Predicting species dominance shifts across elevation gradients in mountain forests in Greece under a warmer and drier climate

Abstract

The Mediterranean Basin is expected to face warmer and drier conditions in the future, following projected increases in temperature and declines in precipitation. The aim of this study is to explore how forests dominated by Abies borisii-regis, Abies cephalonica, Fagus sylvatica, Pinus nigra and Quercus frainetto will respond under such conditions. We combined an individual-based model (GREFOS), with a novel tree ring data set in order to constrain tree diameter growth and to account for inter-and intraspecific growth variability. We used wood density data to infer tree longevity, taking into account inter-and intraspecific variability. The model was applied at three 500-m-wide elevation gradients at Taygetos in Peloponnese, at Agrafa on Southern Pindos and at Valia Kalda on Northern Pindos in Greece. Simulations adequately represented species distribution and abundance across the elevation gradients under current climate. We subsequently used the model to estimate species and functional trait shifts under warmer and drier future conditions based on the IPCC A1B scenario. In all three sites, a retreat of less drought-tolerant species and an upward shift of more drought-tolerant species were simulated. These shifts were also associated with changes in two key functional traits, in particular maximum radial growth rate and wood density. Drought-tolerant species presented an increase in their average maximal growth and decrease in their average wood density, in contrast to less droughttolerant species.

Capturing ecological processes in dynamic forest models: why there is no silver bullet to cope with complexity

“…To obtain an empirically based kG parameterization, we analyzed >50,000 individual tree‐ring chronologies of 15 European species from the International Tree‐Ring Data Bank (ITRDB), surprisingly revealing that (1) the 15 species fell into merely two groups of maximum radial increment and (2) differences between species within each group were negligible (Appendix : Table S2): Species able to reach a height of at least ≈30 m are characterized by maximum ring‐width increments of ~10 mm/yr (99% percentile), while species with smaller maximum height reach maximum increments of ~5 mm/yr. These maximum values are in line with other empirical studies (Bragg 2001, Lee et al 2004, Fyllas et al 2017) and a later analysis based on a pan‐continental tree‐ring width database comprising mostly other species (Cailleret et al 2017; M. Cailleret, personal communication ). Thus, we fitted the kG parameter for every species so that maximum diameter increment (i.e., twice the maximum radial increment) under optimum conditions reached 20 or 10 mm/yr according to the group (Fig.…”

Trends of forest and ecosystem services changes in the Mescalero Apache Tribal Lands

“…The shift is also comparable with model projections of forest conversion and drought‐tolerant species shifting north and higher in elevation due to climate change worldwide (Fyllas et al. 2017, Shvidenko et al. 2017).…”

Stand‐scale climate change impacts on forests over large areas: transient responses and projection uncertainties

“…Thus, they account not only for climate‐induced direct effects, but also for indirect effects through changes in interspecific competition at the local scale (Snell et al 2014). Hence, these models provide a suitable framework for exploring forest dynamics across elevation gradients (e.g., Shuman et al 2014, Foster et al 2016, Fyllas et al 2017). Moreover, these models consider small‐scale forest stand characteristics (Lindner et al 1997), incorporate management functions (Rasche et al 2011) and account for small‐scale factors such as topography or soil properties (Shugart et al 2018).…”