尾叶桉林下5种木本植物土壤微生物群落特征

Soil Microbial Community Characteristics of 5 Tree Species in Eucalyptus urophylla Plantation

开展人工林下主要木本植物的根际微生物群落特征的研究,可以为增加人工林的生物多样性、维持林地肥力和提高经济效益提供依据。在广东鹤山森林生态系统国家野外科学观测研究站6年生尾叶桉(Eucalyptus urophylla)人工林下,选择自然生长的野牡丹(Melastoma candidum)、山鸡椒(Litsea cubeba)、桃金娘(Rhodomyrtus tomentosa)、秤星树(Ilex asprella)和栀子(Gardenia jasminoides)5种木本植物,通过切根处理排除其他植物根系的作用,并利用常规分析和磷脂脂肪酸(PLFA)分析等方法,研究了这5种植物根际土壤的理化特征、土壤微生物量和微生物群落特征,同时采用丰富度指数(Richness,SR)、香农威纳多样性指数(Shannon-Wiener index,H′)和均匀度指数(Evenness,J)评估了5种木本植物的土壤微生物多样性。结果表明,(1)切根处理和原状(不切根处理)不论在旱季和雨季,5种木本植物根际周围的土壤p H值、土壤含水量和土壤有机碳SOC均无显著差异(P<0.05);土壤微生物PLFA总量也没有显著差异。(2)虽然不同植物种类间部分微生物结构组成存在差异,但通过PCA分析以及对比土壤微生物群落的丰富度指数、多样性指数和均匀度指数发现,原状和切根处理在5种木本植物之间的微生物结构组成没有明显差异。这说明在桉树人工林中,5种林下木本植物对土壤微生物群落的影响相对乔木树种和土壤本身要小,今后在这5种木本植物中选择桉树林下种植物种时,可以主要从地上生物量和经济价值的角度综合考虑。

Understory plays crucial roles in driving the ecosystem processes and functions. For the management of plantation, suitable understory may not only increase the capacity of carbon sequestration, but also can maintain soil fertility and improve the economic benefits, which would contribute to the sustainable development. Therefore, a study was conducted on the main understory species in an Eucalyptus urophylla （six years old） plantation in Heshan National Field Research Station of Forest Ecosystem. Five naturally generated understory species （i.e.,Gardenia jasminoides,Ilex asprella,Litsea cubeba,Rhodomyrtus tomentosa, and Common Melastoma） were chosen and the roots of other plants were excluded by trenching. The soil physical-chemical properties and microbial community composition were analyzed. Also the richness index （SR）, diversity index （H′） and evenness index （J） were calculated to evaluate the diversity of soil microbial biomarkers for the five understory species. No significant differences of the soil pH, soil water content and soil organic carbon were found between trenching and control plots in both dry and rainy season. Furthermore, the total soil microbial biomass （PLFAs） did not differ in the trenching plots compared with those in the control plots. Although soil microbial community composition varies with different understory species, both the PCA analysis and diversity indices of the soil microbial biomarkers showed that there was no significant difference between the trenching and control plots. Our result indicated that these five understory species in Eucalyptus plantation did not affect soil properties; therefore, the aboveground biomass and economic values of understory species should be concerned when selecting the understory commercial tree species.