大兴安岭泥炭地不同菌根类型木本植物叶片凋落物分解及其温度敏感性差异

以我国大兴安岭多年冻土区泥炭地常见的3种外生菌根木本植物(细叶沼柳Salix rosmarinifolia、白桦Betula platyphylla和柴桦B.fruticosa)和4种欧石楠菌根木本植物(笃斯越桔Vaccinium uliginosum、狭叶杜香Ledum palustre、甸杜Chamaedaphne calyculata和小叶杜鹃Rhododendron parrifolum)为研究对象,通过315天培养试验测定10和20℃叶片凋落物分解过程中的碳(C)累积矿化量和重量损失,并分析其温度敏感性。结果表明:外生菌根植物叶片凋落物的C矿化量和重量损失在10和20℃均高于欧石楠菌根植物;外生菌根植物凋落物分解过程中C矿化量的温度敏感性系数高于欧石楠菌根植物,但重量损失的温度敏感性系数低于欧石楠菌根植物;在每一培养温度下,C矿化量和重量损失均与凋落物全氮(N)和全磷(P)浓度呈正相关,与C/N和C/P呈负相关;尽管C矿化量的温度敏感性系数与凋落物初始化学组成无显著相关性,但重量损失的温度敏感性系数与凋落物全N和全P浓度呈负相关,与C/N和C/P呈正相关。本研究结果为认识和预测气候变暖及其引起的物种组成变化对北方泥炭地植物凋落物分解的影响提供理论依据。

Differences in leaf litter decomposition and its temperature sensitivity among woody species with different mycorrhizal associations in a peatland in the Daxing’an Mountain.

Using leaf litters of three ectomycorrhizal woody species(Salix rosmarinifolia,Betula platyphylla,and B.fruticosa)and four ericoid mycorrhizal woody species(Vaccinium uliginosum,Ledum palustre,Chamaedaphne calyculata,and Rhododendron parrifolum)from a permafrost peatland in the Daxing’an Mountain of China,we compared the differences in carbon(C)mineralization and mass loss during litter decomposition at 10 and 20℃,and temperature sensitivity of C mineralization and mass loss between ectomycorrhizal and ericoid mycorrhizal woody species in a 315-day laboratory incubation experiment.We found that ectomycorrhizal species had greater C mineralization and mass loss than ericoid mycorrhizal species during litter decomposition at both 10 and 20℃.Compared with ericoid mycorrhizal species,litters of ectomycorrhizal species had higher temperature sensitivity of C mineralization,but lower temperature sensitivity of mass loss.In addition,C mineralization and mass loss correlated positively with litter nitrogen(N)and phosphorus(P)concentrations,but negatively with C∶N and C∶P ratios.Temperature sensitivity of mass loss correlated negatively with litter N and P concentrations,but positively with C∶N and C∶P ratios.However,there was no significant relationship between temperature sensitivity of C mineralization and litter initial chemical properties.Our results will help understand and predict the effects of climate warming and associated shifts in species composition on litter decomposition in boreal peatlands.