亚热带不同海拔黄山松林土壤磷组分及微生物特征

磷是亚热带地区植物生长必需的养分元素之一,海拔梯度可能会改变土壤-植物-微生物系统并影响土壤磷形态及有效性。了解不同海拔土壤磷组分状况,对维持山地森林生态系统可持续发展具有重要的意义。以戴云山地区不同海拔梯度(1300m和1600 m)黄山松林为研究对象,分析了土壤磷组分、微生物群落特征和磷酸酶活性。结果显示:海拔显著影响黄山松林土壤磷组分,与海拔1300 m相比,海拔1600 m处土壤总磷含量减少了48.4%—49.8%,且各磷组分(易分解态磷、中等易分解态磷和难分解态磷)含量也显著降低,淋溶层(A层)土壤的降低程度分别为45.7%、58.6%和38.7%,淀积层(B层)为82.6%、59.9%和31.1%。海拔对土壤微生物群落特征和酶活性亦有显著影响,各类微生物群落和总微生物磷脂脂肪酸含量(PLFAs),以及磷酸双酯酶(PD)活性均表现为海拔1600 m 1300 m,但酸性磷酸单酯酶(ACP)活性呈相反的趋势。冗余分析(RDA)表明,土壤磷组分主要受有机碳(SOC)调控,且SOC与有机磷组分(Na HCO3-Po和Na OH-Po)呈显著正相关;磷酸酶和外生菌根真菌(EMF)也是影响土壤磷组分变化的重要因素。研究表明,土壤有机质含量和微生物群落结构及功能的变化可能是不同海拔黄山松林土壤磷有效性的关键调控因素。

Characteristics of soil phosphorus fractions and microbial communities in Pinus taiwanensis Hayata forests at different altitudes in a subtropical region of China

Phosphorus (P) is an essential nutrient for plant growth in subtropical forest soils. Altitude gradient might modify the soil-plant-microorganisms system and affect P forms and availability. Therefore, it is critical to understand the characteristics of soil P fractions at different altitudes for maintaining the sustainable development of mountain forest ecosystems. Soils were analyzed for P fractions, microbial community composition, and activities of acid phosphomonoesterase (ACP) and phosphodiesterase (PD) in Pinus taiwanensis Hayata forests at different altitudes (1300 and 1600 m) in Daiyun Mountain. The results revealed that the altitudinal gradient studied had a significant effect on soil P factions. Soil total P content decreased by 48.4%-49.8% at 1600 m compared to 1300 m altitude. All P fractions of labile P, moderately labile P, and non-labile P also significantly decreased by 45.7%, 58.6%, and 38.7% in the A horizon, and by 82.6%, 59.9%, and 31.1% in the B horizon, respectively. Furthermore, significant changes occurred between 1300 and 1600 m above sea level, as the soil at higher altitudes showed lower activities of phosphodiesterase and phospholipid fatty acids (PLFAs) of all microbial communities than those of the soil at lower altitudes. Conversely, activities of acid phosphomonoesterase showed an increasing trend. Redundancy analysis (RDA) indicated that the changes in P fractions were mainly driven by soil organic carbon (SOC); moreover, soil organic P (NaHCO₃-Po and NaOH-Po) was positively correlated with SOC. In addition, phosphatase and ectomycorrhizal fungi (EMF) were important factors affecting changes in P fractions of the soil. Our study indicated that altitude had an effect on the accumulation of soil organic matter and microbial community composition and function, which affected soil P availability and cycling.