Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China.
Key Laboratory of Soil Ecology and Health in Universities of Yunnan Province, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
Sci Total Environ. 2022 Nov 10;846:157456. doi: 10.1016/j.scitotenv.2022.157456. Epub 2022 Jul 19.
High atmospheric nitrogen (N) deposition and low soil phosphorus (P) availability occur simultaneously in tropical areas, and thus tropical plants need to adapt nutrient-use strategies to maintain growth and survival. Therefore, identifying the adaptative strategies of tropical plants at different successional stages under low soil P availability is indispensable. Here, we separately investigated foliar traits, photosynthetic characteristics, and P fractions of 8 species in the primary and secondary tropical forests after 10 years of N and P fertilization. P addition increased foliar P concentrations and deceased N:P ratio in the primary forest and secondary forest. The foliar photosynthetic rates did not significantly respond to nutrient additions, and the foliar photosynthetic P-use efficiency (PPUE) reduced under the P addition in the primary forest. In contrast, the foliar photosynthetic rates and photosynthetic nitrogen (N)-use efficiency (PNUE) were enhanced with nutrient additions in the secondary forest. The allocations of foliar nucleic acid P and residual P were reduced by P addition in the primary forest, whereas the allocation of metabolic P was enhanced and the allocation of residual P was reduced by P addition in the secondary forest. Additionally, a higher proportion of structural P was found in the primary forest, and a higher proportion of metabolic P was observed in the secondary forest. Interesting, structural equation model analysis revealed that the plants decreased the allocation of foliar nucleic acid P and increased the allocation of structural P in the primary forest, thereby reducing photosynthetic rates. Whereas the plants enhanced photosynthetic rates by promoting PPUE and the allocation of foliar metabolic P in the secondary forest. Our findings highlighted tropical plants at different successional stages can reasonably allocate foliar P to regulate photosynthetic rates and acclimate to low P environments.
高大气氮（N）沉积和低土壤磷（P）有效性同时发生在热带地区，因此热带植物需要适应养分利用策略以维持生长和生存。因此，确定低土壤 P 有效性下不同演替阶段热带植物的适应性策略是必不可少的。在这里，我们分别研究了经过 10 年 N 和 P 施肥后原生和次生热带森林中 8 个物种的叶片特征、光合作用特征和 P 分数。P 添加增加了原生林和次生林的叶片 P 浓度并降低了 N：P 比。叶片光合速率对养分添加没有显著响应，并且在原生林中添加 P 会降低叶片光合 P 利用效率（PPUE）。相比之下，次生林中添加养分会增强叶片光合速率和光合氮（N）利用效率（PNUE）。在原生林中，P 添加降低了叶片核酸 P 和残余 P 的分配，而次生林中，代谢 P 的分配增加，残余 P 的分配减少。此外，在原生林中发现了更高比例的结构 P，而在次生林中发现了更高比例的代谢 P。有趣的是，结构方程模型分析表明，植物在原生林中减少叶片核酸 P 的分配，增加结构 P 的分配，从而降低光合速率。而在次生林中，植物通过提高 PPUE 和叶片代谢 P 的分配来提高光合速率。我们的研究结果强调了不同演替阶段的热带植物可以合理分配叶片 P 来调节光合速率并适应低 P 环境。
