南亚热带海岸沙地不同林分土壤微生物功能多样性及影响因素

Microbial functional diversity and corresponding impact factors of five typical forests on coast sandy land in South Asian subtropical zone

以福建省东山县海岸沙地4种人工林分(木麻黄Casuarina equisetifolia、卷荚相思Acacia crassicarpa、湿地松Pinus elliottii、尾巨桉Eucalyptus grandis×E. urophylla及天然次生林Secondary Forest)为研究对象,采用Biolog-eco微平板法研究了南亚热带海岸沙地表层(0～10 cm)土壤微生物碳源代谢活性及多样性特征,分析了不同树种土壤微生物功能多样性、土壤理化性质影响的差异及相关性。结表果明:1)不同林分对土理化性质的影响存在显著差异(P <0.05),与人工林分相比,天然次生林土壤有效磷、全碳、速效钾含量及阳离子交换量均较高,而4种人工林分之间差异不明显;2)主成分分析(PCA)表明,与人工林分相比,天然次生林有较独特的碳源利用方式和较高的活性;碳水化合物类、氨基酸类、胺类是滨海沙土微生物利用的主要碳源;3)土壤微生物功能指数与土壤pH、有效磷、有机碳含量显著正相关,较低的有机碳、有效磷含量可能是限制滨海沙土微生物功能发挥的关键制约因素。4)在防护林更新改造过程中可通过套种乡土阔叶树种、增施磷肥等措施,调节土壤pH值,提高土壤有机碳及有效磷含量,增强土壤微生物活性,从而促进沙土质量的持续改良。

Five kinds of typical forests growing on subtropical coastal sandy soil in Dongshan county,Fujian province were studied,such as Acacia crassicarpa plantation,Casuarina equisetifolia plantation,Pinus elliottii,Eucalyptus grandis × E.urophylla plantation,and natural secondary forest.By using biolog-eco microplate method,the metabolic activity and diversity of soil microbial carbon sources in the sandy surface layer (0-10 cm) of the south subtropical coast were studied,and the differences and correlations of soil microbial functional diversity and soil physical and chemical properties among different tree species were analyzed.The results are as follows. 1) There were significant differences in the effects of different stands on soil physical and chemical properties (P < 0.05);Compared with the artificial forest stand,the soil available phosphorus,total carbon,available potassium and cation exchange were higher in the natural secondary forest,but the differences among the four artificial forests were not obvious.2) The results of principal component analysis (PCA) indicate that the natural secondary forests have more unique carbon source utilization and higher activity than artificial forest stands;and carbohydrates,amino acids,and amines are the main carbon sources of microbial communities used on coastal sandy land.3) Soil microbial functional index was positively correlated with soil pH,available phosphorus and organic carbon content,and lower organic carbon and available phosphorus content may be the key limiting factors for giving full play to microbial function in coastal sandy soil.4) During the protection forest renovation process,native broad-leaved tree species should be inter-planted in artificial forest,and application of phosphate fertilizer should be increased to adjusting soil pH value,increase soil organic carbon and available phosphorus content,and enhance soil microbial activity,so as to promote the continuous improvement of sandy soil quality.