Lu Senbao, Chen Yunming, Sardans Jordi, Peñuelas Josep
Pomology Institute, Shanxi Agricultural University, Taiyuan, Shanxi, China.
The Research Center of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling, Shaanxi, China.
Front Plant Sci. 2025 May 13;16:1527930. doi: 10.3389/fpls.2025.1527930. eCollection 2025.
Mixed-species reforestation/afforestation has been a common practice for improving ecosystem nutrient sustainability. In the Loess Hilly Region, however, it remains unclear whether the mixture of dinitrogen (N)-fixing species with economic species and can improve nutrient concentrations of green and senescent leaves and their nutrient resorption. In 2022, we analyzed N and phosphorus (P) concentrations in green (GLNC, GLPC) and senescent leaves (SLNC, SLPC), resorption efficiencies (NRE and PRE), and relative resorption efficiency (RRE) in mixtures of × and × and monocultures of three species, considering tree structure and topsoil (0-20 cm) properties. One-way ANOVA followed by Tukey's test showed that senescent leaves nutrient concentrations for and Student's t test that green and senescent leaves of and were significantly greater in mixed stands than monocultures. Based on the same statistical methods, NRE and PRE of varied; those of and were significantly lower in mixed stands than monocultures. Additionally, RRE was < 100% for , but > 100% for and ; NRE and PRE was significantly positively associated in and all species. The correlation analysis demonstrated that crown area were significantly positively correlated with N and P concentrations of green and senescent leaves but negatively correlated with NRE and PRE for and , however, they were unrelated for and all species. Further, a random forest model analysis showed that soil available P was main factor driving GLNC for individual rather than all species. Within each species, linear regression analysis revealed that NRE was significantly negatively correlated with SLNC; for and , NRE and PRE were significantly negatively correlated with SLNC and SLPC, respectively. In contrast, the PRE of all species was significantly negatively correlated with GLPC but positively correlated with SLPC. Overall, the results suggested that tree mixture increased N and P cycling more in and than in , in the plant-soil system.
混交造林/植树造林一直是提高生态系统养分可持续性的常见做法。然而，在黄土丘陵区，固氮树种与经济树种的混合是否能提高绿叶和衰老叶片的养分浓度及其养分再吸收尚不清楚。2022年，我们分析了×和×混合物以及三种树种纯林中绿色（GLNC、GLPC）和衰老叶片（SLNC、SLPC）中的氮（N）和磷（P）浓度、再吸收效率（NRE和PRE）以及相对再吸收效率（RRE），同时考虑了树木结构和表土（0-20厘米）性质。单因素方差分析后进行Tukey检验表明，和衰老叶片的养分浓度，以及Student's t检验表明，和的绿叶和衰老叶片在混交林中显著高于纯林。基于相同的统计方法，的NRE和PRE有所不同；和的NRE和PRE在混交林中显著低于纯林。此外，的RRE<100%，但和的RRE>100%；和所有物种的NRE和PRE显著正相关。相关性分析表明，冠幅面积与绿叶和衰老叶片的N和P浓度显著正相关，但与和的NRE和PRE负相关，然而，它们与和所有物种无关。此外，随机森林模型分析表明，土壤有效磷是驱动个体而非所有物种GLNC的主要因素。在每个物种中，线性回归分析表明，NRE与SLNC显著负相关；对于和，NRE和PRE分别与SLNC和SLPC显著负相关。相比之下，所有物种的PRE与GLPC显著负相关，但与SLPC正相关。总体而言，结果表明，在植物-土壤系统中，树木混交在和中比在中增加了更多的N和P循环。
