Xu Yaowen, Ge Xiaogai, Zhou Benzhi, Lei Lei, Xiao Wenfa
Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, China.
Qianjiangyuan Forest Ecosystem Research Station, National Forestry and Grassland Administration of China, Hangzhou, China.
Front Plant Sci. 2022 Aug 1;13:939683. doi: 10.3389/fpls.2022.939683. eCollection 2022.
Phosphorus (P) is a nutrient limiting plant growth in subtropical regions. However, our understanding of how soil P responds to an increase in stand age is rather poor. In particular, little is known about how bioavailable P pools (soluble P, exchangeable P, hydrolyzable P, and ligand P) shift with a change in stand age. Moreover, the P cycle in rhizosphere soil has the most direct and significant influence on plants. The aim of the present study was to determine the concentrations of total P in various rhizosphere soil bioavailable P fractions in 5-, 9-, 19-, 29-, and 35-year-old stands of Lamb. According to the results, total P (TP) concentration and N:P ratio in rhizosphere soil first decreased, and then increased with an increase in stand age. Soluble P concentration decreased first, and then increased with an increase in stand age; exchangeable P and ligand P decreased first, and then tended to be stable with an increase in stand age, whereas hydrolyzable P increased first, and then decreased. Structural Equation Model results suggested that ligand P and soluble P were the major factor affecting the TP. In addition, soil microorganisms and acid phosphatase-driven hydrolyzable P play a crucial role in soil bioavailable P cycling. Overall, the results of our study provide a mechanistic understanding of soil bioavailable P cycling under low available P conditions, and a basis for an effective P management strategy for the sustainable development of plantations.
磷（P）是亚热带地区限制植物生长的一种养分。然而，我们对土壤磷如何响应林分年龄增加的了解相当有限。特别是，关于生物可利用磷库（可溶性磷、交换性磷、可水解磷和配体磷）如何随林分年龄变化而变化知之甚少。此外，根际土壤中的磷循环对植物具有最直接和显著的影响。本研究的目的是测定5年、9年、19年、29年和35年生羊草（Lamb.）林分根际土壤中各种生物可利用磷组分的总磷浓度。结果表明，根际土壤中的总磷（TP）浓度和氮磷比随林分年龄增加先降低后升高。可溶性磷浓度先降低后升高；交换性磷和配体磷先降低，然后随林分年龄增加趋于稳定，而可水解磷先升高后降低。结构方程模型结果表明，配体磷和可溶性磷是影响总磷的主要因素。此外，土壤微生物和酸性磷酸酶驱动的可水解磷在土壤生物可利用磷循环中起着关键作用。总体而言，我们的研究结果为低有效磷条件下土壤生物可利用磷循环提供了机理认识，并为人工林可持续发展的有效磷管理策略提供了依据。
