Conclusions

Not every deviation from optimal life conditions is stress. These deviations are essential for fitness. Only those which are not fit are stressed. Alpine plants are fit for their particular environment. This is the reason why they thrive in environments where others cannot and where humans feel stressed. Low temperature extremes can cause partial tissue damage in summer but are never fatal for plants. While freezing resistance varies across a wide range of temperatures among species, heat resistance thresholds are relatively similar across species. Very sensitive species may be damaged at 46 °C, the maximum resistance in higher plants is around 56 °C, with most plant species being damaged at around 50 °C (±2 K). Extremely high solar radiation can be problematic during snowmelt, but alpine plants are generally well protected by UV filtering substances.

Further reading

Part of this unit has been extracted from Körner Ch (2003) Alpine Plant Life: functional plant ecology of high mountain ecosystems. Springer, Berlin, chapter 8

Sakai A, Larcher W (1987) Frost survival of plants. Responses and adaptation to freezing stress. Ecol Stud, vol 62. Springer, Berlin

Acknowledgements

Christian Körner
(Institute of Botany, Ecology - University of Basel)
Concept and content, photographs
Thomas Zumbrunn
(Institute of Zoology, Evolution - University of Basel)
Technical realisation, photographs

Glossary

annoxia
Lack of oxygen
apoplast
The part of a plant tissue outside the outer protoplast membrane. Commonly the sum of cell walls (cellulose) and intercellular spaces.
diaspore
Reproductive propagule (a seed or a fruit) of a plant
hotspot
A center of attraction or richness (e.g. in species)
mole
The molecular weight expressed in the unit gram
phalanx
A massed arrangement of people, animals or plants. Greek for a closed progressing front of soldiers.
phenology
The visible change of developmental stages (e.g. sprouting, flowering, fruiting)
photoperiod
The duration of daylight
photoperiodism
The response of plants to the ratio of the length of the light/dark period
phototoxicity
Damage caused by high light intensity
protoplast
The naked cell (in plants, without the cell wall)
turgor
Cell pressure

References

Körner Ch (2003) Alpine Plant Life: functional plant ecology of high mountain ecosystems. Springer, Berlin (2nd edition)
Robberecht R, Caldwell MM, Billings WD (1980) Leaf ultraviolet optical properties along a latitudinal gradient in the arctic-alpine zone. Ecology 61:612-619
Sakai A, Larcher W (1987) Frost survival of plants. Responses and adaptation to freezing stress. Ecol Stud, vol 62. Springer, Berlin