Concepts of stress and limitation

Possibly the most widely used term in ecology, stress (a special, extreme form of limitation), is often used in a very misleading way. Note:


1 - Moving plants from the snowline to montane life conditions will be fatal for these plants. Most plants adapted to life at extreme high elevation do not survive in lowland botanical gardens, because the warmth exerts 'stress' and because they will be overgrown (outcompeted) by local species (Sajama volcano, Bolivia, 6542 m).
Ranunculus alpinus
2 - Fit to survive and reproduce under demanding environmental conditions (Ranunculus glacialis, Alps, 3150 m).

This picture was taken in the middle of the short nival zone summer (8 August). What looks fatal from a lowland perspective is not really problematic for high altitude specialists. These plants need only a few days of good weather in a 5 - 6 week summer to complete their seasonal life cycle. As perennials they can also survive years in which snow cover does not disappear. Surprisingly, these plants can even cope with substantial losses of green leaves due to snow-vole grazing, which suggests that they are not constrained by a shortage of photoassimilates.

2 - An example for the European Alps: Ranunculus glacialis in midsummer at 3150 m rapidly dies once transplanted to low elevation.