山西高原落叶松人工林土壤呼吸的空间异质性

基于对华北落叶松(Larix principis-rupprechtii)人工林样地3个取样尺度(4、2、1 m)土壤呼吸(Rs)及其影响因子的观测,运用传统和地统计学的方法分析了Rs的空间变异性及其与影响因子之间的内在联系.传统统计分析表明:Rs及其它相关因子的空间变异均属于中等变异;Rs与10 cm、15 cm深度的土壤温度(T10、T15)和全氮(N)呈极显著正相关(P0.01),与凋落物含水量(Lm)呈显著正相关(P0.05),与碳/氮比(C/N)呈显著负相关(P0.01),与5 cm深度的土壤温度(T5)、土壤水分(Ws)、凋落物量(Lw)和全碳(C)相关性不显著(P0.05);多元逐步回归分析表明:Lm、T10、N和Ws这4个因子能解释土壤呼吸空间变化的36%.地统计学分析表明:Rs具有中等程度的空间自相关性,随机部分引起的空间异质性占39.5%,结构因素占60.5%,气候、地形、土壤等结构因素起着主导作用;不同土壤指标的变程不相同,Rs和T10的变程差异不大,在25 m左右;土壤各指标的分维数大小依次为:Lw(1.95)=C/N比(1.95)N(1.91)C(1.89)Rs(1.78)Lm(1.77)Ws(1.69)T10(1.42).Rs的空间分布模式与T10、Lm、C和N的空间分布模式较为一致,而与Ws、C/N比的空间分布模式不同;在同一置信水平和估计精度下,不同土壤指标的必要采样数量不相同,取决于该指标的空间变异程度.

Spatial Heterogeneity of Soil Respiration in a Planted Larch Forest in Shanxi Plateau

Based on the data from a planted larch forest in Panquangou Natural Reserve of Shanxi Province, at three sampling scales (4, 2, and 1 m, respectively), soil respiration (R_s) and its affecting factors including soil temperature at 5 cm (T₅), 10 cm (T₁₀), and 15 cm (T₁₅) depths, soil water content (W_s), litter mass (L_w), litter moisture (L_m), soil total carbon (C), and soil total nitrogen (N) were determined. The spatial heterogeneities of R_s and the environmental factors were further analyzed and their intrinsic correlations were established. The results of traditional statistics showed that the spatial variations of R_s and the all measured factors were in the middle range; R_s were highly significantly positively correlated with T₁₀, T₁₅, and N (P<0.01); significantly positively correlated with L_m (P<0.05); highly significantly negatively correlated with C/N ratio (P<0.01); and not significantly correlated with T₅, W_s, L_w and C (P>0.05). Multiple stepwise regression a2015-4-21 factors of L_m, T₁₀, N, and W_s together accounted for 36% of R_s heterogeneity. The results of geo-statistical analysis demonstrated that R_s was in a medium spatial autocorrelation; random and structural factors accounted for 39.5% and 60.5% of R_s heterogeneity, respectively. And the factors such as climate, landform, and soil played a leading role. The results also illustrated that the ranges for soil factors were different and the range for both R_s and T₁₀ was 25 meters. The fractal dimension of the soil index was in the following order: L_w and C/N ratio (1.95) > N (1.91) > C (1.89) > R_s (1.78) > L_m (1.77) > W_s (1.69) > T₁₀ (1.42). The spatial distribution of R_s was in consistent agreement with those of T₁₀, L_m, C, and N; but different with those of W_s and C/N ratio. With a fixed cofidence level and certain estimated accuracy, the required sampling number of each item differed, corresponding to its spatial variation degree.