CAJ | 학술논문

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0～5 cm和5～20 cm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,～5 cm和5～20 cm 表层土壤有机质含量分别降低33.6%和23.7%;而次生林转变为橡胶园,分别降低28.6%和27.6%.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,～20 cm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.
위료탐토서쌍판납지구토지이용변화대토양유궤질함량급기화학조성적영향,선취료상린적차생림、경충6년적농전화정식3년적상효완양지,대기0～5 cm화5～20 cm표층토양중유궤질함량、호민산적광보학특성진행료분석.연구결과표명,차생림전변위농전지후,～5 cm화5～20 cm 표층토양유궤질함량분별강저33.6%화23.7%;이차생림전변위상효완,분별강저28.6%화27.6%.호민산가견-홍외광보결과현시,차생림전변위농전화상효완후,～20 cm표층토양E4/E6현저강저,저표명호민산화학조성당중방향족결구증가.부립협변환홍외광보결과동양표명,토지이용변화영향토양유궤질적화학조성.차생림전변위농전화상효완후,호민산중최기화분기결구비례강저,이지방족、방향족화다취당비례증가.
Previous studies have suggested that land use changes affect not only the content of soil organic matter (SOM),but also the chemical composition of SOM. The objective of this study was to confirm this finding at a site in tropical China. To understand the effect of land use changes on the quantity and quality of SOM,spectroscopic characteristics of humic acids from the topsoil (0-5 cm and 5-20 cm) and subsoil (20-40 cm) from a secondary tropical forest,a cropland,and a rubber tree plantation were investigated in Xishuangbanna,southwest China. The cropland had been cultivated for six years following the clearing of a secondary forest,and the 3-year old rubber tree plantation had been established on land that had been cultivated for 3 years following clearing of a secondary forest. Humic acids were extracted using an alkaline solution (0.1 M NaOH),and the extractions analyzed using Ultraviolet-visible spectroscopy (UV-VIS) and Fourier-Transform infrared spectroscopy (FT-IR). Six years after the conversion of secondary forest to cropland,SOM content in the 0-5 cm and 5-20 cm topsoil samples were reduced by 33.6% and 23.7%,respectively. Conversion of secondary forests to rubber tree plantations also greatly reduced SOM content by 28.6% in the top horizon (0-5 cm) and 27.6% at 5-20 cm depth. Comparison of UV-VIS spectra showed that E4/E6 ratios of humic acids from 0-5 cm and 5-20 cm depths in the secondary forest were higher than in the cropland and the rubber tree plantation soils,which indicated that the proportion of aromaticity in humic acids in the secondary forest was lower than the other two ecosystems. FT-IR spectra also indicated that land use change influenced the chemical composition of SOM. The proportion of carboxylic and phenolic groups in the humic acid was higher and the aliphatic and aromatic groups and polysaccharide-like substances were lower in the secondary forest than in the soils from the cropland and rubber tree plantation.