Freezing tolerance in Draba chionophila, a ?miniature? caulescent rosette species

Azócar, Aura; Rada, Fermín; Goldstein, Guillermo

doi:10.1007/bf00378830

Cited by 36 publications

(28 citation statements)

References 14 publications

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“…Grasses in the páramo grow under more unfavorable ground level thermal conditions due to nocturnal surface heat loss (Azócar and Monasterio 1980;Azócar et al 1988;Earnshaw et al 1990;Squeo et al 1991), compared to the species of Espeletia (Goldstein et al 1985;Rada et al 1987) and Polylepis sericea (Rada et al 1985b), which grow well above ground. Under such environmental conditions, supercooling itself does not seem to be an eVective mechanism to resist night freezing temperatures.…”

Section: Discussionmentioning

confidence: 99%

“…In tropical environments, tolerance has been selected where night temperatures drop far below 0°C remaining there for several hours (Rada et al 1985b;Sakai and Larcher 1987). Freezing tolerance was Wrst reported for the tropical Andes in Draba chionophila (Brassicaceae), a small rosette which grows under extreme climatic conditions at 4,800 m, and sustains tissue freezing at ¡5°C and injury at ¡14°C (Azócar et al 1988). There seems to be a close relationship between plant height and life form: taller plants, including rosettes, display predominantly avoidance mechanisms, while smaller ones exhibit tolerance (Squeo et al 1991(Squeo et al , 1996.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, plant species are conditioned to sustain freezing resistance mechanisms all year round as an evolutive response to this environment (Sarmiento 1986). However, plants have diVerent ways of responding to low temperatures and partially depend on microclimatic environmental conditions around the plant (Azócar et al 1988), giving rise to avoidance or tolerance to extracellular freezing (Levitt 1972).…”

Section: Introductionmentioning

confidence: 99%

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Freezing tolerance in grasses along an altitudinal gradient in the Venezuelan Andes

2006

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The tropical high Andes experience greater daily temperature oscillations compared to seasonal ones as well as a high frequency of night frost occurrence year round. Survival of organisms, under such environmental conditions, has been determined by selective forces which have evolved into adaptations including avoidance or tolerance to freezing. These adaptations have been studied in diVerent species of trees, shrubs and perennial herbs in páramo ecosystems, while they have not been considered in grasses, an important family of the páramo. In order to understand survival of Poaceae, resistance mechanisms were determined. The study was performed along an altitudinal gradient (2,500-4,200 m a.s.l.) in the páramo. Supercooling capacity and frost injury temperature were determined in nine species in order to establish cold resistance mechanisms. Grasses registered a very low supercooling capacity along the altitudinal gradient, with ice formation between ¡6 and ¡3°C. On the other hand, frost injury temperature oscillated between ¡18 and ¡7°C. Our results suggest that grasses exhibit freezing tolerance as their main cold resistance mechanism. Since grasses grow at ground level, where greatest heat loss takes place, tolerance may be related to this life form as reported for other small life forms.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Freezing tolerance in grasses along an altitudinal gradient in the Venezuelan Andes

2006

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“…Ko¨rner 1999), though, arguably, the frost resistance of tropical alpine plant species have attracted more attention (e.g. Beck et al 1984;Goldstein et al 1985;Azocar et al 1988;Squeo et al 1991;Lipp et al 1994;Rundel et al 1994;Rada et al 2001).…”

Section: Introductionmentioning

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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“…Azócar et al (1988) found that the miniature rosette Draba chionophilla tolerates freezing, surviving ice formation in its leaf tissues. These authors suggest that plants growing close to the ground must tolerate freezing in order to survive these environments, while those growing away from the ground, i.e.…”

Section: Introductionmentioning

confidence: 99%

Freezing avoidance mechanisms in juveniles of giant rosette plants of the genus Espeletia

García-Varela

Rada

2003

Acta Oecologica

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Along soil-air gradients in tropical high mountains, plants growing at soil level tolerate frost while those growing well above ground, including all species in the genus Espeletia, use freezing avoidance mechanisms to survive low nighttime temperatures. The question that arises and the objective of this work were: What are the low temperature resistance mechanisms in giant rosettes when they are within the juvenile stages, i.e. closer to the ground? Juveniles of Espeletia spicata and Espeletia timotensis, dominant plants of the high Venezuelan Andes, were chosen for this study. To determine resistance mechanisms for these species, air and leaf temperatures were recorded in the field in 24 h cycles, while thermal analysis and injury temperature were determined in the laboratory. Both E. spicata and E. timotensis juveniles depend on avoidance mechanisms through a high supercooling capacity, permitting leaves to resist low nighttime temperatures. Minimum leaf temperatures were -4.9 and -5.1°C, for E. spicata and E. timotensis, respectively, occurring during the dry season. Ice formation occurred at -14.3 and -15.3°C for E. spicata and E. timotensis, respectively. Injury occurred at approximately -15°C in both species. Low temperature resistance mechanisms in juveniles are similar to those in adult plants.

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Freezing tolerance in Draba chionophila, a ?miniature? caulescent rosette species

Cited by 36 publications

References 14 publications

Freezing tolerance in grasses along an altitudinal gradient in the Venezuelan Andes

Freezing tolerance in grasses along an altitudinal gradient in the Venezuelan Andes

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

Freezing avoidance mechanisms in juveniles of giant rosette plants of the genus Espeletia

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