The influence of humidity, nutrients and light on the development of the epiphytic bromeliad Tillandsia guatemalensis L.B. Smith
In the highlands of Chiapas, rapid habitat destruction and alteration threaten the survival of epiphytic populations. One of the presumed effects of the transformation of the forests is an increase in border-type and open vegetation with more severe desiccation than in the nucleus of primary forest. Hence we expect that in particular populations of mesic epiphytic species should be affected. In this study we focus on the role of water availability during the development of a population of the mesic C3 green tank-bromeliad, TiUandsia guatemalensis. that is widespread in the region. The climate in Chiapas is characterised by a pronounced dry season from November up to April with an average monthly precipitation <30 mm. It is during the dry season that the seeds of T. guatemalensis are released. Germination in the field occurred some seven weeks after the beginning of the rains and was highly successful (over 93%, an observation confirmed in the laboratory). In our field experiment many of the tiny seedlings disappeared before they could anchor themselves to the substrate and appeared to be flushed off by torrential rains. In a naturally established population of well anchored individuals over half of all seedlings died during the dry season. High seedling mortality may also be deduced from the size-class structure of a natural population. Seedling mortality on bark derived from the tree base up to a height of 1.3 m of bigger trees is similar on two species of oak as compared to two species o f pine. Bark from these origins, also showed a high water retaining capacity. In the case of oaks, however, bark derived from higher up the tree absorbed and released a larger amount o f water per surface area and released water during a longer period in the dry season than the bark of Pinus oocarpa var. ochoterenai trees from similar positions within the host tree.
| Main Authors: | , , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Published: |
San Cristóbal de Las Casas, Chiapas, México El Colegio de la Frontera Sur
1997
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| Subjects: | Tillandsia guatemalensis, Dinámica de la población, Bosques de coníferas, Bromelia, Humedad, Frosur, |
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