Search

Changes in climate can alter the distribution and population dynamics of tree species by altering their recruitment patterns, especially at range edges. However, geographical patterns of genetic diversity could buffer the negative consequences of changing climate at rear range edges where populations might also harbour individuals with drought-adapted genotypes. Silver fir (Abies alba Mill.) reaches its south-western distribution limit in the Spanish Pyrenees, where recent climatic dieback events have disproportionately affected westernmost populations. We hypothesized that silver fir populations from the eastern Pyrenees are less vulnerable to the expected changing climate due to the inclusion of drought-resistant genotypes. We performed an experiment under strictly controlled conditions simulating projected warming and drought compared with current conditions and analysed physiology, growth and survival of silver fir seedlings collected from eastern and western Pyrenean populations. Genetic analyses separated eastern and western provenances in two different lineages. Climate treatments affected seedling morphology and survival of both lineages in an overall similar way: elevated drought diminished survival and induced a higher biomass allocation to roots. Increased temperature and drought provoked more negative stem water potentials and increased δ13C ratios in leaves. Warming reduced nitrogen concentration and increased soluble sugar content in leaves, whereas drought increased nitrogen concentration. Lineage affected these physiological parameters, with western seedlings being more sensitive to warming and drought increase in terms of δ13C, nitrogen and content of soluble sugars. Our results demonstrate that, in A. alba, differences in the physiological response of this species to drought are also associated with differences in biogeographical history. [ABSTRACT FROM AUTHOR]

Scots pine recruitment is likely to change in response to climate variations. A recruitment reduction is expected at the southern edge and an expansion through northern range. However, local adaptations to drought of southern populations might modulate this declining trendOngoing changes in global climate are having a significant impact on the distribution of plant species, with effects particularly evident at range limits. We assessed the capacity of Pinus sylvestris L. populations at northernmost and southernmost limits of the distribution to cope with projected changes in climate. We investigated responses including seed germination and early seedling growth and survival, using seeds from northernmost (Kevo, Finland) and southernmost (Granada, Spain) populations. Seeds were grown under current climate conditions in each area and under temperatures increased by 5 °C, with changes in precipitation of +30% or –30% with reference to current values at northern and southern limits, respectively, in a fully factorial controlled-conditions experimental design. Increased temperatures reduced germination time and enhanced biomass gain at both range edges but reduced survival at the southern range edge. Higher precipitation also increased survival and biomass but only under a southern climate. Seeds from the southern origin emerged faster, produced bigger seedlings, allocated higher biomass to roots, and survived better than northern ones. These results indicate that recruitment will be reduced at the southernmost range of the species, whereas it will be enhanced at the northern limit, and that the southern seed sources are better adapted to survive under drier conditions. However, future climate will impose a trade-off between seedling growth and survival probabilities. At the southern range edge, higher growth may render individuals more susceptible to mortality where greater aboveground biomass results in greater water loss through evapotranspiration. [ABSTRACT FROM PUBLISHER]

Forest management practices in European temperate and Mediterranean regions have frequently exploited coppicing and pollarding – two silvicultural techniques that promote vegetative regeneration. These practices were historically very common with trees being cut at ground level or above the level of browsing to produce shoots, which were harvested for a variety of uses. Many habitats created from such traditional management are now recognized as areas of high conservation value, being rich in biodiversity. Yet their persistence has been under threat after these practices suffered a decline in the nineteenth century. The focus of this review is to synthesize information on coppicing and pollarding from the ecosystem to the molecular level and to highlight characteristics that may help or hinder climate adaptation. Understanding the benefits and hazards of exploiting vegetative regeneration is the first step in assessing whether promoting this means of reproduction could be exploited for conservation by increasing forest persistence in unfavourable future climate conditions. Practical management recommendations are given and suggestions are made for future research. [ABSTRACT FROM PUBLISHER]