Tropical-Alpine Life-Forms of Vascular Plants

Hedberg, Inga; Hedberg, Olov

doi:10.2307/3544006

Cited by 134 publications

(108 citation statements)

References 9 publications

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“…This stem holds a large central parenchymatic pith and is protected by a large layer of marcescent leaves. It is interesting to point out that this life form, presenting very similar structures, has evolved in other ---tropical high mountain regions of the world (Hedberg and Hedberg 1979, Halloy 1983, Smith and Young 1987, Bussmann 2006, suggesting that they have developed as a response to a tropical environment characterized by extreme daily temperature fluctuations, frequent night frosts, seasonal and daily water availability limitations and high incoming radiation inputs.…”

Section: Introductionmentioning

confidence: 87%

Water relations and gas exchange in Coespeletia moritziana (Sch. Bip) Cuatrec., a giant rosette species of the high tropical Andes

Rada¹,

Azócar²,

Rojas-Altuve³

2012

Photosynt.

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Giant rosettes are ones of the most striking features of the vegetation in the high tropical Andes, with Coespeletia moritziana reaching the highest altitudes up to 4,600 m a.s.l. Different from other giant rosettes, this species grows on rock outcrops with poorly developed soils and where water availability may be limited. Two questions are addressed in this study: How does this species respond in terms of water relations to maintain favorable gas-exchange conditions? Considering that adult plants rely on a water-reserving central pith, how do early stages respond to this environment´s extreme conditions? Water relations and gas-exchange studies were carried out on juveniles, intermediate and adult C. moritziana plants during wet and dry seasons in Páramo de Piedras Blancas at 4,200 m a.s.l. Adult plants maintained higher leaf water potentials (Ψ L ) during the wet season, however, no differences between stages were found for the dry season. Minimum dry season Ψ L were never near the turgor loss point in any of the stages. Juveniles show a more strict stomatal control during the dry season to maintain a favorable water status. Net photosynthesis significantly decreased in intermediate and juvenile stages from wet to dry seasons. Our results suggest that C. moritziana resists more extreme conditions compared to other Andean giant rosettes.

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Section: Introductionmentioning

confidence: 87%

Water relations and gas exchange in Coespeletia moritziana (Sch. Bip) Cuatrec., a giant rosette species of the high tropical Andes

Rada¹,

Azócar²,

Rojas-Altuve³

2012

Photosynt.

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“…The peculiar life forms of the pâramos have been discussed in detail by Cuatrecasas (1968) and Hedberg and Hedberg (1979). The latter point out should probably be considered as a distinct life-form.…”

Section: Hybridizationmentioning

confidence: 99%

“…In addition to life-form, most piramo plants exhibit other modifications such as stiff, small, thickened leaves (sclerophylly) and some sort of covering or indûment, such as a thick cuticle or woolly hairs (Hedberg and Hedberg, 1979). These adaptations are probably related to reduction in transpiration rate and resistance to frost damage.…”

Section: Hybridizationmentioning

confidence: 99%

“…(Anderson and McNaughton, 1973) but has not been studied in tropical-alpine plants. Hedberg and Hedberg (1979) have shown how the tropical-alpine life-forms are adaptive in terms of temperature insulation and maintenance of water balance, but rigorous ecophysiological studies have not been attempted. The soil in areas where Chusquea species grow is cool but not frozen.…”

Section: Hybridizationmentioning

confidence: 99%

“…Mean annual temperature for paramos ranges from about 13 to 5 C, decreasing with altitude (Cuatrecasas, 1968;Walter and Medina, 1969;Cleef, 1981;Schubert, 1979;Lauer, 1979;Hedberg and Hedberg, 1979).…”

Section: Hybridizationmentioning

confidence: 99%

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Systematics of Chusquea section Chusquea, section Swallenochloa, section Verticillatae, and section Serpentes (Poaceae: Bambusoideae)

Clark

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Structural adaptations in plants from the humid equatorial Andes indicate a trade‐off between hydraulic transport efficiency and safety

Soukup

Pecková

Ježková

et al. 2021

American J of Botany

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PremiseEnvironmental gradients of mountains are reflected in traits that are common to high‐elevation plants worldwide. Closely related species of Senecio from the equatorial Andes grow as broad‐leaved climbers in montane forests, basal broad‐leaved rosette herbs in azonal marshy habitats, and ascending, narrow‐leaved subshrubs in high‐elevation páramo. Habitat variation along the elevational gradient enables testing whether modifications in leaf and stem functional traits among species were driven by contrasting environmental conditions.MethodsWe used quantitative analyses to describe changes in morphological and anatomical traits of leaves and stems in 10 species from various habitats. We applied univariate (linear regression, hierarchical ANOVA) and multivariate (NMDS ordination, permutational MANOVA) techniques to examine the correlation of traits with the species' habitats and elevation.ResultsSpecies from the humid and frost‐free montane forest develop xylem optimized for transport efficiency by increasing the internal diameter and length of the conduits. In contrast, páramo species are optimized toward hydraulic safety by producing narrower conduits and are more likely to prevent the risk of frost‐induced cavitation. Moreover, species from the high‐elevation páramo habitats present a set of water‐transport‐related anatomical traits of leaf lamina, allowing for efficient regulation of transpiration losses.ConclusionsMorphological and anatomical traits of leaves and stems in species of Senecio inhabiting montane forests and high‐elevation páramo in the equatorial Andes demonstrate a trade‐off between hydraulic safety and efficiency of water transport.

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Tropical-Alpine Life-Forms of Vascular Plants

Cited by 134 publications

References 9 publications

Water relations and gas exchange in Coespeletia moritziana (Sch. Bip) Cuatrec., a giant rosette species of the high tropical Andes

Water relations and gas exchange in Coespeletia moritziana (Sch. Bip) Cuatrec., a giant rosette species of the high tropical Andes

Systematics of Chusquea section Chusquea, section Swallenochloa, section Verticillatae, and section Serpentes (Poaceae: Bambusoideae)

Structural adaptations in plants from the humid equatorial Andes indicate a trade‐off between hydraulic transport efficiency and safety

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