Yu Lei, Dong Haojie, Huang Zongdi, Korpelainen Helena, Li Chunyang
Department of Ecology, College of Life and Environmental Sciences, Hangzhou Normal University, Yuhangtang Road 2318, Hangzhou 311121, China.
Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, PO Box 27, Latokartanonkaari 5 FI-00014, Helsinki, Finland.
Tree Physiol. 2021 Nov 8;41(11):2082-2095. doi: 10.1093/treephys/tpab054.
The continuously increasing atmospheric carbon dioxide concentration ([CO2]) has substantial effects on plant growth, and on the composition and structure of forests. However, how plants respond to elevated [CO2] (e[CO2]) under intra- and interspecific competition has been largely overlooked. In this study, we employed Abies faxoniana Rehder & Wilson and Picea purpurea Mast. seedlings to explore the effects of e[CO2] (700 p.p.m.) and plant-plant competition on plant growth, physiological and morphological traits, and leaf ultrastructure. We found that e[CO2] stimulated plant growth, photosynthesis and nonstructural carbohydrates (NSC), affected morphological traits and leaf ultrastructure, and enhanced water- and nitrogen (N)- use efficiencies in A. faxoniana and P. purpurea. Under interspecific competition and e[CO2], P. purpurea showed a higher biomass accumulation, photosynthetic capacity and rate of ectomycorrhizal infection, and higher water- and N-use efficiencies compared with A. faxoniana. However, under intraspecific competition and e[CO2], the two conifers showed no differences in biomass accumulation, photosynthetic capacity, and water- and N-use efficiencies. In addition, under interspecific competition and e[CO2], A. faxoniana exhibited higher NSC levels in leaves as well as more frequent and greater starch granules, which may indicate carbohydrate limitation. Consequently, we concluded that under interspecific competition, P. purpurea possesses a positive growth and adjustment strategy (e.g. a higher photosynthetic capacity and rate of ectomycorrhizal infection, and higher water- and N-use efficiencies), while A. faxoniana likely suffers from carbohydrate limitation to cope with rising [CO2]. Our study highlights that plant-plant competition should be taken into consideration when assessing the impact of rising [CO2] on the plant growth and physiological performance.
大气中二氧化碳浓度（[CO₂]）持续上升对植物生长以及森林的组成和结构产生了重大影响。然而，在种内和种间竞争条件下植物如何响应升高的[CO₂]（e[CO₂]）在很大程度上被忽视了。在本研究中，我们利用岷江冷杉（Abies faxoniana Rehder & Wilson）和紫果云杉（Picea purpurea Mast.）幼苗来探究e[CO₂]（700 ppm）和植物间竞争对植物生长、生理和形态特征以及叶片超微结构的影响。我们发现，e[CO₂]促进了岷江冷杉和紫果云杉的植物生长、光合作用和非结构性碳水化合物（NSC）积累，影响了形态特征和叶片超微结构，并提高了水分和氮（N）利用效率。在种间竞争和e[CO₂]条件下，与岷江冷杉相比，紫果云杉表现出更高的生物量积累、光合能力和外生菌根感染率，以及更高的水分和N利用效率。然而，在种内竞争和e[CO₂]条件下，这两种针叶树在生物量积累、光合能力以及水分和N利用效率方面没有差异。此外，在种间竞争和e[CO₂]条件下，岷江冷杉叶片中的NSC水平较高，淀粉颗粒更频繁且更大，这可能表明存在碳水化合物限制。因此，我们得出结论，在种间竞争下，紫果云杉具有积极的生长和适应策略（例如更高的光合能力、外生菌根感染率以及更高的水分和N利用效率），而岷江冷杉可能因碳水化合物限制而难以应对不断上升的[CO₂]。我们的研究强调，在评估升高的[CO₂]对植物生长和生理性能的影响时，应考虑植物间竞争因素。
