Leaf and floral heating in cold climates: do sub-Antarctic megaherbs resemble tropical alpine giants?

  • Lorna Little University of Otago, New Zealand University Centre in Svalbard, Norway
  • Pernille Bronken Eidesen Arctic Biology at theUniversity Centre in Svalbard
  • Eike Müller Arctic Biology at the University Centre of Svalbard
  • Katharine J.M. Dickinson University of Otago
  • Janice M. Lord University of Otago
Keywords: Campbell Island, flower colour, thermal imaging, Pleurophyllum speciosum

Abstract

High latitude and altitude floras are characterized by low-statured, small, wind-pollinated plants, which mainly reproduce by self-pollination or asexual reproduction. However, at odds with this are some sub-Antarctic islands that have plant species with giant growth forms and large, brightly coloured flowers which require insect visitation for pollination. The size, colour and shape of the inflorescences and leaves of these megaherbs suggest thermal benefits similar to giant tropical alpine plants of equatorial Africa, South America and Hawaii. We evaluated whether heating occurs in sub-Antarctic megaherbs, and to what extent it is related to environmental variables. We measured leaf and inflorescence temperature in six sub-Antarctic megaherb species on Campbell Island, latitude 52.3°S, New Zealand Biological Region. Using thermal imaging techniques, in combination with measurement of solar radiation, ambient air temperature, wind speed, wind chill and humidity, we assessed environmental influences on leaf and floral heating. We found that leaf and inflorescence temperatures of all megaherbs were higher than simultaneously measured ambient temperatures. Greatest heating was seen in Pleurophyllum speciosum, with observed leaves 9°C higher, and inflorescences nearly 11°C higher, than ambient temperature. Heating was highly correlated with brief, unpredictable periods of solar radiation, and occurred most rapidly in species with hairy, corrugated leaves and darkly pigmented, densely packed inflorescences. This is the first evidence that floral and leaf heating occurs in sub-Antarctic megaherbs, and suggests that leaf hairiness, flower colour and shape could provide thermal benefits like those seen in tropical alpine megaherbs.

Keywords: Campbell Island; flower colour; thermal imaging; Pleurophyllum speciosum.

(Published: 29 August 2016)

To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools).

Citation: Polar Research 2016, 35, 26030, http://dx.doi.org/10.3402/polar.v35.26030

Downloads

Download data is not yet available.

Author Biographies

Lorna Little, University of Otago, New Zealand University Centre in Svalbard, Norway

PhD Student at Department of Botany at the University of Otago and Arctic Biology at the Unversity Centre in Svalbard

Pernille Bronken Eidesen, Arctic Biology at theUniversity Centre in Svalbard

Associate Professor

Arctic Biology

Eike Müller, Arctic Biology at the University Centre of Svalbard

Dr

Arctic Biology

Katharine J.M. Dickinson, University of Otago

Professor

Department of Botany

Janice M. Lord, University of Otago

Senior Lecturer

Department of Botany

Published
2016-08-29
How to Cite
Little, L., Eidesen, P., Müller, E., Dickinson, K., & Lord, J. (2016). Leaf and floral heating in cold climates: do sub-Antarctic megaherbs resemble tropical alpine giants?. Polar Research, 35. https://doi.org/10.3402/polar.v35.26030
Section
Research/review articles