青海省森林土壤有机碳氮储量及其垂直分布特征

森林土壤在调节森林生态系统碳、氮循环和减缓全球气候变化中起着关键的作用。但是,由于林型、林龄以及环境因子(海拔)的差异,至今对于森林土壤碳、氮储量的估算依然存在极大的不确定性。因此,利用森林土壤实测数据估算了青海森林土壤有机碳、氮密度和碳、氮储量,分析了土壤有机碳、氮密度的垂直分布格局。结果表明:1)土壤有机碳密度随海拔的增加呈单峰曲线变化,在海拔3100—3400 m达到最大34.33 kg/m~2;氮密度随海拔的增加而增加,范围为1.39—2.93 kg/m~2。2)在0—30 cm土层,土壤有机碳、氮密度均随土层的增加而降低,范围分别为3.84—4.63 kg/m~2、0.22—0.27 kg/m~2。3)青海省森林土壤碳储量为1098.70 Tg,氮储量为61.78 Tg。4)海拔与氮含量和密度之间存在极显著正相关关系(P0.01,P0.01)。土层深度与有机碳含量存在极显著负相关关系(P0.01);与有机碳密度、氮密度存在极显著正相关关系(P0.01,P0.01)。说明海拔和土层是影响青海省森林土壤有机碳、氮分布的关键因子。

Forest soil organic carbon and nitrogen storage and characteristics of vertical distribution in Qinghai Province

Forest soil plays a key role in regulating carbon and nitrogen cycle and mitigating the effects of global climate change. However, due to the differences in forest type, age, and altitude, there is still a great uncertainty about the estimation of forest soil carbon and nitrogen reserves. In this study, we used the measured data from Qinghai forest soil to estimate the density of organic carbon, nitrogen, and the storage of organic carbon and nitrogen pool, and their vertical distribution patterns. The results indicated that 1) the soil organic carbon density showed a unimodal change with the altitude with a maximum (34.33 kg/m²) at the altitude of 3100-3400 m; the nitrogen density increased with the increase in altitude, and ranged from 1.39 to 2.93 kg/m². 2) In the 0-30 cm soil layer, the soil organic carbon and nitrogen density decreased with an increase in the soil depth, and their ranges were from 3.84 to 4.63 kg/m² and 0.22 to 0.27 kg/m², respectively. 3) Total soil carbon storage was 1098.70 Tg, and the total nitrogen storage was 61.78 Tg in the forest soil of Qinghai province at 0-100 cm soil layer. 4) There was a positive correlation between the altitude and nitrogen content, as well as between the altitude and nitrogen density (P < 0.01). There was a negative correlation between the soil depth and organic carbon content, and a positive correlation between the soil depth and organic carbon density and nitrogen density (P < 0.01). These results indicate that the altitude and soil depth are key factors influencing the distribution of organic carbon and nitrogen in forest soils in Qinghai Province.