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The function of landscape plants on the ecosystem can alleviate environmental issues of urbanization and global change. Global changes due to elevated CO2 affect plant growth and survival, but there is a lack of quantitative methods to evaluate the adaptability of landscape plants to future climate conditions. Leaf traits characterized by leaf economic spectrum (LES) are the universal currency for predicting the impact on plant ecosystem functions. Elevated CO2 usually leads to photosynthetic acclimation (PC), characterised by decreased photosynthetic capacity. Here, we proposed a theoretical and practical framework for the use of LES and PC to project the potential performance of landscape plants under future climatic conditions through principal component analysis, structural equation modelling, photosynthetic restriction analysis and nitrogen allocation analysis. We used wintersweet (an important landscaping species) to test the feasibility of this framework under elevated CO2 and different nitrogen (N) supplies. We found that elevated CO2 decreased the specific leaf area but increased leaf N concentration. The results suggest wintersweet may be characterized by an LES with high leaf construction costs, low photosynthetic return, and robust stress resistance. Elevated CO2 reduced photosynthetic capacity and stomatal conductance but increased photosynthetic rate and leaf area. These positive physio‐ecological traits, e.g., larger leaf area (canopy), higher water use efficiency and stress resistance, may lead to improved performance of wintersweet under the predicted future climatic conditions. The results suggest planting more wintersweet in urban landscaping may be an effective adaptive strategy to climate change. [ABSTRACT FROM AUTHOR]

In response to global warming, trees are expected to shift their distribution ranges to higher latitudes. The range shift will expose them to novel environmental conditions, such as new photoperiod regimes. These factors can interact with rising atmospheric CO2 ([CO2]) to affect trees' physiology and growth. This study simulated future environmental conditions to investigate photosynthetic responses to changes in photoperiod regimes (seed origin [48°N], 52, 55, and 58°N) and [CO2] (ambient 400 vs. elevated 1000 μmol mol−1) in white birch (Betula papyrifera Marsh.) seedlings. Our results show that elevated [CO2] stimulated leaf photosynthesis (Pn) at the two lower latitudes (48 and 52°N). However, this stimulation by elevated [CO2] was lost in the two higher latitudes (55 and 58°N). Elevated [CO2] led to the downregulation of maximum Rubisco activity (Vcmax) for the two higher latitudes, and maximum electron transport rate (Jmax) and triose phosphate utilization (TPU) at 58°N, while it enhanced Jmax and TPU for the two lower latitudes. Increased instantaneous water‐use efficiency (IWUE) for the two lower latitudes was primarily attributed to the CO2 stimulation of Pn while the higher IWUE under the photoperiod regimes of 55 and 58°N latitudes was explained by reduced water loss. Photoperiod effects varied with [CO2]: Pn increased at the photoperiod regimes of 55 and 58°N in ambient [CO2] while it tended to decline under these photoperiods in elevated [CO2]. Our study suggests that the photosynthesis of white birch will likely respond negatively to northward migration or seed transfer in response to climate change. [ABSTRACT FROM AUTHOR]

Climate change will cause northward shifts of climate envelopes for boreal plants, however, the different photoperiod and soil moisture regimes at higher latitudes will likely influence the success of species migrations (natural and assisted). The objective of this study was to assess the effects of photoperiod regime and its interactions with soil moisture and carbon dioxide concentration ([CO2]) on the morpho-physiological processes in jack pine Pinus banksiana. One-year old seedlings were exposed to two [CO2] (400 and 950 μmol mol-1), two soil moistures (60-70% and 30-40% of field water capacity) and three photoperiod regimes (photoperiods at seed origin, 5° and 10° north of the seed origin) in environment controlled greenhouses. The impacts of photoperiod, soil moisture and elevated [CO2] on growth and physiological processes in the seedlings were examined. The results suggest that the response of jack pine to climate change will be complex under the interactive effects of northward migration associated longer photoperiod, soil moisture stress and elevated [CO2]. The longer photoperiod associated with higher latitudes under elevated [CO2] significantly advanced the budburst at both high and low soil moisture regimes, which may likely increase the risk of late spring frosts damage prior to and during budburst. The interactive effects of longer photoperiod and low soil moisture significantly increased the water use efficiency under elevated [CO2]. However, the significant 2- and 3-way interactions suggest that drought and longer photoperiods with northward migration will limit the positive effects of elevated [CO2] on growth and physiological processes in the species. These results might have important implications in assisted migration/seed transfer of the species following climate change. [ABSTRACT FROM AUTHOR]

White birch ( Betula papyrifera Marsh.) seedlings were exposed to ambient or doubled ambient carbon dioxide concentration ([CO2]), three soil temperatures ( Tsoil) (low, intermediate, high), and three phosphorus (P) regimes (low, medium, high) in environment-controlled greenhouses. Height ( H), root-collar diameter (RCD), biomass, and leaf phosphorus concentration (leaf P) were determined four months after initiation of treatments. The low Tsoil reduced H, RCD, shoot biomass, root biomass and total seedling biomass whereas the high-P level and the [CO2] elevation increased all the growth and biomass parameters. Elevated [CO2] significantly reduced leaf P. There were significant two-factor interactions suggesting that the effect of elevated [CO2] on (1) H, total biomass, biomass of plant components, and leaf P was dependent on Tsoil, (2) total biomass was contingent on P regime. For instance, the positive response of H and total biomass to elevated [CO2] was limited to seedlings raised under the intermediate and high Tsoil, respectively. In addition, [CO2] elevation increased total biomass only at the high-P regime but not at the low- or medium-P level where the effect of [CO2] was statistically insignificant. No significant main effect of treatment or interaction was observed for root to shoot biomass ratio. [ABSTRACT FROM AUTHOR]