The Botanical Review

, Volume 75, Issue 2, pp 163–190 | Cite as

The Altitude of Alpine Treeline: A Bellwether of Climate Change Effects

  • William K. Smith
  • Matthew J. Germino
  • Daniel M. Johnson
  • Keith Reinhardt
Article

Abstract

Because of the characteristically low temperatures and ambient CO2 concentrations associated with greater altitudes, mountain forests may be particularly sensitive to global warming and increased atmospheric CO2. Moreover, the upper treeline is probably the most stressful location within these forests, possibly providing an early bellwether of forest response. Most treeline studies of the past century, as well as recently, have correlated temperatures with the altitudinal limits observed for treelines. In contrast, investigations on pre-establishment seedlings, the most vulnerable life stage of most tree species, are rare. There appears to be specific microclimatic factors dictated by wind and sky exposure that limit seedling survival, and also generate the distorted tree forms commonly observed at treeline. Seedling survival appears critical for creating the biological facilitation of microclimate at the community level which is necessary for the growth of seedlings to normal tree stature, forming new subalpine forest at a higher altitude.

Keywords

Treeline Timberline Ecotone Seedling Facilitation Climate 

Abstract

Es posible que—a causa de características que están asociadas con altitudes más altas: las bajas temperaturas y las concentraciones ambientales de dióxido de carbono—los bosques en las montañas están extra sensibles al calentamiento global y el aumento de dióxido de carbono en la atmósfera. El borde superior del bosque es probablemente el lugar con la más estrés y proviene uno de los primeros avisos de cómo reaccionará el bosque entero. En el pasado y hoy en día, la mayoría de los estudios del borde del bosque ha conectado la temperatura con los límites de la altitud. En contraste, investigaciones de árboles infantiles son raras, y la infancia de los árboles es el período de vida más vulnerable. Aparece que hay factores micro-climáticos dictados por la exposición del viento y cielo que limitan la sobrevivencia de los árboles infantiles, y que generan árboles deformados observados al borde del bosque. Es más, la sobrevivencia de árboles infantiles es crítica para crear la facilitación biológica del micro-clima en una comunidad arbolada. Esta facilitación es necesaria para el crecimiento de árboles infantiles a árboles maduros, los que forman un nuevo bosque subalpino en una altitud más alta.

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Copyright information

© The New York Botanical Garden 2009

Authors and Affiliations

  • William K. Smith
    • 1
  • Matthew J. Germino
    • 2
  • Daniel M. Johnson
    • 3
  • Keith Reinhardt
    • 1
  1. 1.Department of BiologyWake Forest UniversityWinston-SalemUSA
  2. 2.Idaho State University, Biological SciencesPocatelloUSA
  3. 3.USDA Forest Service, Forestry Sciences LaboratoryCorvallisUSA

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