Birch as a Model Species for the Acclimation and Adaptation of Northern Forest Ecosystem to Changing Environment

Abstract

Northern forest ecosystems are exposed to rapid climate change, i.e., climate warming, extended growing seasons, increasing greenhouse gases, and changes in precipitation and water availability, accompanied by increasing pressure of herbivores and pathogens. Silver birch (Betula pendula Roth) is an important deciduous trees species in the boreal zone, with extensive distribution across Eurasia. Silver birch is an excellent model system for the adaptation of northern trees to climate change due to recent advances in genomics, high genetic variation, and intensive studies with different abiotic and biotic stress factors. In this paper, the current understanding about the responses and acclimation mechanisms of birch to changing environment is presented, based on Fennoscandian studies. Several complementary experiments in laboratory, semi-field and natural field conditions have shown that warming climate and increasing CO2 is expected to increase the growth and biomass of birch, but the risk of herbivore damage will increase with negative impact on carbon sink strength. Deleterious impacts of high humidity, soil drought and increasing ozone has been clearly demonstrated. All these environmental changes have led to metabolic shifts or changes in carbon/nutrient balance which may have further ecological impacts. However, high plasticity and genotypic variation predict excellent acclimation capacity in rapidly changing environment and a rich genetic pool for sustainable forestry. Because the trees and forest ecosystems are exposed to multiple environmental factors simultaneously, it is necessary to continue research with multiple-stress interaction studies.