干热河谷冲沟沟岸葛藤不同覆被状况及土壤性质差异分析

Analysis of soil properties in gully banks under different coverage of Kudzu in a dry-hot valley region

沟岸是干热河谷冲沟系统中土壤生态环境最为恶劣的地带,其水热矛盾突出、土层浅薄、土壤贫瘠。探讨葛藤覆被对沟岸土壤性质的影响,可为沟岸土壤改良与植被恢复奠定基础。以元谋干热河谷区葛藤覆被的冲沟沟岸为研究对象,选取裸露地块作为对照(CK),根据藤本生物量设置4个处理(T1:309.70 g/m^2鲜被物,T2、T3、T4:594.34、1103.43、1693.27 g/m^2枯落物),对比研究了葛藤不同覆被状况对沟岸土壤性质的影响。结果表明:沟岸土壤性质受葛藤覆被类型(鲜/枯)及生物量共同影响。(1)较裸露沟岸(11.05%),枯藤覆被有益于保持其下土壤水分(13.30%—18.90%),鲜藤覆被下土壤水分则明显降低(7.36%);较裸露沟岸,鲜、枯藤覆被均有助于增加其下土壤毛管孔隙度。(2)较裸露沟岸,鲜藤覆被下沟岸土壤有机质、铵态氮、硝态氮、有效磷、速效钾含量大都呈现出不同程度的降低,枯藤覆被沟岸上述土壤养分含量则整体增加,且大都呈现出随枯藤覆被量增加而增加的规律。(3)较裸露沟岸(3.24 nmol/g),鲜、枯藤覆被沟岸土壤总PLFA(总磷脂脂肪酸量Phospholipids fatty acid)量明显提升,T1—T4处理土壤的总PLFA量分别为裸露沟岸的10.5、2.6、2.6倍和6.5倍。研究成果对于干热河谷冲沟系统退化土壤的改良及植被恢复具有重要的指导意义。

Gully banks are the most severely affected parts of dry-hot valley gully ecosystems, which are characterized by contradictions between heat, shallow water, and barren soil. To evaluate the effects of Kudzu cover on soil properties and lay a foundation for soil improvement and vegetation restoration on gully banks. We choose gully banks covered by Kudzu as the research object and designated five treatments, including a control group （CK：0 g/m2）, fresh vegetation cover （T1：309.70 g/m2）, and withered vegetation cover （T2：594.34 g/m2, T3：1103.43 g/m2, and T4：1693.27 g/m2） to analyze the effects of different Kudzu cover on soil properties. In comparison with CK, the results showed that ① the soil covered by withered Kudzu retained soil moisture, whereas those covered by fresh Kudzu had significantly less soil moisture. ② The soil covered by fresh Kudzu was lower in soil organic matter, ammonium nitrogen, nitrate nitrogen, available phosphorus, and available potassium, whereas the soil covered by withered Kudzu had high soil nutrient content that increased with increase in vegetation biomass. ③ The soil covered by Kudzu increased in total phospholipid fatty acids （Total PLFAs）, and the Total PLFAs from T1, T2, T3, and T4 were, respectively, 10.5, 2.6, 2.6, and 6.5 times that of CK. This study provides important information to significantly guide soil improvement and vegetation restoration in dry-hot valley gully ecosystems.