经营模式对马尾松近熟林土壤理化性质和化学计量比的影响

Effects of management patterns on soil physicochemical properties and ecological stoichiometric ratio in Pinus massoniana near-mature forest

在25年生马尾松(Pinus massoniana)人工纯林中,设置马尾松特大径材培育(PTD)、皆伐后连栽马尾松纯林(PM)、皆伐后营造红椎纯林(CH)、皆伐后营造马尾松×红椎同龄混交林(PCT)及间伐后林下补植红椎改造成马尾松×红椎异龄混交林(PCY)5种经营模式的试验,研究不同经营模式对土壤理化性质和生态化学计量比的影响。结果表明:经营模式显著影响除容重、全钾以外的土壤理化性质以及C∶N、N∶P。其中:土壤总孔隙度以CH、PCT最高,显著高于PTD和PCY;土壤p H值以CH最高。土壤总有机碳、全氮、速效氮、全磷以PCY和PTD最高,速效磷以CH和PCT最高,速效钾则以PCT显著高于其他处理。土壤C∶N以PM和PCT显著高于其他处理;土壤N∶P以PCY最高,但仅略高于PTD和CH,显著高于PM和PCT;而C∶P处理间差异不显著。综合分析表明,红椎纯林和马尾松×红椎异龄混交林两种模式的土壤质量略高于特大径材培育和马尾松×红椎同龄混交模式,且显著高于马尾松连栽模式。应特别注意马尾松林经营期的延长而造成的土壤磷对植物生长的限制。

In a 25-year-old Pinus massoniana plantation,five forest management patterns were set up to examine the effects of forest management pattern on soil physicochemical properties and ecological stoichiometric ratio.The management patterns included:(1)super-large diameter timber cultivation(PTD),(2)continuously planting P.massoniana after clear-cutting(PM),(3)planting Castanopsis hystrix after clear-cutting(CH),(4)planting P.massoniana×C.hystrix same-aged mixed forest after clear-cutting(PCT),and(5)planting P.massoniana×C.hystrix different-aged mixed forest after thinning(PCY).Results showed that forest management pattern significantly affected soil C∶N and N∶P and soil physicochemical characteristics except for soil bulk density and total potassium.Soil total porosity in CH and PCT was significantly higher than that in PTD and PCY.Soil pH was the highest in CH.The contents of soil total carbon,total nitrogen,available nitrogen,and total phosphorus were higher in PCY and PTD than in other forest management patterns,whereas the content of soil available phosphorus in CH and PCT and available potassium in PCT were higher than in other patterns.Soil C∶N was higher in PM and PCT,whereas soil N∶P in PCY was slightly higher than in PTD and CH but significantly higher than in PM and PCT.There was no significant difference of C∶P among different patterns.Our results indicated that soil quality of C.hystrix pure forest and P.massoniana×C.hystrix different-aged mixed forest was slightly higher than that of the patterns of super-large diameter timber cultivation and P.massoniana×C.hystrix same-aged mixed forest,but significantly higher than that of continuously planting P.massoniana.We should pay attention to the limitation of soil phosphorus availability on plant growth resulted from the extended rotation periods of P.massoniana stands.