中亚热带森林转换对土壤磷积累的影响

磷是植物生长的必需元素之一,是维持亚热带森林生态系统生产力的关键因子。研究森林转换后土壤因素对磷素的影响,对生态系统的稳定和森林经营具有重要意义。选取由亚热带常绿阔叶林转换而成的米槠次生林(SF)、米槠人促林(AR)和杉木人工林(CF)为研究对象,测定了土壤理化性质、铁铝氧化物、各形态磷含量以及酸性磷酸酶活性,旨在探究土壤磷对森林转换的响应和驱动土壤磷变化的影响因子。结果显示:米槠人促林土壤的全磷、有机磷和微生物生物量磷显著高于米槠次生林和杉木人工林;冗余分析(RDA)发现,土壤含水量、总氮和无定型铁是影响淋溶层土壤磷的主要因子,而在淀积层,则是酸性磷酸酶、游离型铁和总氮起主要作用;土壤生物化学属性和微生物特性都会影响着不同形态土壤P的积累,其中土壤中的水分和酸性磷酸酶活性是调控土壤磷的关键因子。研究表明,中亚热带地区天然林转换为人促更新林更有利于森林土壤磷的储存和供应,有助于维持本区域森林生态系统的稳定。

Effect of soil factors after forest conversion on the accumulation of phosphorus species in mid-subtropical forests

Phosphorus (P), a macro-nutrient essential for plant growth, is considered the key factor for maintaining the productivity of subtropical forest ecosystems. Understanding the effects of soil factors on the accumulation of phosphorus species after forest conversion is important in developing management practices that sustain and enhance ecosystem functionality. The objectives of the present study were to evaluate the response of soil phosphorus to forest conversion, and elucidate the mechanisms and environmental factors driving changes in soil phosphorus. The study sites included secondary broadleaved forests of Castanopsis carlesii (SF), human-assisted naturally regenerated forests of Castanopsis carlesii (AR), and plantations of Cunninghamia lanceolata (CF), which were converted from natural forests in the mid-subtropical region of China. Basic physicochemical characteristics, including iron and aluminum oxide content, different phosphorus forms, and acid phosphatase activities, were determined. The results revealed that the soil total P and organic and microbial biomass P levels were significantly higher in AR than in SF or CF. A redundancy analysis indicated that the changes in soil phosphorus were mainly driven by soil moisture, total nitrogen, and amorphous Fe oxides (Feo) in the eluvial horizon, and by acid phosphatase, free Fe (Fed), and total nitrogen in the illuvial horizon. The results suggest that soil biochemical properties and microbial characteristics affect the accumulation of different soil P formations, primarily by changing the soil moisture levels and acid phosphatase activity. In summary, human-assisted naturally regenerated forests converted from natural forests were the most conducive to the storage and supply of nutrients and the sustainable development of ecosystem functionality among the management systems studied. The present study might provide a theoretical basis for assessing forest management practices in mid-subtropical forests.