This paper provides concise information on methods used in measuring the observed impact of ongoing climate change on the evolution of tree-species in the composition of forest stands. We include the structure and quality of forest ecosystem services provided. In describing possible future biological diversity changes, the assessment of assumed climate change impact on forest ecosystems is based on global circulation models and corresponding regional climate scenarios. The uncertainty of future climate development is expressed in the more pessimistic SRES A2 and more optimistic SRES B1 emission recommendations by the United Nations Inter-governmental Panel on Climate Change. The selected scenarios enabled prediction of CO2 levels in the atmosphere and changes in air humidity and soil environment. Herein, the Shannon Biodiversity Index was applied to evaluate assumed biodiversity changes in Low Tatra Mts. forest areas and results show the index increasing from the current 0.4 to 0.9 by 2075. Change in both the quantity and quality of provided forest ecosystem services is expected as a result of uncertainty in its tree-species composition, stock volume and the increasing specific risks in forest land management. Therefore a shift in the managerial paradigm from the present “safe forestry” to the future “risky forestry” is proposed to efficiently limit uncertainty and risks to forest management. Acceptance of this proposal will reduce forest vulnerability to future climate extremes.