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    Author(s): Benjamin J. Crain; Raymond L. Tremblay
    Date: 2017
    Source: International Journal of Plant Sciences
    Publication Series: Scientific Journal (JRNL)
    Station: International Institute of Tropical Forestry
    PDF: Download Publication  (609.0 KB)


    Premise of research. Tropical epiphytes are susceptible to climatic changes, as evidenced by documented population declines, range contractions, and range shifts; however, physiological changes in individual plants may also be indicative of deteriorating climate conditions. Consequently, physiological analyses of tropical epiphytes whose natural habitats are constrained by climatic conditions are warranted to evaluate their responses to potential changes in these conditions, to assess their vulnerability, and to guide conservation actions. Methodology. Here we investigate photosynthetic processes in Puerto Rican Lepanthes species, a group of Neotropical epiphytic orchids, as a model system to determine whether altered microclimate conditions elicit adverse physiological responses. We tested for differences in chlorophyll fluorescence, measured as Fv/Fm, as an indication of plant stress under modified temperature, humidity, and air vapor pressure deficit. Pivotal results. Mean Fv/Fm was positively correlated with mean relative humidity and negatively correlated with mean temperature and air vapor pressure deficit. Collectively, plants exposed to altered microclimate conditions had significantly lower mean Fv/Fm than plants in unaltered conditions. Plants in altered microclimate conditions were also more likely to exhibit declines in Fv/Fm over time, and they exhibited greater reductions in Fv/Fm over the course of the study. Conclusions. Epiphytic plant species such as Lepanthes could exhibit declines in Fv/Fm and experience greater stress in their natural habitats if current warming and drying trends continue as anticipated in Puerto Rico and elsewhere. Declining Fv/Fm is a robust indicator of plant stress, and several studies show that increased stress can promote leaf loss, limit reproduction, and lower survival rates. Thus, analyses of Fv/Fm can be advantageous for monitoring epiphytic orchids and other vulnerable plant species by offering a valuable means for detecting adverse responses to climate change.

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    Crain, Benjamin J.; Tremblay, Raymond L. 2017.Hot and Bothered: Changes in Microclimate Alter Chlorophyll Fluorescence Measures and Increase Stress Levels in Tropical Epiphytic Orchids. International Journal of Plant Sciences. 178(7): 503-511.


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    climate change, conservation physiology, Lepanthes (Orchidaceae), Fv/Fm, Puerto Rico, rare plant ecology

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