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为了探讨西双版纳地区土地利用变化对土壤有机质含量及其化学组成的影响 ,选取了相邻的次生林、耕种 6年的农田和定植 3年的橡胶园样地 ,对其 0～ 5cm和 5～ 2 0cm表层土壤中有机质含量、胡敏酸的光谱学特性进行了分析。研究结果表明 ,次生林转变为农田之后 ,0～ 5cm和 5～ 2 0cm表层土壤有机质含量分别降低 33.6 %和2 3.7% ;而次生林转变为橡胶园 ,分别降低 2 8.6 %和 2 7.6 %。胡敏酸可见_红外光谱结果显示 ,次生林转变为农田和橡胶园后 ,0～ 2 0cm表层土壤E4/E6显著降低 ,这表明胡敏酸化学组成当中芳香族结构增加。傅立叶变换红外光谱结果同样表明 ,土地利用变化影响土壤有机质的化学组成。次生林转变为农田和橡胶园后 ,胡敏酸中羧基和酚基结构比例降低 ,而脂肪族、芳香族和多聚糖比例增加。
In order to investigate the effect of land use change on soil organic matter and its chemical composition in Xishuangbanna, the adjacent secondary forest, farmland cultivated for 6 years and rubber plantation planted for 3 years were selected to study the effects of land use change on soil organic matter content and its chemical composition in 0 ~ 5cm and 5 ~ 20cm The content of organic matter in surface soil and the spectroscopic properties of humic acid were analyzed. The results showed that after the secondary forest was converted into farmland, the organic matter content in surface soil of 0 ~ 5cm and 5 ~ 20cm decreased by 33.6% and 23.7% respectively, while the secondary forest was changed into rubber plantation, which decreased by 22.6% and 22.6% respectively. The results of visible-infrared spectroscopy of humic acid showed that E4 / E6 of 0-20 cm surface soil significantly decreased after secondary forest was converted to farmland and rubber plantation, which indicated that the aromatic structure increased in the chemical composition of humic acid. Fourier transform infrared spectroscopy results also show that changes in land use affect the chemical composition of soil organic matter. After the conversion of secondary forest to farmland and rubber plantation, the proportion of carboxyl and phenolic groups in humic acid decreased while the proportion of aliphatic, aromatic and polysaccharides increased.