天山雪岭云杉林土壤有机碳密度空间分异及其与森林发育的关系

Spatial Variation of the Density of SOC of Picea Schrenkiana Forest and Relationships with Forest Development

森林土壤在组分和结构上存在比较明显的空间分异现象是导致森林土壤有机碳库估算存在较大不确定性的主要因素之一,森林发育阶段(林龄)也可能是影响森林土壤有机碳库估算不确定性的重要因素之一。本研究在天山北坡西、中、东三段的云杉林分别按林龄设置系列样地并分层采集土样,探讨了天山北坡雪岭云杉林土壤有机碳密度的空间分异规律,并试图从森林发育的角度分析产生该空间分异规律的原因。研究结果表明:(1)天山雪岭云杉林0-60 cm深度的土壤剖面上平均总土壤有机碳密度为30.77±13.46 kg/m^2,天山西、中、东三段雪岭云杉森林总土壤有机碳密度的分布规律为中部(40.54±11.33 kg/m^2)>西部(29.61±14.94 kg/m^2)>东部(22.16±5.88 kg/m^2),且中部与东、西两部差异显著(p<0.05);(2)在0-60 cm深度的土壤剖面上,西、中、东三段雪岭云杉林不同林龄的土壤有机碳密度均呈随着剖面深度增加而减少的趋势,表层(0-20 cm)土壤有机碳密度占总剖面土壤有机碳64.87%。(3)随着龄林的增长,土壤有机碳密度整体呈现出双峰曲线,不同林龄土壤有机碳密度排序为,过熟林(37.02±17.19 kg/m^2)>中龄林(33.58±14.53 kg/m^2)>近熟林(29.12±15.77 kg/m^2)>成熟林(27.02±7.62 kg/m^2)>幼龄林(27.10±9.81 kg/m^2),各龄林土壤有机碳密度差异不显著。(4)通过多因素方差分析可知,土壤有机碳密度的空间分异主要受到地段和土层条件影响,林龄对土壤有机碳密度的影响不大。本研究可为天山森林土壤有机碳储量的估算提供数据参考,同时为更深入了解天山林区土壤有机碳分布规律及其影响因素提供必要的基础。

There is a distinguish spatial variation in composition and structure of forest soil,which is one of the main factors leading to the uncertainty of estimation of soil organic carbon pools in forest. Additional forest stages may also be one of the important factors affecting the forest soil organic carbon pool estimation uncertainty. Soil samples were collected from a series of plots which set by forest ages of Picea schrenkiana forest on north slope of west,middle and east areas of Tianshan Montains. We tried to discuss the spatial variation of the density of SOC of Picea schrenkiana forest and attempted to analyze the reason why the spatial variation was presented from the perspective of forest development. The results showed that：（ 1） The average total soil organic density of standard profile at the depth 0 to 60 cm in Tianshan forest was 30. 77 ± 13. 46 kg/m^2,and the distribution of the total SOC density of three areas of Tianshan Montains was middle area west area east area. In addition,there was a significant difference between east area and west areas（ p 0. 05）;（ 2） The SOC density at a depth of 0-60 cm standard soil profile mainly presented a decreasing trend with increasing of profile depth. It had obvious surface assembly that the SOC density of surface soil（ 0-20 cm） accounted for 64. 87% of the total profile SOC,and maintained significant difference between surface＇s and SOC of two soil layers（ 20-40 cm,40-60 cm）.（ 3） With a increase of the age plantation,density of SOC presented a bimodal curve as the forest age increased,whose peaks appeared at middle-aged forest and at over-mature forest,the order of SOC density of different age plantation was： over mature（ 37. 02 ± 17. 19 kg/m^2） medium（ 33. 58 ± 14. 53 kg/m^2） near mature（ 29. 12 ± 15. 77 kg/m^2） mature（ 27. 02 ± 7. 62 kg/m^2） juvenile（ 27. 10 ± 9. 81 kg/m^2）,no significant difference among all age plantation SOC. It indicated that SOC reserve of the north of Tianshan Mountains remained stable as a whole. By multi-factor analysis of variance,it showed that the spatial differentiation of SOC density mainly was affected by the location and soil conditions,while the influence of forest age on SOC density was not significant. This research can provide a data reference for the estimation of Tianshan forest SOC reserves,at the same time,provide important theoretical basis for more in-depth understanding of Tianshan forest SOC distribution and influencing factors.