喀斯特地区不同植被恢复类型对土壤化学及微生物生物量的影响

Effects of different vegetation recovery types on soil chemical and microbial biomass properties in Maolan Karst region

为了更好地理解西南喀斯特地区不同植被恢复方式下的土壤质量,对原始林（对照）、次生林、竹林、马尾松林和草地等5种植被类型的土壤化学和微生物生物量特征进行了调查。结果表明：受母岩碳酸盐的风化和淋溶作用的影响,土壤p H呈中性的水平;土壤有机碳（SOC）、全氮（TN）、全磷（TP）、钙（Ca）、镁（Mg）、钾（K）和钠（Na）含量分别分布在23.4~142、1.5~13.5、0.1~0.9、2.7~16.4、1.7~5.9、2.0~7.1、0.13~0.48 g/kg之间;土壤无机态NH＋4-N和NO-3-N的含量分别分布在0.43~8.83和0.01~9.71 mg/kg之间;土壤交换性Ca2＋、Mg2＋、K＋和Na＋分别分布在10.32~33.41、0.57~5.58、0.05~0.34、0.02~0.03 cmol/kg之间;土壤微生物生物量碳（MBC）及MBN和MBP的含量分别分布在388.3~3 191.8、65.4~624.8和3.9~67.5 mg/kg之间。不同的植被类型土壤化学性质和微生物生物量呈显著差异,原始林和次生林的土壤化学性质高于其他植被类型,土壤微生物生物量的含量差异也呈现同样的结果,与不同植被类型有机质的输入量有关。不同植被类型土壤化学性质与土壤微生物生物量之间呈显著的相关关系。总体而言,单一树种造林,尤其是马尾松纯林的营造将不利于土壤的恢复,植被的自然恢复对于喀斯特地区土壤质量的提高是一种有效的途径。

In the past two decades,numerous attempts（ afforestation,natural regeneration,etc.） have been made to promote recovery of the degraded soil such as reconverting farmlands to forestlands in Guizhou Karst region,southwest of China. For better understanding of effects of different vegetation types on the chemical and microbial biomass properties of the soil,five vegetation types,namely natural forest（ control）,natural regeneration,bamboo plantation,pine plantation and grassland（ control）,were investigated in this region. The results indicated： a range of soil p H from near neutral was observed,as a result of weathering and eluviation in the Karst area. Soil organic carbon,total nitrogen,total phosphorus,calcium,magnesium,potassium,sodium varied from 23. 4- 142,1. 5- 13. 5,0. 1- 0. 9,2. 7- 16. 4,1. 7- 5. 9,2. 0- 7. 1,and 0. 13- 0. 48 g / kg,respectively. Soil ammonium- N and nitrate- N varied from 0. 43- 8.83,and 0. 01- 9. 71 mg / kg,respectively. Exchangeable calcium ion,magnesium ion,potassium ion,sodium ion varied from 10. 32- 33. 41,0. 57- 5. 58,0. 05- 0. 34,0. 02- 0. 03 cmol / kg,respectively. Soil microbial biomass carbon,soil microbial biomass nitrogen,and soil microbial biomass phosphorus varied from 388. 3- 3 191. 8,65. 4- 624.8,and 3. 9- 67. 5 mg / kg,respectively. The chemical and microbial biomass properties of the soil differed significantly under different vegetation types. Soil chemical properties under natural regeneration with a higher organic matter contentshowed significantly higher values than those under other vegetation types. Higher microbial biomass carbon,nitrogen and phosphorus values were also observed in natural forest and natural regeneration. Results from this study suggested singlespecies plantations,especially that the pure plantation of Pinus massoniana had a negative impact on soil chemical and microbial biomass properties,while the natural regeneration might be a more effective way for improving soil quality in the degraded Karst region.