毛竹入侵常绿阔叶林对土壤活性有机碳氮的动态影响

Effects of moso bamboo invasion on soil active organic carbon and nitrogen in a evergreen broad-leaved forest in subtropical China

在中国南方,毛竹向周边森林入侵已是较为突出的生态学现象。毛竹与周围森林原有物种的性状特征存在差异,将不可避免地改变原有森林的土壤养分循环。为了揭示毛竹入侵对土壤活性有机碳、氮的影响,在毛竹入侵样带上,选择常绿阔叶林、竹阔混交林、毛竹纯林为研究对象,以土壤水溶性有机碳、氮含量和微生物生物量碳、氮为指标,分析毛竹入侵对常绿阔叶林土壤活性有机碳、氮含量的影响及其季节规律。结果表明:3种林分之间年平均水溶性有机碳、氮含量和微生物生物量碳、氮差异显著,总体表现为阔叶林>混交林>毛竹林(P<0.05);3种林分的水溶性有机碳、氮含量和微生物生物量碳、氮均有相似的季节变化,其中土壤水溶性有机碳含量与微生物生物量碳最高值出现在秋季,最低值出现在夏季,且其含量在大多数季节3种林分差异与年平均含量差异一致,均表现为阔叶林>混交林>毛竹林(P<0.05);皮尔森相关分析显示,土壤活性有机碳、氮各组分间存在着显著相关性(P<0.01);毛竹入侵常绿阔叶林后通过降低土壤中活性有机碳、氮含量与微生物生物量碳、氮,进而降低原有土壤养分,最终改变原有的土壤有机碳库与氮库的结构。研究结果可以为合理管控抛荒毛竹林提供启发,为毛竹入侵对土壤性质的影响研究提供基础数据。

Moso bamboo has expanded its range by invading the broad-leaved forests of southern China.Its invasion can alter soil carbon and nutrient cycling in invaded habitat because plant traits of moso bamboo differ from native species.Here,we examined the effects of moso bamboo invasion on soil active organic carbon and nitrogen along a transect of evergreen broad-leaved forest,mixed bamboo and broad-leaved forest,and pure moso bamboo forest.The concentrations of water-soluble organic carbon and nitrogen in soils and microbial biomass carbon and nitrogen were measured to examine the effects of moso bamboo invasion on soil active organic carbon and nitrogen in evergreen broad-leaved forest and the seasonality of such effects.The mean annual concentrations of water-soluble organic carbon and nitrogen and microbial biomass carbon and nitrogen were significantly different among forest types.The overall performance was in the order of broadleaved forest>mixed forest>moso bamboo forest(P<0.05),which was generally consistent across seasons.Water-soluble organic carbon and nitrogen contents and microbial biomass carbon and nitrogen of the three habitats experienced paralleled seasonal changes.Soil water-soluble organic carbon content and microbial carbon were the highest in autumn and the lowest in summer.There was a significant positive relationship between the contents of soil active organic carbon and nitrogen(P<0.01).Moso bamboo invasion into evergreen broad-leaved forests reduced soil active organic carbon and nitrogen contents,which decreased the contents of original soil nutrients and changed the structure of the original soil organic carbon and nitrogen pools.Our results provide insight into the management of abandoned moso bamboo stands and basic data for future study of the effects of moso bamboo invasion on soil properties.