是土壤肥力维持和森林生产力提高的有效经营管理措施。

Effects of Different Harvest Residue Treatments on Soil Extracellular Enzymes Activities in a Young Chinese Fir Plantation

Soil enzyme plays an important role in the biochemical processes of forest ecosystems,which can quickly reflect the changes of soil environment(such as nutrient content and availability).Harvest residue is an important source of forest soil nutrients,and its treatment methods will affect the nutrient content and availability of forest soil.In order to explore the effects of different harvest residue treatments on soil enzymes activities,harvest residue was managed in the following ways,i.e.,residue retained(RR),residue removed(R)and residue burnt(RB)after cutting a 40-year-old mature Chinese fir forest in Sanming City,Fujian,and six soil extracellular enzymes activities in 0-10 and 10-20 cm soil layers were studied.The results showed that:(1)After 4 years of harvest residue treatment,compared with RR treatment,the contents of dissolved organic carbon(DOC),dissolved organic nitrogen(DON),inorganic nitrogen(IN)and NO3--N in RB and R treatments decreased significantly.Further,the decrease of NO3--N content under RB treatment was significantly higher than that of R treatment,decreased by 88%and 51%for 0-10 and 10-20 cm soil layers respectively;(2)Compared with RR treatment,microbial biomass phosphorus(MBP)and carbon(MBC),and six soil enzymes activities,that were acid phosphatase(AP),β-1,4-glucosidase(βG),Cellobiohydrolase(CBH),β-1,4-N-acetylglucosaminidase(NAG),Poly-phenol oxidase(PHO),and Peroxidase(PEO)of RB and R treatments decreased significantly.Also MBC and MBP contents in two soil layers under RB treatment were significantly lower than those of R treatment;(3)Redundancy analysis showed that soil enzymes activities in the 0-10 cm layer were significantly correlated with soil MBP and MBC contents,and DON,NO3--N and MBC were the key factors affecting soil enzyme activities in the 10-20 cm layer.Therefore,the retention of harvest residues is beneficial to the improvement of soil nutrients and enzyme activity,and it is an effective management measure for the maintenance of soil fertility and the improvement of forest productivity.