Impacts of predicted climate change on recruitment at the geographical limits of Scots pine.

Luis Matías,Alistair S Jump

doi:10.1093/jxb/ert376

Abstract

Ongoing 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.

Highlights

Plant distributions are strongly determined by climate (Houle, 1994; Walck et al, 2011)
In order to test the possible effect of climate alterations on the recruitment pattern at the species’ range limits, we designed an experiment with three main factors: (i) seed provenance: with two levels (Table 1), northern and southern; (ii) temperature: with four different levels (Table 2), current main temperature during growing season at the northern limit of the species, predicted temperature by 5 °C at the northern limit for the end of the present century, current main temperature during growing season at the southern limit of the species, and predicted temperature by 5 °C at the southern limit for the end of the present century
Southern temperatures enhanced emergence proportion compared with northern ones, the temperature increase expected for the coming decades within each range limit had no effect, as north future (NF) and south future (SF) treatments were comparable to north current (NC) and south current (SC) treatments, respectively

Summary

Introduction

Plant distributions are strongly determined by climate (Houle, 1994; Walck et al, 2011). Temperature and precipitation are critical drivers for plant distribution at the global scale (Woodward, 1987) because they strongly influence seed germination, growth, and survival at the population scale (Arft et al, 1999; Diemer, 2002; Walck et al, 2011). The geographical limits of species distributions are generally considered more susceptible to changes in climate as ecological conditions there are often already at the limit of the species’ tolerance (Hampe and Petit, 2005). This ecological marginality can result in lower relative fecundity and lower local population densities (Case and Taper, 2000), which could result in reduced resilience under adverse climate conditions.

Objectives

Methods

Results

Conclusion