Genetic trials improve the transfer of Douglas‐fir distribution models across continents

Abstract

Climate change is likely to result in novel conditions with no analogy to current climate. Therefore, the application of species distribution models (SDMs) based on the correlation between observed species’ occurrence and their environment is questionable and calls for a better understanding of the traits that determine species occurrence. Here, we compared two intraspecific, trait‐based SDMs with occurrence‐based SDMs, all developed from European data, and analyzed their transferability to the native range of Douglas‐fir in North America. With data from 50 provenance trials of Douglas‐fir in central Europe multivariate universal response functions (URFs) were developed for two functional traits (dominant tree height and basal area) which are good indicators of growth and vitality under given environmental conditions. These trials included 290 North American provenances of Douglas‐fir. The URFs combine genetic effects i.e. the climate of provenance origin and environmental effects, i.e. the climate of planting locations into an integrated model to predict the respective functional trait from climate data. The URFs were applied as SDMs (URF‐SDMs) by converting growth performances into occurrence. For comparison, an ensemble occurrence‐based SDM was developed and block cross validated with the BIOMOD2 modeling platform utilizing the observed occurrence of Douglas‐fir in Europe. The two trait based SDMs and the occurrence‐based SDM, all calibrated with data from Europe, were applied to predict the known distribution of Douglas‐fir in its introduced and native range in Europe and North America. Both models performed well within their calibration range in Europe, but model transfer to its native range in North America was superior in case of the URF‐SDMs showing similar predictive power as SDMs developed in North America itself. The high transferability of the URF‐SDMs is a testimony of their applicability under novel climatic conditions highlighting the role of intraspecific trait variation for adaptation planning in climate change.

Range-wide variation in local adaptation and phenotypic plasticity of fitness-related traits in Fagus sylvatica and their implications under climate change

“…Our analysis of species occurrence as a function of spatial trait values also suggests that a combination of these traits contributes differently to the delimitation of the species range (Table 3), in particular: (i) mortality delimits certain parts of the southern and eastern range of beech, reflecting the climatic marginality of the species in these areas, and meaning that these populations are most threatened and making eastwards expansion of beech difficult (although more studies on regeneration are needed to confirm this result); this is the case for many species whose highest mortality is in the driest part of their range (Anderegg et al, 2015; Benito-Garzón et al, 2013; Camarero, Gazol, Sancho-Benages, & Sangüesa-Barreda, 2015); (ii) the smallest girths are predicted in the southern part of the distribution and the eastern part of the range, suggesting that radial growth is mostly restricted by drought (interaction graph and map, Figure 1b), as has already been pointed out (Farahat & Linderholm, 2018); (iii) with very little variation across climatic gradients, vertical growth alone will not delimit beech range. This is not the case for other tree species, for which tree height is clearly delimiting species range (Chakraborty, Schueler, Lexer, & Wang, 2018), highlighting the fact that no single best trait delimits tree species ranges; (iv) projections of trees growing in southern and south-eastern regions that flush early also have higher mortality and lower growth predictions than elsewhere within the species range. However, when tree height and leaf flushing are pooled together in the two-trait model, this leads to an decrease in vertical growth in the North; (v) it seems that in beech, and likely in other species with local adaptation to photoperiod, phenology could restrict the northern expansion of ranges (Duputié et al, 2015; Saltré, Duputié, Gaucherel, & Chuine, 2015), although the link between phenology, survival and fitness is still unclear, and more experiments are needed to better understand the interaction between photoperiod and phenology.…”

ΔTraitSDMs: species distribution models that account for local adaptation and phenotypic plasticity

“…Because traits and their relation with fitness can change across climatic gradients, projections are highly dependent on the trait used. In some cases, higher values of fitness‐related traits correspond to species occurrence (Benito Garzón et al ., ; Chakraborty et al ., ), but in other cases species occurrence is explained by the complex relationship among various traits over the species range (Gárate Escamilla et al ., ). For example, phenological traits might delimit species ranges at high latitudes, at least for those species in which photoperiod actively constrains phenology (Way & Montgomery, ).…”

A transnational cooperation for sustainable use and management of non-native trees in urban, peri-urban and forest ecosystems in the Alpine region (ALPTREES)

“…Franco) are being valued for their perceived suitability to adapt European forests to CC (Vitali et al 2017) and their cultivation will likely be intensified in the future. Douglas fir has been discussed as an alternative tree species for Norway spruce (Picea abies) especially at low elevations in Central Europe (Roques et al 2019, Klimo andHager 2000, Roloff andGrundmann 2006) due to their drought tolerance and superior productivity (Chakraborty et al 2015, Chakraborty et al 2018. Many NNT species have a long history of cultivation in Europe such as the Douglas-fir .…”