Effect of Climate Change on the High-Mountain Tree Species and Their Genetic Resources in Bulgaria

Abstract

Climate change have the potential to strongly affect mountain coniferous forests in Bulgaria in several ways: (1) By directly affecting tree growth and the potential of trees to successfully cope with climate extremes; (2) By affecting disturbance events and regimes, which on their turn may trigger further habitat changes; (3) By facilitating migration of better adapted for the new climate condition species, which can outcompete other less adapted species and replace them and (4) By facilitating invasive species. In this chapter we provide data on the distribution of coniferous forests in Bulgarian mountains and short reviews of recent tree ring studies and studies on disturbance regimes. The tree ring data show the high importance of drought and other extreme climate events on high-mountain conifer species. This outlines that expected summer warming and temperature increase have the potential to strongly affect tree growth. The disturbance data shows the high importance of fires and windthrows, but also high number of snow damages and avalanches, which are not to be neglected. Insect outbreaks may be further facilitated if summer temperatures increase and allow species, which are currently limited by colder temperatures in higher altitudes, to affect also forests higher up. All these factors can act together and modify habitat quality and conditions and in this way put in risk species and genotypes with limited distribution and narrow growth niches. It is therefore necessary to take measures for ex-situ conservation of genotypes besides the well developed in-situ conservation in the network of protected areas in Bulgaria.