不同利用方式对棕壤有机碳垂直分布的影响

Effect of different land use on vertical distribution of soil organic carbon in brown soil

采用野外采样和室内分析的方法研究了林地、园地、耕地3种利用方式对典型棕壤总有机碳(TOC)、颗粒有机碳(POC)及重组有机碳(HFOC)在0～20 cm、20～40 cm、40～60 cm 3层次中垂直分布的影响。结果表明,与林地相比,园地和耕地各层次的TOC含量和储量均显著下降;其分布份额和分布比则为园地中、下层略向上层转移,耕地则明显向中、下层转移。3种利用方式下POC的相对数量均随土层加深而递减,林地开垦为园地和耕地后,POC的相对数量仅在园地上、中层显著降低,分别减少6.67和1.70个百分点,而耕地则各层次均显著降低,其相对数量分别减少13.65、5.43和3.03个百分点;HFOC的相对数量随干预强度和土层深度增加而增大,耕地和园地比林地分别高出:上层5.77和4.00个百分点、中层10.44和6.40个百分点、下层7.35和3.92个百分点,且差异均显著。因此,将林地棕壤开垦为园地或耕地后应注重有机物料的投入,以减缓因开垦对有机碳所造成的损失和不尽合理的分布状况。

The effect of three land use patterns（forestland,garden plot,farmland）on the vertical distribution of total organic carbon（TOC）,particulate organic carbon（POC）and heavy fraction organic carbon（HFOC）in typical brown soil were studied by field sampling and laboratory analysis methods.Soil samples（0~20 cm,20~40 cm and 40~60 cm）were collected from each of land use patterns.The results showed that the conversion of forestland to garden plot and farmland decreased the content and reserves of TOC in all levels significantly.Compared with the TOC distribution share and ratio of the forestland,the TOC distribution of garden plot were transferred to the upper form middle and lower layers,but the TOC distribution of farmland were transferred obviously to the middle and lower layers.The relative number of POC decreased with increasing of the depth under three land use patterns.After the conversion of forestland to garden plot and farmland,the POC of garden plot on the middle and lower levels were significantly decreased by 6.67 and 1.70 percentage point,respectively;While the farmland at all levels were significantly reduced by 13.65,5.43 and 3.03 percentage point,respectively.The relative number of HFOC increased with the soil depth and the intensity of intervention.The increasing relative number of HFOC under farmland and garden plot use patterns showed that 5.77 and 4.00 percentage point in the upper,10.44 and 6.40 percentage point in the middle,7.35 and 3.92 percentage point in the lower,respectively,and significant differences.Therefore,we should pay attention to the input of organic matter after the conversion of forestland to garden or farmland,in order to reduce or mitigate the losses that caused by reclamation of organic carbon and its unreasonable distribution.