间伐对栓皮栎人工林林下荆条根茎叶主要功能性状的影响

Effects of thinning on the functional traits of understory Vitex negundo var.heterophylla in Quercus variabilis plantation

【目的】研究间伐对栓皮栎Quercus variabilis人工林林下荆条Vitex negundo var. heterophylla根、茎、叶功能性状的影响,为人工林林分结构优化和林下幼苗更新保护提供理论基础。【方法】以间伐后3 a栓皮栎人工林灌木层荆条为研究对象,比较其叶面积、比叶面积、叶干物质质量分数、茎干物质质量分数、总根长、比根长等结构性状,以及植株各器官全氮、全磷、全钾和总有机碳质量分数等化学性状的差异性,研究植物功能性状与林下光环境及土壤理化特征的关系。【结果】间伐后荆条地上部分植物功能性状指标(叶总有机碳、叶面积、比叶面积、叶有机氮、茎总有机碳)和地下部分植物功能性状指标(总根长、根体积、根生物量、根总有机碳)均显著高于对照样地(P<0.05)。相关和逐步回归分析结果表明:林下散射辐射是影响荆条叶结构性状的主要因子,林下直射辐射通量、光合有效辐射和太阳总辐射时间是影响叶化学性状的关键因子,茎功能性状主要受林下直射辐射和散射辐射的共同作用。总根长、比根长和根有机碳与土壤非毛管孔隙度、土壤总孔隙度、土壤有机碳和土壤全氮存在显著相关(P<0.05),其中,土壤有机质是影响荆条根功能性状的关键因子。【结论】间伐能显著促进栓皮栎人工林下荆条叶和根功能性状的发育,对茎功能性状的影响较弱。

[Objective] The objective of this study is to explore the effect of thinning on the functional traits of roots, stems and leaves of Vitex negundo var. heterophylla under Quercus variabilis plantation in order to provide theoretical basis for the optimization of plantation structure and the regeneration and protection of understory seedlings. [Method] The V. negundo var. heterophylla in the shrub layer of Q. variabilis plantation3 years after thinning was taken as the research object, and the differences of leaf area, specific leaf area, leaf dry matter content, stem dry matter content, total root length, specific root length and other structural traits, as well as total nitrogen, total phosphorus, total potassium and total organic carbon content in various plant organs were compared. The relationship between plant functional traits and the understory light environment and soil physical and chemical characteristics was studied. [Result] After thinning, the aboveground functional traits of plants of V. negundo var. heterophylla such as total leaf organic carbon, leaf area, specific leaf area, leaf organicnitrogen, stem total organic carbon, and the underground functional traits of plants such as root length, root volume, root biomass, the total organic carbon content of roots were significantly higher than those of the control plot(P<0.05). Correlation and stepwise regression analysis results showed that scattered radiation was the main factor affecting the structural properties of V. negundo var. heterophylla leaves. Direct radiation flux,photosynthetically active radiation and total solar radiation time were the key factors affecting leaf chemical properties, while stem functional properties were mainly affected by the direct radiation and scattered radiation under the forest. Total root length, specific root length and root organic carbon content were significantly correlated with soil non-capillary porosity, soil total porosity, soil organic carbon and soil total nitrogen(P<0.05), among which soil organic matter content was the key factor affecting functional traits. [Conclusion]Thinning can significantly promote the development of the functional traits of leaves and roots of Q. variabilis plantation, and has a weak effect on stem functional traits.