State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, 311300, China; Science and Technology Research Institute of Zhejiang University of Technology in Ninghai County, Ninghai, 315600, China.
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, 311300, China.
Plant Physiol Biochem. 2021 May;162:150-160. doi: 10.1016/j.plaphy.2021.02.029. Epub 2021 Feb 25.
Nitrogen (N) deposition affects plant growth and interspecific interaction. This study aimed to explore the effect of N deposition on the growth and eco-physiological interactions between two tree species dominating in subtropical forests. A greenhouse experiment was conducted for 6 months in which the conifer Cunninghamia lanceolata and the broadleaved Phoebe chekiangensis were grown in monocultures and in a mixture under two levels of N addition: 0 and 45 kg ha yr. The plant growth, root architecture, biomass distribution, element contents in plants and soil, and photosynthetic physiology were determined. The height and crown width of both seedlings tended to be higher in the mixture than in the monoculture when grown without N addition. P. chekiangensis was superior to C. lanceolata in resource acquisition and showed a greater net photosynthetic rate, plant height, crown width, total biomass, and belowground biomass distribution. In the mixture, N addition increased the net photosynthetic rate and decreased the height, ground diameter, and crown width of both species. Belowground biomass distribution was decreased in C. lanceolata but increased in P. chekiangensis under N addition. The P contents in both seedlings were higher in the mixture than in monocultures. Results showed N addition aggravated the competition and weakened the growth of both species in the mixture, largely determined by the competition for resources through the changing root architecture and biomass allocation. Our results provide new insights into the mechanisms of interspecific interaction in response to increasing N deposition in silvicultural practice.
氮（N）沉降会影响植物的生长和种间相互作用。本研究旨在探索 N 沉降对两种在亚热带森林中占主导地位的树种生长和生态生理相互作用的影响。在温室中进行了为期 6 个月的实验，其中种植了针叶树杉木和阔叶树浙江楠，在两种施氮水平（0 和 45 kg ha yr）下进行了单种和混种。测定了植物生长、根系结构、生物量分布、植物和土壤中的元素含量以及光合作用生理特性。在不添加 N 的情况下，两种幼苗的高度和冠宽在混种中均高于单种。在资源获取方面，浙江楠优于杉木，具有更高的净光合速率、植物高度、冠宽、总生物量和地下生物量分布。在混种中，施 N 增加了净光合速率，降低了两种树种的高度、地径和冠宽。施 N 后，杉木的地下生物量分布减少，而浙江楠的地下生物量分布增加。两种幼苗的磷含量在混种中均高于单种。结果表明，N 沉降加剧了混种中两种树种之间的竞争，削弱了它们的生长，这主要是由根系结构和生物量分配的变化引起的资源竞争决定的。我们的研究结果为林学实践中应对增加的 N 沉降的种间相互作用机制提供了新的见解。
