气候和林分类型对土壤团聚体有机碳的影响

该研究选择我国分布于亚热带、暖温带和寒温带的三个样点8种林分(包括阔叶林、混交林和针叶林)下表层0~20 cm的土壤为研究对象,利用干筛法进行大团聚体和微团聚体分级,测定了各团聚体组分的有机碳量和有机碳百分比,并分析他们与气候、植被和土壤环境变量之间的关系。结果表明:土壤大团聚体和微团聚体有机碳量都受到气候的显著影响,表现为土壤大团聚体和微团聚体有机碳量随年均温的增高而降低,经分析这与低温抑制土壤微生物分解活动有关。土壤团聚体有机碳百分比受到林分类型的影响显著,表现为阔叶林土壤团聚体有机碳百分比高于针叶林,这与林分凋落物的质量有关。此外,土壤pH值和土壤质地也影响土壤团聚体有机碳百分比。这表明气温上升和人为干扰导致的林分类型改变都可能引起土壤团聚体有机碳的下降,加剧气候变化。该研究结果有助于了解土壤团聚体有机碳的变异规律,为预测全球变化下土壤有机碳响应提供数据支持。

Effects of climate and forest types on soil aggregation organic carbon

Study on effects of climate and forest types on soil organic carbon(SOC)in aggregation would attribute much to a better understanding of the variation pattern of soil aggregation organic carbon(OC), and provide researchers with data support for better predicting SOC response to global climate change. We sampled 0-20 cm surface soil layers from eight forests(including broad-leaved, mingled and coniferous forests)in three climate zones, subtropical, warm temperate and cool temperate zone. We also classified macro-aggregation and micro-aggregation with dry sieve method, measured their OC contents and percentages, and analyzed the relationship between aggregation OC and environmental variables. The results showed that both macro-aggregation and micro-aggregation OC contents were significantly affected by climate, and the OC contents of both macro-aggregation and micro-aggregation decreased with the increasing mean annual temperature(MAT). We suggested that this results were caused by the inhibited microbial decomposition activity by the low temperature in the higher latitude area. Aggregation OC percentage was significantly affected by forest types: higher in broad-leaved forests and lower in coniferous forests, resulting from different litter qualities and quantities between various forest types. In addition, soil pH and texture could also affect soil aggregation OC. The aforementioned results indicated that temperature rise and forest structure variation by human disturbance might cause soil aggregation OC content decrease, and lead exacerbate global climate change.