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Scientia Silvae Sinicae ›› 2014, Vol. 50 ›› Issue (5): 8-16.doi: 10.11707/j.1001-7488.20140502

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Soil Microbial Biomass Carbon and Nitrogen Concentrations in Four Subtropical Forests in Hilly Region of Central Hunan Province, China

Li Shenglan1,2, Fang Xi1,2, Xiang Wenhua1,2, Sun Weijun1,2, Zhang Shiji1   

  1. 1. College of Life Science and Technology, Central South University of Forestry and Technology Changsha 410004;
    2. State Key Laboratory of Ecological Applied Technology in Forest Area of South China Changsha 410004
  • Received:2013-04-17 Revised:2014-04-14 Online:2014-05-25 Published:2014-06-06
  • Contact: 方晰

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Abstract:

A chloroform fumigation extraction method was used to investigate seasonal variations in microbial biomass carbon and microbial biomass nitrogen concentration in four forests (i.e. Cunninghamia lanceolata plantation, Pinus massoniana+ Lithocarpus glaber mixed forest, Choerospondias axillaris deciduous broad -leaved forest, and L. glaber+ Cyclobalanopsis glauca evergreen broad-leaved forest) in middle hilly region of Hunan Province. Correlation analyses were performed on soil microbial biomass carbon and nitrogen concentration against soil nutrients and moisture. The results showed that the average concentration of total soil organic carbon and total nitrogen in all soil layers were similar and increased with increase in the tree species richness in stands. The concentrations of microbial biomass carbon and nitrogen were higher in C. axillaris deciduous stand and L. glaber+ C. glauca evergreen broad-leaved stand than that in P. massoniana+ L. glaber mixed stands and C. lanceolata plantations. The highest concentrations of microbial biomass carbon and nitrogen occurred in C. axillaries deciduous stand while the lowest concentrations occurred in C. lanceolata plantation. The ratios of microbial biomass carbon to total organic carbon and microbial biomass nitrogen to total nitrogen were highest in C. axillaris deciduous stand, and lowest in P. massoniana+ L. glaber mixed stand, ranging from 2.3%-2.9% and 4.5%-6.4%, respectively. The seasonal variations in concentrations of microbial biomass carbon and nitrogen displayed a single peak (the highest value was in summer while the lowest value was in winter, or the highest value was in autumn while the lowest value was in spring). The seasonal fluctuation amplitude of microbial biomass carbon in P. massoniana+ L. glaber mixed forest, C. lanceolata plantation were significantly different compared with other two forests, but there was no significant difference in microbial biomass nitrogen; There were positive and significant (P < 0.05) correlations between soil microbial biomass carbon and nitrogen with total organic carbon, total nitrogen and alkaline hydrolytic nitrogen, but no significant correlation with soil water contents (P>0.05). The results indicated that soil moisture was not the controlling factor for seasonal variations in soil microbial biomass in the four forests. The differences in total organic carbon and total nitrogen concentrations were affected by environmental factors exsiting in the four forests and in turn resulted in differences in microbial biomass carbon and nitrogen concentration and their seasonal variations in the four forests.

Key words: hilly region of central Hunan Province, Cunninghamia lanceolata plantation, successional stages, secondary forests, soil microbial biomass carbon and nitrogen

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