花椒(Zanthoxylum bungeamun)种植年限对土壤有机碳矿化拟合及化学分离稳定性碳的影响

Effects of planting duration of Chinese prickly ash orchard on soil organic carbon mineralization and chemically stable organic carbon

以贵州西南部典型石漠化治理示范区内5、17、30年生花椒(Zanthoxylum bungeamun)林土壤为研究对象,以乔木林(约60年)土壤为对照,采用方程拟合的方法研究土壤有机碳矿化动态变化,并探讨种植花椒对土壤有机碳矿化拟合和化学分离稳定性碳的影响。结果表明:土壤有机碳矿化数据与双指数方程的拟合效果良好,相关系数均达到0.95以上,土壤缓效性碳含量(Cs)与土壤有机碳累计矿化量(Cmin)的相关性达到了极显著水平(R=0.792,P<0.01);Na2S2O8残留物有机碳含量在各土层均以乔木林最高,约24.5±0.7 g·kg-1,占土壤总有机碳(SOC)的79.5%;H_2O_2残留物有机碳含量及其占SOC百分比在0~15 cm和30~50 cm层分别以30年生花椒林(PO-30)和17年生花椒林(PO-17)最高,分别为7.59±0.8 g·kg-1、26.6%和6.41 g·kg-1、40.1%;HF溶解性有机碳含量及其占SOC的百分比在各土层均以PO-17最高;4种林型的土壤活性有机碳含量仅占缓效性碳含量的1.6%~29.3%,且缓效性碳含量与培养92天土壤有机碳累积矿化量相接近,但缓效性有机碳矿化速率(ks)的变化波动较小(0.013~0.025),且以30年生花椒林土壤的0~15 cm、15~30 cm层最高。随着种植年限的增加,土壤活性有机碳和缓效性有机碳含量整体分别表现出递增和递减的趋势。因此,合理的花椒种植年限能够改善土壤质量及固碳能力,为石漠化土壤的修复提供一定参照。

With 5-, 17-, 30-year-old Chinese prickly ash orchards （designated as PO5, PO17, PO30 respectively） and a forest land （FL, about 60 years） as control in a demonstration area of desertification control in southwestern Guizhou as our research objects, the dynamics of soil organic C mineralization were assessed by fitting equation methods. The effects of planting Chinese prickly ash orchards on soil organic C mineralization and chemically stable organic C were analyzed. The results showed that the double exponential equation fit well for the variation of soil organic C mineralization, with a correlation coefficient of 〉0.95. The correlation of soil slowacting C with cumulative C mineralization was significant （R=0.792,P〈0.01）. The concentration of Na2S2O8resistant organic C at all soil layers was highest in the forest compared to the three Chinese prickly ash orchards, whereas its proportion to SOC was the lowest. The concentration and proportion of H2O2resistant organic C at 0-15 cm soil layer were the highest in thePO30, and those at 30-50 cm were the highest in the PO17. The concentration and proportion of HF soluble organic C at all soil layers were the highest in the PO17. Soil organic C concentration of the four forest types accounted for only 1.6%-29.3% of the slowacting C, the concentration of which was close to the cumulative mineralization amount of soil organic C after 92 days. The mineralization rate of slowacting C （ks） fluctuated slightly （0.013-0.025）, and the ks values of PO30 were the highest at 0-15 cm and 15-30 cm layers. With the increases of cultivation duration, soilactive organic C and slowacting C concentrations showed increasing and decreasing trend,respectively. In conclusion, reasonable cultivation duration of Chinese prickly ash orchard can improve soil quality and C sequestration.