Alpine Ecosystems and Global Change

'Global change' includes changes in atmospheric chemistry (CO2, CH4, NjOj), the climatic consequences of these changes, and the manifold direct influences of humans on landscapes. All three global change complexes affect alpine biota, either directly or indirectly.

Elevated atmospheric carbondioxide (CO2) concentrations affect plant photosynthesis directly, although late-successional alpine grassland in the Alps was found to be carbon saturated at ambient CO2 concentrations of the early 1990s. The effect of doubling CO2 concentrations

Cushion Plants Kilimandscharo

Figure 5 The four major life-forms of flowering plants in alpine ecosystems: cushion plants (Azorella compacta, Sileneexscapa), herbs (small: Chrysanthemum alpinum, tall: Gentiana puncata), dwarf shrubs (Loiseleuria procumbens, Salix herbacea), and tussock-forming graminoids (Carex curvula, diverse tall grass tussock).

Figure 5 The four major life-forms of flowering plants in alpine ecosystems: cushion plants (Azorella compacta, Sileneexscapa), herbs (small: Chrysanthemum alpinum, tall: Gentiana puncata), dwarf shrubs (Loiseleuria procumbens, Salix herbacea), and tussock-forming graminoids (Carex curvula, diverse tall grass tussock).

over four consecutive seasons on net productivity was zero. However, not all species within that sedge-grass-herb community responded identically, hence there is a possibility of gradual shifts in species compositition in the long run, with some species getting suppressed and others gaining.

In contrast, even very moderate additions of soluble nitrogen fertilizer at rates of those received today by mountain forelands in Central Europe with rains (40— 50kgNha~ a~ ) doubled biomass in only 2 years. Even 25 kgha_1a_1 had immediate effects on biomass (+27%), again favoring some species more than others. Atmospheric nitrogen deposition is thus far more important for alpine ecosystems than elevated CO2. Just for comparison, in intense agriculture, cereals are fertilized with >200 kgNha-1 a~\

Consequences of climatic change for alpine ecosystems are hard to predict because of the interplay of climatic warming with precipitation. A warmer atmosphere can carry more moisture; hence increasing precipitation had been predicted for temperate mountain areas. Greater snowpack can shorten the growing season at otherwise higher temperatures. While the temperate zone has seen more late winter snow in recent years, the uppermost reaches ofhigher plants seem to have profited from climatic warming over the twentieth century. Several authors documented a clear enrichment of summit floras, accelerated in recent decades.

Treeline trees respond to warmer climates by faster growth, but whether and how fast this would cause the treelines of the world to advance upward depends on tree establishment, which is a slow process. Hence treelines always lagged behind climatic warming during the Holocene by centuries, as evidenced by pollen records. Current trends are largely showing an infilling of gaps in the treeline ecotone, but upward trends await larger-scale confirmation. Eventually any persistent warming will induce upward migration of all biota. By contrast, recent climatic warming has caused the tropical upper montane/ alpine climate on Kilimanjaro to become drier, facilitating devastating fires, which depressed the montane forest by several hundred meters with a downslope advance (expansion) of alpine vegetation following.

Land use is still the most important factor for changes in alpine ecosystems. Around the globe, alpine vegetation is used for herding or uncontrolled grazing by lifestock. Much of the treeline ecotone has been converted into pasture land, with both overutilization and erosion (mainly in developing countries) and abandonment of many centuries old, high-elevation cultural landscapes (mainly industrialized countries) causing problems. The question is not whether there should be pasturing, but how it should be done. Sustainable grazing requires shepherding and observation oftraditional practices, which largely prevent soil damage and erosion.

Traditional alpine land use has a several thousand years history and was optimized for maintaining an intact landscape for future generations as opposed to land-hungry newcomers faced with the need of feeding a family today, rather than thinking of sustained livelihood in a given area. All other forms of land use (except mining), as dramatic their negative effects at certain places may look, are less important, because their impact is rather local (e.g., tourism, road projects). Agriculture is by far the most significant factor in terms of affected land area.

Mismanagement of alpine ecosystems has severe consequences (e.g., soil destruction, sediment loading of rivers) not only for the local population, but for people living in large mountain forelands, which depend on steady supplies of clean water from high-altitude catchments. Almost 50% of mankind consumes mountain resources, largely water and hydrolectric energy, hence there is an often overlooked teleconnection between alpine ecosystems and highly populated lowlands. Highland poverty is thus affecting the conditions and the economic value of catchments, which goes far beyond the actual agricultural benefits. This insight should lead to better linkages between lowland and highland communities and also include economic benefit sharing with those that perform sustainable land care in alpine ecosystem.

See also: Alpine Forest; Land-Use Modeling. Further Reading

Akhalkatsi M and Wagner J (1996) Reproductive phenology and seed development of Gentianella caucasea in different habitats in the Central Caucasus. Flora 191: 161-168. Bahn M and Korner C (2003) Recent increases in summit flora caused by warming in the Alps. In: Nagy L, Grabherr G, Körner C, and Thompson DBA (eds.) Ecological Studies 167: Alpine Biodiversity in Europe, pp. 437-441. Berlin: Springer. Barthlott W, Lauer W, and Placke A (1996) Global distribution of species diversity in vascular plants: Towards a world map of phytodiversity. Erdkunde 50: 317-327. Billings WD (1988) Alpine vegetation. In: Barbour MG and Billings WD (eds.) North American Terrestrial Vegetation, pp. 392-420. Cambridge: Cambridge University Press. Billings WD and Mooney HA (1968) The ecology of arctic and alpine plants. Biological Reviews 43: 481-529. Bowman WD and Seastedt TR (eds.) (2001) Structure and Function of an Alpine Ecosystem - Niwot Ridge, Colorado. Oxford: Oxford University Press.

Callaway RM, Brooker RW, Choler P, et al. (2002) Positive interactions among alpine plants increase with stress. Nature 417: 844-848. Chapin FSIII and Körner C (eds.) (1995) Arctic and Alpine Biodiversity: Patterns, Causes and Ecosystem Consequences. Ecological Studies 113. Berlin: Springer. Dahl E (1951) On the relation between summer temperature and the distribution of alpine vascular plants in the lowlands of Fennoscandia. Oikos 3: 22-52.

Fabbro T and Korner C (2004) Altitudinal differences in flower traits and reproductive allocation. Flora 199: 70-81.

Grabherr G and Pauli MGH (1994) Climate effects on mountain plants. Nature 369: 448.

Hemp A (2005) Climate change-driven forest fires marginalize the impact of ice cap wasting on Kilimanjaro. Global Change Biology 11: 1013-1023.

Hiltbrunner E and Korner C (2004) Sheep grazing in the high alpine under global change. In: LUscher A, Jeangros B, Kessler W, etal. (eds.) Land Use Systems in Grassland Dominated Regions, pp. 305-307. Zurich: VDF.

Kalin Arroyo MT, Primack R, and Armesto J (1982) Community studies in pollination ecology in the high temperate Andes of central Chile. Part I: Pollination mechanisms and altitudinal variation. American Journal of Botany 69: 82-97.

Korner C and Larcher W (1988) Plant life in cold climates. In: Long SF and Woodward FI (eds.) Symposium of the Society of Experimental Biology 42: Plants and Temperature, pp. 25-57. Cambridge: The Company of Biology Ltd.

Korner C (2003) Alpine Plant Life, 2nd edn. Berlin: Springer.

Korner C (2004) Mountain biodiversity, its causes and function. AMBIO 13: 11-17.

Korner C (2006) Significance of temperature in plant life. In: Morison JIL and Morecroft MD (eds.) Plant Growth and Climate Change, pp. 48-69. Oxford: Blackwell.

Korner C and Paulsen J (2004) A world-wide study of high altitude treeline temperatures. Journal of Biogeography 31: 713-732.

Mark AF, Dickinson KJM, and Hofstede RGM (2000) Alpine vegetation, plant distribution, life forms, and environments in a perhumid New

Zealand region: Oceanic and tropical high mountain affinities. Arctic Antarctic and Alpine Research 32: 240-254.

Messerli B and Ives JD (eds.) (1997) Mountains of the World: A Global Priority. New York: Parthenon.

Meyer E and Thaler K (1995) Animal diversity at high altitudes in the Austrian Central Alps. In: Chapin FS, III, and Körner C (eds.) Ecological Studies 113: Arctic and Alpine Biodiversity: Patterns, Causes and Ecosystem Consequences, pp. 97-108. Berlin: Springer.

Miehe G (1989) Vegetation patterns on Mount Everest as influenced by monsoon and föhn. Vegetatio 79: 21-32.

Nagy L, Grabherr G, Korner C, and Thompson DBA (2003) Ecological Studies 167: Alpine Biodiversity in Europe. Berlin: Springer.

Pluess AR and Stocklin J (2004) Population genetic diversity of the clonal plant Geum reptans (Rosaceae) in the Swiss Alps. American Journal of Botany 91: 2013-2021.

Rahbek C (1995) The elevational gradient of species richness: A uniform pattern? Ecography 18: 200-205.

Sakai A and Larcher W (1987) Ecological Studies 62: Frost Survival of Plants. Responses and Adaptation to Freezing Stress. Berlin: Springer.

Spehn EM, Liberman M, and Korner C (2006) Land Use Change and Mountain Biodiversity. Boca Raton, FL: CRC Press.

Till-Bottraud J and Gaudeul M (2002) Intraspecific genetic diversity in alpine plants. In: Korner C and Spehn E (eds.) Mountain Biodiversity: A Global Assessment, pp. 23-34. New York: Parthenon.

Yoshida T (2006) Geobotany of the Himalaya. Tokyo: The Society of Himalayan Botany.

Was this article helpful?

0 0
Project Earth Conservation

Project Earth Conservation

Get All The Support And Guidance You Need To Be A Success At Helping Save The Earth. This Book Is One Of The Most Valuable Resources In The World When It Comes To How To Recycle to Create a Better Future for Our Children.

Get My Free Ebook


Post a comment