Gardening in the zone of death: an experimental assessment of the absolute elevation limit of vascular plants.

Miroslav Dvorský,Jiří Doležal,Kateřina Čapková,Martin Macek,Zuzana Chlumská,Klára Řeháková,Martin Kopecký,Jan Altman,Pierre Liancourt

doi:10.1038/srep24440

Abstract

Vascular plants in the western Tibetan Plateau reach 6000 m-the highest elevation on Earth. Due to the significant warming of the region, plant ranges are expected to shift upwards. However, factors governing maximum elevational limits of plant are unclear. To experimentally assess these factors, we transplanted 12 species from 5750 m to 5900 m (upper edge of vegetation) and 6100 m (beyond range) and monitored their survival for six years. In the first three years (2009–2012), there were plants surviving beyond the regional upper limit of vegetation. This supports the hypothesis of dispersal and/or recruitment limitation. Substantial warming, recorded in-situ during this period, very likely facilitated the survival. The survival was ecologically a non-random process, species better adapted to repeated soil freezing and thawing survived significantly better. No species have survived at 6100 m since 2013, probably due to the extreme snowfall in 2013. In conclusion, apart from the minimum heat requirements, our results show that episodic climatic events are decisive determinants of upper elevational limits of vascular plants.

Highlights

Frost-heave and solifluction in dry substrates), (3) suitable geology such as metamorphic bedrock producing relatively fine substrates at a limited occurrence of coarse screes, and (4) location within a subtropical belt
The increasing trend of summer and winter precipitation over the Himalaya is associated with an increasing trend in precipitation extremes connected to the changing pattern of the summer monsoons[20,24,25,26,27], and an enhancement in the strength and frequency of winter westerly disturbances[18,28,29,30,31], respectively
This supports the hypothesis of dispersal and/or recruitment limitation

Summary

Introduction

Frost-heave and solifluction in dry substrates), (3) suitable geology such as metamorphic bedrock producing relatively fine substrates at a limited occurrence of coarse screes, and (4) location within a subtropical belt (high solar input) All of these conditions predominate over the whole south and west Tibetan Plateau (which stretches to East Ladakh), where even higher limits of continuous vegetation can be expected. As the effect of increased precipitation on the direction of the vegetation shift may be opposite to the effect of warming, the principal questions are whether the current upper species ranges are (1) in an equilibrium state with the current climate, (2) lagging behind the climate amelioration (warming) due to dispersal limitations, i.e. there are uninhabited habitats available beyond the current range, or (3) paying the extinction debt (mortality time lag) because of the deterioration of conditions (prevailing adverse effect of higher water input or more extreme variability of cold and warm conditions). Fertilization was included in the experiment to examine possible effects of nutrient limitation

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Discussion

Conclusion