Frost avoidance and freezing tolerance in Afroalpine ‘giant rosette’ plants

Beck, Erwin; Senser, Margot; Scheibe, Renate; Steiger, Hans-Martin; Pongratz, Paul

doi:10.1111/1365-3040.ep11572080

Cited by 29 publications

(22 citation statements)

References 13 publications

(2 reference statements)

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“…For example, the LT 50 of leaves of the alpine plants from the Venezuelan Andes (8°37¢N, 70°12¢W) ranged between À8°C and À19°C (median À12°C) (Squeo et al 1991), whereas that of alpine plants growing at 3,200 m in the northern Chilean Andes (29°45¢S, 69°59¢W) ranged from À4.7°C to À20°C (median À13.3°C) (Squeo et al 1996). The Hawaiian alpine mega-herb, Agyroxiphium sandwicense (silversword), had a frost resistance of À15°C (Goldstein et al 1996) while the Afro-alpine mega-herbs Senecio keniodendron and S. keniensis had frost resistances of À14°C and À10°C respectively, and the giant lobelias (L. telekii and L. keniensis) resisted temperatures as low as À20°C (Beck et al 1982). Other herbaceous Afro-alpine species had frost tolerance between À13°C and À15°C (median À14°C) (Beck 1994).…”

Section: Comparisons With Plants From Other Alpine Areasmentioning

confidence: 99%

Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?

et al. 2005

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If snow cover in alpine environments were reduced through climatic warming, plants that are normally protected by snow-lie in winter would become exposed to greater extremes of temperature and solar radiation. We examined the annual course of frost resistance of species of native alpine plants from southern New Zealand that are normally buried in snowbanks over winter (Celmisia haastii and Celmisia prorepens) or in sheltered areas that may accumulate snow (Hebe odora) and other species, typical of more exposed areas, that are relatively snow-free (Celmisia viscosa, Poa colensoi, Dracophyllum muscoides). The frost resistance of these principal species was in accord with habitat: those from snowbanks or sheltered areas showed the least frost resistance, whereas species from exposed areas had greater frost resistance throughout the year. P. colensoi had the greatest frost resistance (-32.5 degrees C). All the principal species showed a rapid increase in frost resistance from summer to early winter (February-June) and maximum frost resistance in winter (July-August). The loss of resistance in late winter to early summer (August-December) was most rapid in P. colensoi and D. muscoides. Seasonal frost resistance of the principal species was more strongly related to daylength than to temperature, although all species except C. viscosa were significantly related to temperature when the influence of daylength was accounted for. Measurements of chlorophyll fluorescence indicated that photosynthetic efficiency of the principal species declined with increasing daylength. Levels of frost resistance of the six principal alpine plant species, and others measured during the growing season, were similar to those measured in tropical alpine areas and somewhat more resistant than those recorded in alpine areas of Europe. The potential for frost damage was greatest in spring. The current relationship of frost resistance with daylength is sufficient to prevent damage at any time of year. While warmer temperatures might lower frost resistance, they would also reduce the incidence of frosts, and the incidence of frost damage is unlikely to be altered. The relationship of frost resistance with daylength and temperature potentially provides a means of predicting the responses of alpine plants in response to global warming.

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Section: Comparisons With Plants From Other Alpine Areasmentioning

confidence: 99%

Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?

et al. 2005

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“…Continuous 24-h measurements of leaf and leaf bud temperatures of giant rosettes in comparison with the air temperatures were reported by Smith (1974) and Beck et al (1982). Smith (1980) also described the gradient in air temperature from ground level up to 2.0 m in height.…”

Section: Introductionmentioning

confidence: 83%

“…Caulescent individuals of L. rhynchopetalum have broad and glabrous leaves while those of acaulescent individuals are narrow and more pubescent. It has been suggested that in tropical alpine plants, leaf pubescence serves to decrease early morning transpiration by increasing boundary layer resistance (Beck et al 1982;. Thus, leaf pubescence in acaulescent lobelias may be an adaptation to reduce water loss by transpiration or evaporation from frozen leaves in the early morning.…”

Section: Discussionmentioning

confidence: 99%

“…Plant responses to the diurnal temperature¯uctuations in the tropical alpine zone have been the subject of many investigations (Hedberg 1964;Smith 1974Smith , 1980Beck et al 1982;Miller 1986). Continuous 24-h measurements of leaf and leaf bud temperatures of giant rosettes in comparison with the air temperatures were reported by Smith (1974) and Beck et al (1982).…”

Section: Introductionmentioning

confidence: 99%

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Microclimate and ecophysiological significance of the tree-like life-form of Lobelia rhynchopetalum in a tropical alpine environment

Fetene

Gashaw²,

Nauke

et al. 1998

Oecologia

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The microclimate and the adaptive significance of the tree-like plant life-form for growth in a tropical alpine environment was investigated with the pachycaul arborescent giant rosette plant, Lobelia rhynchopetalum (Hochst. A. Rich.) Hemsl. in the Bale and Simen Mountains, Ethiopia. The microclimate of plants of three height classes was examined with respect to temperature, relative humidity and the effect of wind. Although the total heat gains were rather similar, leaves of young, still stemless (acaulescent) individuals of Lobelia were subjected to a high diurnal temperature fluctuation of up to 29 K compared to a 14-K fluctuation for the leaves of an individual 3.5 m in height. During the cold nights, temperatures of the inner rosette leaves and inside leaf buds of caulescent plants were 4-5 K above air temperature, while corresponding temperatures of acaulescent individuals were 1-2 K below air temperature. The inner temperature of the stem tissue was higher than the surface temperature of the stem by about 5 K for most of the cold night. The annual rates of increment in whole plant, stem and rosette height, and stem diameter of L. rhynchopetalum showed that the young, still acaulescent individuals, with an annual increment of 5.6 cm in plant height, had the lowest growth rate, compared to 12.1 and 22.1 cm for caulescent life-forms. The results show that the most important advantage gained by the tree-like life-form of adult L. rhynchopetalum is probably a more favourable microclimate in which the strong diurnal temperature fluctuations at the ground are mitigated and nocturnal temperatures do not drop below freezing point.

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“…Furthermore, low temperatures in combination with high light intensities which we frequently measured in the open but not under the shelter of Helichrysum shrubs are commonly known to induce low-temperature photoinhibition of photosynthetic processes caused by negative effects on plant enzymatic processes (Germino and Smith 2000; Johnson et al 2004). Various growth forms such as, for example, giant rosette plants have been shown to be physiologically adapted to these kinds of stressors (Beck et al 1982;Goldstein et al 1989). However, photoinhibition which is assumed to be a common stressor in tropical alpine regions (Fetene et al 1997) could harm other species such as A. jonstonii which are not sheltered against the harsh environmental conditions.…”

Section: Discussionmentioning

confidence: 99%

The Afro-alpine dwarf shrubHelichrysum citrispinumfavours understorey plants through microclimate amelioration

Schweiger¹,

Otieno

Kulunge

et al. 2015

Plant Ecology & Diversity

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Background: Positive plant-plant interactions similar to specialised plant growth forms are potential strategies to overcome the environmental harshness of Afro-alpine ecosystems. However, knowledge about plant-plant interactions is limited for African alpine regions. Aims: We investigated the ameliorative effect of the densely leaved dwarf shrub Helichrysum citrispinum on two frequently co-occurring herbaceous plant species in the alpine zone of Mt. Kilimanjaro. Methods: We recorded microclimatic conditions, plant water potentials and gross primary production (GPP) for plants of the low-growing perennial Alchemilla johnstonii and the tussock grass Festuca abyssinica and compared these parameters between open sites and under H. citrispinum shrubs between July and August 2012. Results: Shrubs significantly buffered daily variation and extreme values of irradiation, air-, plant surface-and soiltemperatures as well as vapour pressure deficit. We found enhanced plant water potentials and gross primary production for shaded plants of both species investigated; ameliorative effects were higher for A. johnstonii than for F. abyssinica. Conclusions: Habitat amelioration of H. citrispinum significantly improves the productivity of plant species that grow under the shrub, although the net outcome may be affected by interspecific growth form differences. Future studies on positive plant-plant interactions should more strongly focus on the ecophysiological consequences of habitat amelioration.

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Frost avoidance and freezing tolerance in Afroalpine ‘giant rosette’ plants

Cited by 29 publications

References 13 publications

Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?

Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?

Microclimate and ecophysiological significance of the tree-like life-form of Lobelia rhynchopetalum in a tropical alpine environment

The Afro-alpine dwarf shrubHelichrysum citrispinumfavours understorey plants through microclimate amelioration

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