摘要:农作区是峰丛洼地区居民生产生活的聚集区，土地利用强度大，石漠化风险性高，是生态保育的焦点区。合理的耕作模式是该区土地可持续利用与生态安全的基础。以桂西北典型峰丛洼地农作区--广西果化岩溶生态研究基地为研究区，采集典型农田类型火龙果地（相当于保护性耕作模式，HF）、玉米地（相当于翻耕模式，MF）、甘蔗地（相当于少耕+秸秆还田耕作模式，SF）和水稻田（PF）的土壤样品，分析其土壤真菌群落结构、功能及土壤理化性质，并将其与退耕还林（人工林，FL）、退耕还草（自然恢复，AF）样地相应性质进行对比，以评价不同耕作模式的生态环境效应，为该区可持续耕种与生态保育提供科学依据。结果表明：（1）与退耕模式（FL、AF）相比，耕作活动（HF、MF、SF）降低了土壤pH值与有机质、全氮含量，改变了土壤粒度（粘粒、粉砂、砂砾）组成比例；（2）HF、MF、PF、FL提升了土壤真菌α多样性指数，SF、AF反之；土壤真菌α多样性指数均随着土壤深度的增加而下降；（3）各耕作模式及其不同土层的优势真菌门均为Ascomycota、Basidiomycota、Mortierellomycota；耕作没有改变土壤优势真菌的种类，但影响着其相对丰度；（4）β多样性分析结果显示，各耕作模式真菌群落结构自成一类，但HF与退耕模式间真菌群落结构差异较小；0-10 cm、10-20 cm间的真菌群落结构差异较小，但两者与20-40 cm相差较大；FL、SF和 HF具有较多的显著性差异物种（Biomarker），其次为MF、PF，AF最少；（5）土壤pH值、碳氮比、氮磷比是影响土壤真菌群落结构的重要因子；（6）耕作模式对土壤功能类真菌影响明显，HF、MF、SF、PF土壤腐生营养型真菌、病理营养型真菌的含量显著高于FL、AF；同时，SF中的土壤腐生营养型真菌含量最高；HF中的共生营养型真菌含量最高。HF具有与退耕模式较为一致的土壤真菌群落结构特征，拥有最丰富的共生营养型真菌与较优的土壤理化性质，具有良好的生态效应。



Abstract:The farming areas in karst peak-cluster depressions, where residents live densely and utilize the land more intensively, pose a great risk for rocky desertification, and are usually seen as focal regions of ecological conservation. Appropriate tillage modes can set the foundation for sustainable land use and ecological security in the area. This study was conducted at the Guohua Karst Ecological Experimental Station in southwest China (a typical farming area in the peak cluster depression), to evaluate tillage effects on soil fungal community composition, fungal functions, and physicochemical properties. Major types of croplands, including pitaya field (representing conservation tillage, HF), maize field (representing plowing tillage, MF), sugarcane field (representing minimum tillage+straw return, SF), and paddy field (PF), were studied in contrast to forestland (artificial forest transformed from cropland, FL) and grassland (rehabilitated naturally from abandoned farmland, AF). The results showed that:(1) by comparison with the rehabilitated-land modes (FL, AF), the HF, MF and SF not only reduced the soil pH, soil organic matter contents (SOM), and total nitrogen (TN) but also altered the particle size distribution (clay, silt, sand). (2) The HF, MF, PF and FL increased the abundance-based coverage estimator (ACE) index and Shannon index of soil fungal communities, while SF and AF decreased the α-diversity index. The α-diversity index exhibited the indices declined as the soil depth increased. (3) In the study area, the dominant fungal groups were Ascomycota, Basidiomycota, and Mortierellomycota. Tillage did not change the species of dominant fungal strains, but affected their relative abundance. (4) The analysis of β-diversity showed that soil fungal community structure of each tillage mode was unique, however similarity existed among the HF and rehabilitated-land modes. Soil fungal community structures at 0-10 cm soil layers are similar to those at 10-20 cm, but they were largely different from those of the 20-40 cm depth. The FL, SF and HF had more distinctive species (biomarkers), followed by MF, PF, and the least was AF. (5) Soil pH, C/N, N/P were important factors affecting soil fungal community structures. (6) The effect of tillage modes on soil fungal function was obvious, pathotrophic fungi and saprotrophic fungi in HF, MF, SF, PF soil were significantly higher than those of FL and AF, moreover, the content of saprotrophic fungi in SF was the highest, HF had the highest symbiotrophic fungi. The characteristics of fungal community structures were similar among the HF, FL and AF, suggesting that no-tillage was conducive to maintaining the natural properties of soil fungal community structures, and shows a positive soil ecological effect.





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