杉木成熟林细根形态与功能特征的海拔梯度变异特点

为探究植物对环境变化的适应策略,在安徽省金寨县天马国家自然保护区,以不同海拔高度(750、850、1000、1150 m)杉木(Cunninghamia lanceolata)成熟林为对象,采用土钻法获取土壤细根样品,分别测定了不同海拔不同土层(0—10 cm、10—20 cm、20—30 cm)土壤细根生物量、形态特征参数和碳氮含量。结果表明:(1)随海拔梯度增加,0—30 cm土层细根生物量、根长密度、比根长、表面积密度、体积密度均呈先减少后增加趋势,在海拔750 m生物量最大,其余指标在海拔1150 m最大;随土层深度增加,同一海拔细根生物量、根长密度、表面积密度、体积密度均呈减少趋势。(2)随海拔梯度增加,0—30 cm土层细根C和N含量呈先增加后减少趋势,C/N比呈先减少后增加再减少趋势;随土层深度增加,同一海拔细根C含量呈先减少后增加趋势,N含量呈降低趋势,C/N比呈上升趋势。(3)细根N含量与生物量、根长密度和体积密度显著正相关,C/N比与生物量、根长密度、表面积密度和体积密度极显著负相关。(4)土壤水分对细根生物量及其形态指标影响显著。

Fine root morphological characteristics and its functions in mature Chinese fir plantations along an elevation gradient in Dabie Mountains

In order to reveal the adaptation strategies of plants to environmental changes, the mature Chinese fir (Cunninghamia lanceolata) plantations along an elevation gradient (750, 850, 1000 m, 1150 m a.s.l.) were selected in Tianma National Nature Reserve in Anhui Province. Their fine roots at different layers (0-10 cm, 10-20 cm, and 20-30 cm) were sampled to determine the biomass, characteristic parameters, C and N contents. The results showed that fine root biomass, length density, specific root length, surface area density, and volume density at 0-30 cm soil depth initially decreased and then increased with the increase in elevation. The fine root biomass peaked at 750 m, and the other indices showed the maximum values at 1150 m. Fine root biomass, length density, surface area density, and volume density decreased with soil depth at each elevation. The C and N contents of fine root at 0-30 cm soil depth initially increased and then decreased with the increase in elevation. While the C/N decreased at first, and increased later, but decreased again. The C contents of the fine roots decreased over the elevation gradient, however they decreased more in N content. This resulted in increase of C/N ratio. Fine root N content positively significant correlated with biomass, root length density, and volume density. However, C/N ratio negatively correlated with biomass, root length density, surface area density, and volume density. The soil moisture was positively significant correlation with fine roots biomass and its configuration.