This is Section 14.1 of the Arctic Climate Impact Assessment.

Lead Author: Glenn P. Juday;  Contributing Authors: Valerie Barber, Paul Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, Eugene Vaganov, John Yarie; Consulting Authors: Edward Berg, Rosanne D’Arrigo, Olafur Eggertsson,V.V. Furyaev, Edward H. Hogg, Satu Huttunen, Gordon Jacoby,V.Ya. Kaplunov, Seppo Kellomaki, A.V. Kirdyanov, Carol E. Lewis, Sune Linder, M.M. Naurzbaev, F.I. Pleshikov, Ulf T. Runesson,Yu.V. Savva, O.V. Sidorova,V.D. Stakanov, N.M.Tchebakova, E.N.Valendik, E.F.Vedrova, Martin Wilmking.

The Arctic has been defined in somewhat different ways in various studies, reports, and assessments, based primarily on the purpose of the project. While the most restrictive definitions limit the Arctic to treeless tundra, snow, and ice in the high latitudes, most definitions of the Arctic encompass some elements of the boreal forest. The definition used by the Arctic Monitoring and Assessment Programme^[1] (see section 8.1.1, Fig. 8.2), for example, includes the productive boreal forests of northwest Canada and Alaska, but includes mostly marginal treeline forest and woodland in eastern Canada. Permafrost-free forests in the northern portion of the Nordic countries are within the AMAP-defined Arctic, but across central and eastern Siberia, the boundary follows the margin of sparse northern taiga and forest–tundra. This chapter focuses on the northernmost portion of the boreal forest region, but broadens consideration of the subject for two important reasons. First, many elements of the boreal forest are best understood as a whole (e.g., the gradients of changing tree responses to the environment from south to north), and this chapter includes an extensive and well studied Siberian transect that uses such an approach. Second, the five scenarios of climate change generated by the ACIA-designated models (section 4.4) project temperatures within the Arctic that today only occur in the boreal forest far to the south. If temperature increases of a magnitude similar to those projected by these models actually occur, the nearest analogues of climate (and eventually ecosystems) that would exist in the Arctic are those of more southerly boreal forest regions.

Sections 14.2 and 14.3 describe forest characteristics across the northern boreal forest to provide the context for understanding the importance of recent climate-related changes in the region and potential future change. Section 14.4 provides an overview of the climate scenarios generated by the ACIA-designated models and describes how the scenarios were used in different aspects of the assessment.

While many factors affect agriculture in the far north (e.g., changing markets, social trends, and national and international policies), section 14.5 focuses on the climate-sensitive aspects of crop production systems that would be affected under the scenarios of future climate, focusing on climate stations representative of areas with agricultural production or potential. Section 14.3 also considers the challenges that climate change poses for land management. Tree rings are one of the most important sources of information about past climates, especially in the sparsely populated far north, and section 14.6 reviews the record of climate and tree rings across the Arctic and northern boreal region.

Section 14.7 presents new information about the direct effects of climate on tree growth in the northern boreal forest, in both the distant and more recent past, and uses scenarios generated by the ACIA-designated models to project how climate change may affect the growth of selected tree species during the 21st century. Section 14.8 identifies key climate controls on large-scale population increases in insects that damage trees, and provides some recent evidence of these effects.

Forest fire is another major indirect effect of climate on the status of forests in the far north. Section 14.9 examines some of the climate-sensitive aspects of fire and possible future fire conditions and effects. The climate-related changes in growth, insect-caused tree death or reductions in tree growth, and fire are major factors that control the uptake and storage of atmospheric carbon (section 14.10). The implications of future climate change for forest distribution are briefly considered in section 14.11. Finally, section 14.12 summarizes some recently published information on the effects of increased UV-B radiation levels on boreal forest species, and section 14.13 reviews critical research needs.

Chapter 14: Forests, Land Management, and Agriculture
14.1. Introduction
14.2. The boreal forest: importance and relationship to climate
14.3. Land tenure and management in the boreal region
14.4. Use and evaluation of the ACIA scenarios
14.5. Agriculture
14.6. Tree rings and past climate
14.7. Direct climate effects on tree growth
14.8. Climate change and insects as a forest disturbance
14.9. Climate change and fire
14.10. Climate change in relation to carbon uptake and carbon storage
14.11. Climate change and forest distribution
14.12. Effects of ultraviolet-B on forest vegetation
14.13. Critical research needs

References

1. ^ AMAP, 1997. Arctic Pollution Issues: A State of the Environment Report. Arctic Monitoring and Assessment Programme, Oslo, 188p.