桉树与红锥混交对土壤养分及林下植物功能群的影响

Effects of a mixture of Eucalyptus and Castanopsis hystrix on soil nutrients and understory plant functional groups

关键词:  桉树×红锥混交林, 植物多样性, 物种丰富度, 土壤养分, 植物功能群

Key words:  mixed Eucalyptus and Castanopsis hystrix plantations, plant diversity, species richness, soil nutrient, plant functional group

摘要:

桉树人工林对生态环境的影响一直是全球性争议的热点问题,桉树与珍贵乡土树种混交的生态环境效应备受关注。为探究桉树混交营林措施对林地土壤养分及林下植物功能群的影响,该研究以桉树纯林(PE)、桉树×红锥混交林(MEC)和红锥纯林(PCH)为对象,开展了林下植物群落及环境因子的调查测定。研究结果显示:不同林分的土壤理化性质具有显著差异,混交林的土壤pH、有效氮(AN)和有效磷(AP)含量显著高于纯林; 而土壤含水量(SMC)、有机碳(SOC)、总氮(TN)含量及C:N和C:P在混交林中没有显著优势,并呈现PE<MEC<PCH的趋势; 土壤容重(SBD)和全磷(TP)含量则呈现PE>MEC>PCH的趋势。混交林显著增加林下木本植物功能群(WFG)的物种丰富度,而PCH显著增加蕨类植物功能群(FeFG)的物种丰富度。混交林的WFG和禾草植物功能群(GFG)的重要值均显著高于红锥纯林,而红锥纯林FeFG的重要值显著高于混交林。主坐标分析结果表明,MEC与PE的林下植物功能群组成差异不显著,但与PCH的差异显著; 冗余分析结果揭示了AN和AP是WFG占优势的主要影响因子,SMC、TN和SOC是FeFG占优势的主要影响因子,SBD是GFG占优势的主要影响因子。以上研究结果表明,在南亚热带地区桉树与红锥混交在一定程度上能够提高林地土壤养分的有效性和林下植物多样性。

Abstract:

The impact of Eucalyptus plantations on the ecological environment has been a hot topic of controversy worldwide. The ecological and environmental effects of a mixture of Eucalyptus and precious native tree species have attracted much attention. In order to explore the effects of management measures in mixed plantations on soil nutrients and understory plant functional groups, we assessed the understory plant communities and environmental factors using pure Eucalyptus plantations(PE), mixed Eucalyptus and Castanopsis hystrix plantations(MEC), and pure C. hystrix plantations(PCH). We found significant differences in the physicochemical properties of soil in the different stands. The soil pH, available nitrogen(AN)content, and available phosphorus(AP)content were significantly higher in MEC than those in PE and PCH. However, we noted no significant advantages in terms of the soil moisture content(SMC), soil organic carbon(SOC)content, total nitrogen(TN)content, C:N ratio, and C:P ratio in MEC, with a trend of PE < MEC < PCH. On the other hand, the soil bulk density(SBD)and total phosphorus(TP)content showed a trend of PE > MEC > PCH. MEC significantly increased the species richness of the understory woody plant functional group(WFG), while PCH significantly increased the species richness of the fern functional group(FeFG). The importance value of WFG and the Gramineae functional group(GFG)were significantly higher in MCH than those in PCH, while the importance value of FeFG was significantly higher in PCH than that in MCH. Principal coordinate analysis revealed no significant differences in the composition of understory plant functional groups between MEC and PE, but revealed significant differences between MEC and PCH. Moreover, redundancy analysis revealed that AN and AP were the main factors influencing the dominance of WFG. SMC, TN content, and SOC content were the main factors influencing the dominance of FeFG, while SBD was the main factor influencing the dominance of GFG. Thus, the mixture of Eucalyptus and Castanopsis hystrix can improve the availability of soil nutrients and the diversity of understory plant communities to some extent in subtropical China.