Article

Intercambio gaseoso en dos especies de plantas alto andinas de Chile central: efecto de la asociación a plantas en cojín [Gas exchange in two high andean plant species of central Chile: effect of the association with cushion plants]

Ecologia Austral 06/2005; 15(1):49-58.
Source: OAI

ABSTRACT

It has been proposed that on stressful environments as high mountain habitats, interactions between species of plants would tend to be of the positive type, increasing in intensity and frequency when resources in the environment become more limited. In this work, we studied the microclimatic modifications produced by cushions of Laretia acaulis species and its effects on the physiological performance of two associated species of the high mountain community located at 2800 m.a.s.l. in Los Andes of central Chile: Taraxacum officinale and Euphorbia collina, which frequently grow within and outside the cushions respectively. Gas exchange measures were taken in order to assess the effects caused by the microclimatic modifications done by cushions plants. We demonstrated that individuals of T. officinale that grow within cushions displayed, unlike their co-specifics in open spaces, a greater net photosynthesis rate. E. collina did not show differences in the rate of net photosynthesis between individuals present within and outside cushions. Only T. officinale displayed a greater rate of photosynthesis in the microsite where it is frequently distributed (within cushions). The effect of association with a nurse (e.g. cushion plants) for large biomass species, such as E. collina, could be less beneficial due to the competition for resources and space; this would explain why E. collina is more frequently found in open spaces.

Download full-text

Full-text

Available from: Ernesto Iván Badano, Feb 03, 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: The characteristics of corona discharge in needle to plane electrodes have been simulated by a two-dimensional fluid method. It was assumed that the transport coefficients of nitrogen gas were only the function of reduced electric field. In this discharge mechanism, Townsend first ionization and a secondary electron emission were considered. The spatio-temporal distributions of electron and ion densities at three discharge steps were obtained by solving continuity equations using FCT algorithm. This paper also describes the effect of space charge on the electric field distribution
    No preview · Conference Paper · Feb 2001
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Positive interactions among native plant species are common in alpine habitats, particularly those where one species (nurse plant) generates microclimatic conditions that are more benign than the surrounding environment, facilitating the establishment of other species. Nonetheless, these microclimatic conditions could facilitate the establishment of non-native species as well. A conspicuous component of the alien alpine flora of the central Chilean Andes is the perennial herb Taraxacum officinale agg. (dandelion). In contrast to other alien species that are restricted to human-disturbed sites, T. officinale is frequently observed growing within native plant communities dominated by cushion plants. In this study we evaluated if T. officinale is positively associated with the cushion plant Azorella monantha. Via seedling survival experiments and gas-exchange measurements we also assessed the patterns of facilitation between cushions and dandelions, and explore the potential mechanisms of invasion by dandelions. T. officinale grows spatially positively associated with cushions of A. monantha. Survival of seedlings, as well as their net-photosynthetic rates and stomatal conductance, were higher within cushions than in open areas away from them, suggesting that the microclimatic modifications generated by this native cushion facilitates the establishment and performance of a non-native invasive species. Our results, as well as other recent studies, highlight the role of native communities in facilitating rather than constraining non-native plant invasions, particularly in stressful habitats such as alpine environments.
    Full-text · Article · Dec 2005 · Perspectives in Plant Ecology Evolution and Systematics
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Aim To integrate the effects of ecosystem engineers (organisms that create, maintain or destroy habitat for other species) sharing the same archetype on species diversity, and assess whether different engineer species have generalized or idiosyncratic effects across environmentally similar ecosystems. Location High-Andean habitats of Chile and Argentina, from 23° S to 41° S. Methods We measured and compared the effects of eight alpine plants with cushion growth-form on species richness, species diversity (measured as the Shannon–Wiener index) and evenness of vascular plant assemblages across four high-Andean ecosystems of Chile and Argentina. Results The presence of cushion plants always increased the species richness, diversity (measured as the Shannon–Wiener index) and evenness of high-Andean plant assemblages. However, while the presence of different cushion species within the same ecosystem controlled species diversity in the same way, these effects varied between cushion species from different ecosystems. Main conclusions Results consistently supported the idea that increases in habitat complexity due to the presence of ecosystem engineers, in this case cushion plants, would lead to higher community diversity. Results also indicate that effects of the presence of different cushion species within the same ecosystem could be generalized, while the effects of cushion species from different ecosystems should be considered idiosyncratic.
    Full-text · Article · Feb 2006 · Journal of Biogeography
Show more