Contrasting growth forecasts across the geographical range of Scots pine due to altitudinal and latitudinal differences in climatic sensitivity

Abstract

Ongoing changes in global climate are altering ecological conditions for many species. The consequences of such changes are typically most evident at the edge of a species' geographical distribution, where differences in growth or population dynamics may result in range expansions or contractions. Understanding population responses to different climatic drivers along wide latitudinal and altitudinal gradients is necessary in order to gain a better understanding of plant responses to ongoing increases in global temperature and drought severity. We selected Scots pine (Pinus sylvestris L.) as a model species to explore growth responses to climatic variability (seasonal temperature and precipitation) over the last century through dendrochronological methods. We developed linear models based on age, climate and previous growth to forecast growth trends up to year 2100 using climatic predictions. Populations were located at the treeline across a latitudinal gradient covering the northern, central and southernmost populations and across an altitudinal gradient at the southern edge of the distribution (treeline, medium and lower elevations). Radial growth was maximal at medium altitude and treeline of the southernmost populations. Temperature was the main factor controlling growth variability along the gradients, although the timing and strength of climatic variables affecting growth shifted with latitude and altitude. Predictive models forecast a general increase in Scots pine growth at treeline across the latitudinal distribution, with southern populations increasing growth up to year 2050, when it stabilizes. The highest responsiveness appeared at central latitude, and moderate growth increase is projected at the northern limit. Contrastingly, the model forecasted growth declines at lowland-southern populations, suggesting an upslope range displacement over the coming decades. Our results give insight into the geographical responses of tree species to climate change and demonstrate the importance of incorporating biogeographical variability into predictive models for an accurate prediction of species dynamics as climate changes.

Geographical adaptation prevails over species‐specific determinism in trees’ vulnerability to climate change at Mediterranean rear‐edge forests

“…Rear‐edge beech and Scots pine forests displayed a higher proportion of declining growth trends than the rest of species. However, we also found some forests displaying significant increasing growth trends during the last decades, which is not unprecedented at the rear edge (Di Filippo et al, ; Galván, Camarero, Ginzler, & Buentgen, ; Gazol et al, ; Matías et al, ). In our particular case, most of the positive growth trends were located in the centre and east of the Mediterranean Basin and linked to sites under cooler and moister climate conditions and lower marginality indices (i.e., less climatically marginal).…”

“…Previous studies reporting broad‐scale declining growth patterns in the peri‐Mediterranean region usually describe a generalized positive influence of summer precipitation on tree growth and a less homogeneous negative influence of summer temperature, pointing to generalized seasonal water limitation (e.g., Cavin & Jump, ; Dorado‐Liñán, Zorita, et al, ; Gazol et al, ; Hacket‐Pain et al, ; Jung et al, ; Matías et al, ; Sánchez‐Salguero et al, ). We also found a more generalized positive effect of summer precipitation than negative effects of summer temperature across sites.…”

“…Several studies have described a determinant influence of winter and early spring temperatures on distribution and growth of both conifers (Gea‐Izquierdo et al, ; Matías et al, ; Sánchez‐Salguero et al, ) and broadleaf deciduous species (Gea‐Izquierdo & Cañellas, ; Vitasse et al, ; Vitasse, Lenz, & Körner, ) close to the rear edge. We did find a significant influence of spring climate on growth in our multispecies forests network.…”

The climatic drivers of primary Picea forest growth along the Carpathian arc are changing under rising temperatures

“…Summer temperatures generally dictate enzyme kinetics and cell division rates in cold climates (e.g. This constraint on wood formation declines gradually toward warmer climate regimes (e.g., Babst et al, 2013;Mäkinen et al, 2003;Matías et al, 2017). This constraint on wood formation declines gradually toward warmer climate regimes (e.g., Babst et al, 2013;Mäkinen et al, 2003;Matías et al, 2017).…”

“…Radial tree growth at high latitudes and altitudes is typically limited by low temperatures and short growing seasons, while growth at low latitudes and altitudes is limited by moisture (e.g., Babst et al, 2013;Mäkinen et al, 2002). Improving our understanding of regional climate change responses requires extensive sampling along climatic gradients (Galván, Camarero, & Gutiérrez, 2014;Holz, Hart, Williamson, Veblen, & Aravena, 2018;de Luis et al, 2013) and a greater emphasis on absolute growth increments over the exclusive analyses of detrended ring width series (Matías, Linares, Sánchez-Miranda, & Jump, 2017). Furthermore, responses of tree growth to climate change vary along climatic gradients and dynamic vegetation models disagree on where growth responses are expected to be positive or negative .…”