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


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.

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Available from: Ernesto Iván Badano, Feb 03, 2014
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    • "Moreover, SIT1 has the lowest frequency. These findings can be interpreted as indirect evidence that in the dry Puna many species need some kind of facilitative interaction; this is consistent with the findings of many authors about arid and harsh environments (e.g., Valiente-Banuet et al. 1991; Haase et al. 1996; Tewksbury and Lloyd 2001; Molina-Montenegro et al. 2005). In the study case, tall grasses (mainly F. orthophylla and C. antoniana) are the most important nurse species because they have the highest number of spatially associated plants, while cushion species are of less importance. "
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    ABSTRACT: Plant–plant interactions play a key role in regulating the composition of communities. The outcome of interactions is the net effect of both positive and negative interactions. Positive interactions (facilitation) are defined as non-trophic interactions that increase the average individual fitness of at least one of the species involved. The study area was the Salinas and Aguada Blanca National Reserve, in the southern Peruvian Andes, composed of Festuca orthophylla grassland (dry Puna). The research goals were to ascertain whether spatial interactions act in this plant community, in order to determine whether beneficiary species have species–specific spatial associations. Our findings indicate that the most important nurses were the tall tussock species. A direct correlation was observed between the dimension of the F. orthophylla tussocks and the number of beneficiary species. Twelve species were closely associated with nurse species; five occurred in relation with nurse plants but without any preference for one of them; four species grew both isolated and in relationship with nurse plants and six species mostly grew isolated on bare soil. Because of the impact of grazers, some plants cannot grow on open ground; in fact, the species most in need of spatial interactions are those without avoidance strategies and/or with broad leaves. F. orthophylla is the core of a clumped spatial pattern of vegetation. The importance of spatial interactions for biodiversity conservation seems to be closely related to environmental amelioration and to grazer activity because plants of low palatability often serve as biotic refuges for palatable plants. KeywordsBeneficiary species–Biodiversity conservation–Facilitation processes–Nurse plants–Spatial interaction types–Species–specific relationship
    Alpine Botany 10/2011; 121(2):113-121. DOI:10.1007/s00035-011-0097-1 · 1.46 Impact Factor
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    • "Facilitation between plants is a non-consumptive interaction that benefits at least one of the participants (for review, see Callaway 1995). Facilitation is regarded as important in structuring plant communities, particularly in harsh environments such as deserts (Franco and Nobel 1988, Valiente- Banuet et al. 1991, Tirado and Pugnaire 2003), salt-marshes (Hacker and Bertness 1995, Callaway and Pennings 2000), rocky intertidal zones (Molina-Montenegro et al. 2005) and high-mountain ecosystems (Callaway et al. 2002). The most commonly reported facilitative interaction among plants is the " nurse effect, " where a species (the nurse) interacts with the environment to create more favourable micro-habitats than its surroundings for germination, establishment and survival of other plants (Valiente-Banuet et al. 1991, Suzán et al. 1996, Haase et al. 1996, 1997, Tewksbury and Lloyd 2001, Molina-Montenegro et al. 2005a). "
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    ABSTRACT: Facilitation by nurse plants is one of the most commonly reported interactions between plants and is regarded as an important factor in structuring plant communities. We used a meta-analysis to examine the generality of these effects, focusing on cushion plants, a common life-form occurring in high-Andean ecosystems. We targeted the following questions: (1) is there a generalized positive effect of cushions on other vascular plant species along the Andes? (2) do different species groups (i.e., annuals and perennials, natives and exotics) display different association responses to cushions? (3) does the nurse effect of cushions increase with environmental severity? Results indicated that the overall effect of cushions is positive, however these positive effects were more significant amongst exotic plants than in native plants; effects were only positive for perennial plants, and were notably negative for annuals. The positive effects of cushions also increased with physical stress, but only for perennial plants. These results allow us to suggest that as a whole cushions may be acting as keystone species that maintain the structure and diversity of high-Andean plant communities. Nevertheless, since cushions also positively affect the performance of exotic plants, we should be aware of their potential role in promoting biological invasions.
    Community Ecology 06/2009; 10(1):1-6. DOI:10.1556/ComEc.10.2009.1.1 · 1.21 Impact Factor
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    Electrical Machines and Systems, 2001. ICEMS 2001. Proceedings of the Fifth International Conference on; 02/2001
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