Stomatal response functions to environmental stress of dominant species in the tropical Andean páramo

ABSTRACT

Background: Stomatal response functions of dominant plant species can provide insights into the behaviour of ecosystems under environmental stress, and provide tools for modelling their response to climate change. However, they remain little studied in tropical Alpine ecosystems.

Aims: Our objective was to formulate and compare stomatal response functions for two dominant páramo species with different adaptive strategies to drought, the stress-tolerant shrub Hypericum laricifolium, and the stress avoiding giant rosette Espeletia schultzii and thus enable making projections as to their future fitness in a changing climate.

Methods: A reanalysis of data found in the literature and new ecophysiological and micrometeorological measurements were used to fit and test new stomatal response functions to environmental variables for these two species.

Results: The response functions of vapour pressure differences between leaf and air showed an exponential decrease for both species, while for photosynthetically active radiation (PAR), peak-form response functions provided the best fit. The response function for leaf water potential was linear for the drought-tolerant shrub and decreased exponentially for the stress avoiding giant rosette. Several thresholds prior to stomatal closure were also included in the functions.

Conclusions: Although stress-avoiding and stress-tolerant strategies are both successful in the Andean páramo, the response functions suggest that the tolerant shrub could be more resistant to more intense drought.

KEYWORDS:

• Ecophysiology
• Espeletia
• frailejon
• giant rosettes
• Hypericum
• shrubs
• stomatal conductance
• transpiration
• tropical alpine
• water stress

Acknowledgements

The authors thank Mayanin Rodriguez and Dimas Acevedo for providing the meteorological data, William Dugarte for his logistic support; Luis D. Llambi, Laszlo Nagy and three anonymous reviewers for their valuable comments and suggestions that greatly improved the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

David Sandoval

David Sandoval is developing his Ph.D. thesis on climate change effects on carbon and water fluxes in mountain ecosystems. His research interests comprise ecohydrology, ecophysiology and land surface modelling.

Fermín Rada

Fermin Rada is a professor who specialises in plant physiological ecology, focusing on plant responses to different stresses, mainly related to temperature and water, in diverse tropical ecosystems.

Lina Sarmiento

Lina Sarmiento is a professor whose research is focused on soil restoration, vegetation dynamics during secondary successions and agroecology of Andean crops, with emphasis on water balance and nitrogen cycling.