湘中丘陵区4种植被类型土壤全磷、有效磷含量的变异特征

Variation characteristics of soil total phosphorus and effective phosphorus concentrations in four vegetation type soils in the central hilly area of Hunan Province, China

为揭示中亚热带植被恢复对土壤磷(P)有效性的影响机制,在湘中丘陵区选取了地域毗邻、环境(土壤、气候)条件基本一致、处于不同植被恢复阶段的4种植物群落——檵木-南烛-杜鹃灌草丛(LVR)、檵木-杉木-白栎灌木林(LCQ)、马尾松-柯(又名石栎)-檵木针阔混交林(PLL)以及柯-红淡比-青冈常绿阔叶林(LAG)为研究对象,设置固定样地,按0～10、10～20,20～30,30～40 cm分层采集土壤样品,测定不同季节土壤全磷(TP)和有效磷(AP)含量,比较研究不同植被类型土壤TP、AP含量的差异及其季节变化特征。结果表明:1)不同植被类型同一土层TP含量在各季节总体上随着植被恢复而增加,且LAG与LCQ、LVR(除夏季外)差异显著;季节变化也基本一致,除LAG 0～10 cm土层外,均表现为"夏高冬低(或秋低)型"。2)不同植被类型同一季节同一土层AP含量夏、冬季差异较大,而春、秋季较小,不同植被类型同一土层AP含量在各季节的变化不完全随着植被恢复而逐渐增加;但同一土层AP的季节平均含量基本上随着植被恢复而增加,同一植被类型不同土层AP含量的季节变化不尽相同。3)土壤TP、AP含量与群落总生物量、地上部分生物量、根系生物量、凋落物层现存量、土壤粘粒百分含量、有机碳含量、全N含量呈极显著的正相关关系,与土壤pH值呈显著的负相关关系。4)不同植被类型群落生物量、土壤粘粒百分含量、有机碳含量、全N含量、pH值的差异显著影响土壤TP、AP的含量。

In order to reveal the influence mechanism of vegetation restoration on the availability of soil phosphorus (P) in the subtropical regions, China, four kinds of plant community were selected as the study objects in central hilly area of Hunan Province, China, which adjacent to each other, had same environment conditions, and were at different stages of vegetation restoration, and which respectively were: Loropetalum chinense-Vaccinium bracteatum-Rhododendron mariesii scrub-grass-land (LVR), Loropetalum chinense- Cunninghamia lanceolata-Quercus fabri shrubbery (LCQ), Pinus massoniana-Lithocarpus glaber-Loropetalum chinense coniferousbroad leaved mixed forest (PLL) and Lithocarpus glaber-Cleyera japonica-Cyclobalanopsis glauca evergreen broad-leaved forest (LAG). Permanent plots were established in each vegetation communities. Soil samples were collected in layers of 0-10, 10-20, 20-30, 30-40 cm. The contents of total phosphorus (TP) and available phosphorus (AP) in soil in different seasons were determined, and the differences and seasonal characteristics of TP and AP contents in soil in different vegetation types were compared. The results showed that: 1) TP concentrations in the same soil layer in different forests type increased with the vegetation restoration, and there were significantly different between LAG and LCQ, LVR (except for summer) in the various seasons;The seasonal variation of TP concentrations were alsobasically consistent, and all showed significantly higher in the summer than in the winter or autumn except for LAG 0-10 cm soil layer. 2) Concentrations of AP in the same soil layer varied greatly in summer and winter with different vegetation types in the same season, but less in spring and autumn. And the change of AP concentrations in the same soil layer of different vegetation types in the same season did not increase gradually with vegetation restoration;however, the seasonal average concentration of AP in the same soil layer basically increased with vegetation restoration, and the seasonal variation of AP concentrations in different soil layers of the same vegetation type were different. 3) Significant-positive correlations were found between soil TP, AP and community biomass, aboveground biomass, root biomass, standing litter crops, soil clay perentage, organic carbon concent, total N, but significant-negative correlation with pH. 4) The findings indicated that the differences of community biomass, soil clay percentage, soil organic content, total N content, pH value in different forests type significantly affected on concentrations of soil TP and AP.