Physical and chemical property of soil of cunninghamia lanceolata plantations by the unusual heavy snow/ice disaster occurred in early 2008
DING Xiaogang1,2,HE Qian3,ZHANG Fangqiu2,LI Jiyue3*,FAN Shunjiang3,CHEN Xiaoyang3 1.Key Laboratory for Silviculture and Conservation of Ministry of Education,Beijing Forestry University,Beijing 100083,China;2.Guangdong Forest Research Institute,Guangzhou 510520,China;3.College of Forestry,South China Agricultural University,Guangzhou 510642,China
In August 2008 representative sample plots(less affected by snow disaster,damaged by the snow disaster,clear-cutting plots after the snow disaster) were selected to check physical and chemical properties of soil with field investigation and laboratory analysis from the Chinese fir plantations in the Tianjinshan state owned forest farm of Guangdong Province.The results showed that:(1) soil bulk density at 0-60 cm depth from damaged plots was 8.1 ~ 16.4% higher than that from undamaged plots,while the porosity and soil moisture content were 8.9 ~ 11.9% and 17.1 ~ 28.6% lower,respectively.The soil bulk density in the plots with the treatment of cleaning up after clear-cutting showed 1.5 ~ 9.5% less than those without damage;while porosity and the soil moisturecontent were 1.2 ~ 5.9% and 44.2 ~ 68.1% higher separately.(2) The soil pH value was not affected by the snow disaster.However,the organic matter content in the shallow(0-40 cm) soil declined 1.3 ~ 9.4% than undamaged plots,while that in the deep( 40 cm) soil increased 30.5%.Total nitrogen,total phosphorus,available nitrogen,available phosphorus and available potassium content from different soil layers decreased 13.4%,30.3%,16.7%,37.6% and 37.2%,while the total K content increased 21.0% significantly.Soil exchangeable calcium and exchangeable magnesium significantly reduced 28.1% and 43.4% separately.With the treatment of cleaning up after the clear-cutting,the organic matter content increased 207.9 percent than those without damage,and soil total nitrogen,total potassium,available nitrogen and phosphorus content increased 138.7%,10.2%,161.3% and 540.0%,respectively.However,the total phosphorus,available potassium,exchangeable calcium and exchangeable magnesium content decreased 2.6%,9.0%,28.7% and 24.3%,respectively,which showed inconsistent result in different soil depth.(3) The occurrence of snow disasters increased the soil compaction of Chinese fir plantations,which was not conducive to soil respiration,air conduction and accumulation of soil nutrients.After clean-up,the soil became more porous,more permeable,and water content increased,which was conducive to the enhancement of soil aggregate structure,soil microbial activity and soil nutrient accumulation and transformation.Therefore,clean-up the damaged forest lands after the snow disaster in time was vital to vegetation restoration.