Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

Assisted population migration (APM) is the intentional movement of populations within a species range to sites where future environmental conditions are projected to be more conducive to growth. APM has been proposed as a proactive adaptation strategy to maintain forest productivity and to reduce the vulnerability of forest ecosystems to projected climate change. The validity of such a strategy will depend on the adaptation capacity of populations, which can partially be evaluated by the ecophysiological response of different genetic sources along a climatic gradient. This adaptation capacity results from the compromise between (i) the degree of genetic adaptation of seed sources to their environment of origin and (ii) the phenotypic plasticity of functional trait which can make it possible for transferred seed sources to positively respond to new growing conditions. We examined phenotypic variation in morphophysiological traits of six seed sources of white spruce (Picea glauca [Moench] Voss) along a regional climatic gradient in Québec, Canada. Seedlings from the seed sources were planted at three forest sites representing a mean annual temperature gradient of 2.2 °C. During the second growing season, we measured, height growth (H2014) and traits related to resources use efficiency and photosynthetic rate (Amax). All functional traits showed an adaptive response to the climatic gradient. Traits such as H2014, Amax, stomatal conductance (gs), the ratio of mesophyll to stomatal conductance, water use efficiency and photosynthetic nitrogen-use efficiency showed significant variation related to both physiological plasticity related to test site, and seed source variation related to local genetic adaptation. However, the amplitude of seed source variation was much less than that related to plantation sites in the area investigated. The six seed sources presented a similar level of physiological plasticity. H2014, Amax and gs, but not carboxylation capacity (Vcmax), were correlated and decreased with a reduction of the average temperature of the growing season at seed origin. The clinal variation in H2014 and Amax appeared to be driven by CO2 conductance. The presence of locally adapted functional traits suggests that the use of assisted population migration may have advantages for optimizing seed source productivity in future local climates

Knowledge of thermal acclimation of physiological processes of boreal tree species is necessary to determine their ability to adapt to predicted global warming and reduce the uncertainty around the anticipated feedbacks of forest ecosystems and global carbon cycle to climate change. The objective of this work was to examine the extent of thermal acclimation of net photosynthesis (A_n) and dark respiration (R_d) of two distant white spruce (Picea glauca) seed sources (from south and north of the commerial forest zone in Québec) in response to latitudinal and seasonal variations in growing conditions. The temperature responses of A_n, its biochemical and biophysical limitations, and R_d were measured in 1-year-old needles of seedlings from the seed sources growing in eight forest plantations along a regional thermal gradient of 5.5 °C in Québec, Canada. The average optimum temperature (T_opt) for A_n was 19 ± 1.2 °C and was similar among seed sources and plantation sites along the thermal gradient. Net photosynthesis at T_opt (A_opt) varied significantly among plantation sites and was quadratically related to the mean July temperature (MJT) of plantation sites. T_opt for mesophyll conductance, maximum electron transport rate and maximum rate of carboxylation were 28, 22 and 30 °C, respectively. Basal respiration rate (R_d at 10 °C) was linearly and negatively associated with MJT. Q₁₀ of R_d (the rate of change in R_d with a 10 °C increase in temperature) did not show any significant relationship with MJT and averaged 1.5 ± 0.1. The two seed sources were similar in their thermal responses to latitudinal and seasonal variations in growing conditions. The results showed moderate thermal acclimation of respiration and no evidence for thermal acclimation of photosynthesis or local genetic adaptation for traits related to thermal acclimation. Therefore, growth of local white spruces may decline in future climates.

Purpose of Review: Assisted migration is increasingly proposed as a proactive management strategy to mitigate the consequences of maladaptation predicted under climate change. Exploring the social and academic structure of the field, its research gaps, and future research directions can help further the understanding and facilitate the implementation of assisted migration strategies. Here we used bibliometric analysis to examine the intellectual, social, and conceptual structures of assisted migration research to identify gaps and opportunities for future research. Bibliometric data based on publications on assisted migration were collected from Scopus and Web of Science databases using assisted migration and climate change or their synonyms as queries. Metadata were merged, processed and several networks were constructed.Recent Findings: Co-citation and keyword co-occurrence networks identified three major clusters focused on (i) theory and risk of assisted migration of threatened and endangered species, (ii) impact of climate change on realized and fundamental climate and geographic niches, and (iii) assisted population migration. Collaboration network analysis identified three social core hubs: North America, Europe, and Australia, with the USA and Canada being the most productive and the most collaborative countries.Summary: We conclude that future research is expected to concern mainly the assessment of physiological response of species and populations to extreme climate events such as drought and frost, and the contribution of non-climatic factors and biotic interactions in local adaptation and population performance under climate change. Social core hubs distinguished in this work can be used to identify potential international research and training collaborators necessary to address gaps and challenges underlying assisted migration implementation.

Global warming is predicted to extend the growing season of trees and plants, and advance spring phenology. However, intensification of extreme climate events in mid-latitude forests, from weakening of the jet stream and atmospheric blockings, may expose trees to increased risk associated with more frequent late-spring frosts. Still, little is known regarding the intraspecific variation in frost tolerance and how it may be shaped by local adaptation to the climate of seed origin. As part of an assisted migration trial located in different bioclimatic zones in the province of Quebec, Canada, and following an extensive late-spring frost that occurred at the end of May 2021, we evaluated the frost damages on various white spruce (Picea glauca) seed sources tested on three sites (south, central, and north). The severity of frost damages was assessed on 5,376 trees after the cold spell and an early spring warming which advanced bud flush by approximately 10 days on average. The frost damage rate was similar among sites and seed sources and averaged 99.8%. Frost damage severity was unrelated to the latitude of seed origin but was variable among sites. The proportion of severely damaged trees was higher in the northern site, followed by central and southern sites. The proportion of severely damaged trees was linearly and inversely related to tree height before the frost event. Apical growth cancelation was not significantly different among seed sources including local ones, and averaged 74, 46, and 22%, respectively, in central, northern, and southern plantation sites. This study provides recommendations to limit the loss of plantation productivity associated with such a succession of spring climate anomalies. Implications for seed transfer models in the context of climate change and productivity of spruce plantations are discussed in the light of lack of local adaptation to such pronounced climate instability and ensuing large-scale maladaptation.

The increased use of fertilizers in agriculture and forest and horticulture nurseries contributes to the pollution of water resources and greenhouse gas emissions. The objective of this study is to evaluate a new generation of fertilizers coated with new biodegradable polymers in terms of physical quality, release kinetics, and their effect on reducing nitrate leaching and N₂O emissions and compare them to uncoated fertilizers (Urea, monoammonium phosphate (MAP), and KCl) having the same mineral nutrient concentration. In a peat-based substrate, the release of mineral nutrients was similar in both types of fertilizer. Two hours after application, Urea released 34% more urea than Biodrix N, the difference disappearing after one day. The leaching of cumulative ammonium nitrogen after 20 days was reduced by 40% and 26% respectively by Aminaex and Biodrix N compared to Urea. In a peat-based substrate containing 30% (v/v) of compost, the cumulative nitrate leaching was reduced by 54% by Biodrix N and by 41% by Aminaex compared to Urea. The highest average N₂O flux was observed on the first day for Urea, whereas for Aminaex and Biodrix N, N₂O emissions increased on the third day, reaching a peak of efflux on day 10. A 10-day delay of the N₂O efflux emissions and a longer period of emissions were observed in treatments containing Aminaex and Biodrix N compared to Urea. Cumulative N₂O efflux was 142, 154, and 171 mg m⁻², respectively, for Urea, Aminaex, and Biodrix N over a 20-day period. These new biodegradable polymer-coated nitrogen fertilizers can reduce mineral nutrient leaching in the event of heavy rainfall and lower maximum N₂O emissions in comparison with conventional nitrogen sources.