戴云山黄山松林土壤碳组分的海拔变化特征及影响因素

海拔梯度可能通过多种环境因子影响土壤有机质,土壤有机碳库是土壤有机质的重要组成部分,其微小变化将会产生极其重要的影响。因此海拔差异可能导致海拔间土壤碳库差异。土壤有机碳是反映土壤肥力的重要指标,可能受土壤理化性质和微生物等多种因素的影响。黄山松是高山地绿化和用材的优良树种,近年来戴云山自然保护区内高海拔地区的黄山松群落呈现衰退趋势。研究戴云山黄山松林土壤有机碳组分沿海拔梯度的变化情况,不仅可以为该区域碳库估算提供科学依据,而且有助于揭示影响黄山松生长变化的机理。因此,选取戴云山不同海拔1300 m (L)、1450 m (M)和1600 m (H)]梯度的黄山松林,对其土壤基本理化性质、有机碳组分及微生物特征进行测定和分析。研究发现,海拔梯度下土壤养分含量呈先升高后降低的变化趋势,土壤碳组分含量与其变化一致,且微生物生物量碳和微生物生物量氮均在M海拔处最高,海拔梯度对碳水解酶没有显著影响。冗余分析表明,总氮是影响土壤有机碳变化的最主要因素,其次是碳氮比。因此在海拔跨度不大的情况下,土壤有机碳动态可能主要受氮素而非温度的影响。高海拔地区土壤惰性碳占比高,未来可能会持续加剧该地区黄山松的生长困境,使该区域碳库受到影响。

Elevation gradient characteristics and impact factors of soil carbon fractions in the Pinus taiwanensis Hayata forests of Daiyun Mountain

The elevation gradient may affect soil organic matter through a variety of environmental factors. The soil organic carbon pool is an important component of soil organic matter; its any slight changes may have an extremely important impact. Therefore, there may be variations in the soil carbon pool at different elevations. Soil organic carbon is an important indicator of soil fertility, which is affected by various factors, including soil physical and chemical properties and microorganisms. Pinus taiwanensis Hayata, which is an excellent tree species for afforestation and timber in high mountain areas, has recently experienced a decline in the high altitudes of Daiyun Mountain Nature Reserve. A study of the change in soil organic carbon fractions along the elevation gradient in the P. taiwanensis forests of Daiyun Mountain Nature Reserve can therefore not only provide a scientific basis for estimation of the carbon pool in this region, but also can help to elucidate the mechanisms influencing the growth and change in the dynamics of the P. taiwanensis forest. Therefore, in this study, the P. taiwanensis forests of Daiyun Mountain along different elevation at 1300 m (L), 1450 m (M), and 1600 m (H) were analyzed for the basic physicochemical properties, organic carbon fractions, and microbial characteristics of the soil. Our results showed that the soil nutrient content first increased and then decreased along the elevation gradient, and was consistent with the trends in the soil carbon fractions. The microbial biomass carbon and microbial biomass nitrogen were both the highest at M altitude (1450 m), and the elevation gradient had no significant effect on carbon hydrolase. A redundancy analysis showed that total nitrogen was the most important factor that affected the change in soil organic carbon, followed by the carbon/nitrogen ratio. Therefore, in the case of a small elevation span, it was mainly nitrogen, rather than temperature, that affected the change in soil organic carbon. The high-altitude area with a high recalcitrant carbon pool ratio may aggravate the growth dilemma of the P. taiwanensis forests in this area in the future, thereby affecting the carbon pool in this region.