Trees at their Upper Limit: treelife limitation at the alpine timberline.

Preface. Contributors. - 1. Current concepts for treelife limitation at the upper timberline. 1.1 Introduction. 1.2 Altitudinal position of the upper timberline and its relation to climate. 1.3 Current concepts of upper tree life limits. 1.3.1 Climatic stress. 1.3.2 Disturbance. 1.3.3 Insufficient carbon balance. 1.3. 4 Limitation to cell growth and tissue formation. 1.3. 5 Nutritional limitation. 1.3. 6 Limited regeneration. References. - 2. Climate at the upper timberline. 2.1 Introduction. 2.2 Effects of altitude. 2.3 Effects of topography. 2.4 Canopy and soil temperatures. References. - 3. Soils - heterogeneous at a microscale. 3.1 Introduction. 3.2 Specific pedogenetic factors at the timberline. 3.2.1 Parent material. 3.2.2 Precipitation. 3.2.3 Soil moisture. 3.2.4 Soil temperature. 3.2. 5 Erosion processes and soil age. 3.2. 6 Permafrost. 3.2. 7 Vegetation and soil. 3.2. 8 Timberline fluctuations. 3.2. 9 Grazing. 3.3 Soil types and humus forms. 3.3.1 Soils on siliceous parent material. 3.3.2 Soils on calcareous parent material. References. - 4. Mycorrhiza in the alpine timberline ecotone: nutritional implications. 4.1 Introduction. Mycorrhizal symbioses in the alpine-treeline ecotone. 4.3 Nutritional aspects with special reference to organic nitrogen. 4.4 Concluding remarks. References. - 5. Vegetation at the upper timberline. 5.1 Introduction. 5.2 Growth forms at the timberline. 5.3 Plant communities at the timberline. 5.3.1 Spruce forests (Picea abies communities). 5.3.2 Fir forests (Abies alba communities). 5.3.3 Larch-Swiss stone pine forests (Larix decidua-Pinus cembra communities). 5.3. 4 Larch forests (Larix decidua communities). 5.3. 5 Pinus uncinata forests. 5.3. 6 Prostrate pine scrub (Pinus mugo communities). 5.3. 7 Sycamore-beech forest (Acer pseudoplatanus-Fagus sylvatica communities). 5.3. 8 Green alder and willow scrub. 5.3. 9 Dwarf shrub heath. 5.3.10 Substitutional communities due to human landuse at the timberline. References. - 6. Limitation by an insufficient carbon assimilation and allocation. 6.1 Introduction. 6.2 Uptake and loss of carbon dioxide. 6.2.1 Net photosynthetic capacity and specific respiratory capacity of trees in the timberline ecotone. 6.2.2 Net photosynthetic capacity and specific respiratory activity with respect to altitude. 6.2.3 Environmental constraints of carbon dioxide gas exchange. 6.3 Carbon balance and allocation. 6.3.1 The carbon balance. 6.3.2 Carbon allocation. 6.4 Carbon accumulation of trees in the timberline ecotone. 6.4.1 Dry matter accumulation patterns. 6.4. 2 Changes in carbon accumulation with tree age. 6.5 Net ecosystem production at timberline. References. - 7. Limitation by growth processes. 7.1 Introduction. 7.2 Shoot growth at low temperatures. 7.3 Root growth at low soil temperature. 7.4 Threshold temperature for growth. References. - 8. Limits in water relations. 8.1 Introduction. 8.2 Precipitation, soil moisture and evaporation. 8.3 Transpiration. 8.4 Water Transport. 8.5 Water uptake. 8.6 Water balance. References. - 9. Phytopathogens at the alpine timberline. 9.1 Introduction. 9.2 Fungal pathogens at the alpine timberline. 9.3 Effects of the needle rust Chrysomyxa on Norway spruce. References. - 10. Frost resistance at the upper timberline. 10.1 Introduction. 10.2 Frost damage. 10.2.1 Winter. 10.2.2 Frost hardening capacity. 10.2.3 Summer. 10.2.4 Rate of temperature change. References. - 11. Photo-oxidative stress at the timberline. 11.1 Introduction. 11.2 Mechanisms of ROS production in green plant cells under stress. 11.3 Antioxidative and photoprotective systems in plant cells. 11.4 Factors causing photo-oxidative stress at the timberline. 11.5 Antioxidative and photoprotecti