Browsing by Subject "canopy"

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  • Hartikainen, Saara M.; Jach, Agnieszka; Grane, Aurea; Robson, Thomas Matthew (2018)
  • Kellomäki, Seppo; Oker-Blom, Pauline (Suomen metsätieteellinen seura, 1983)
  • Pukkala, Timo; Kuuluvainen, Timo (Suomen metsätieteellinen seura, 1987)
  • Stam, Åsa Charlotta Sofia; Enroth, Johannes; Malombe, Itambo; Pellikka, Petri Kauko Emil; Rikkinen, Jouko Kalevi (2017)
    Transplant studies can provide valuable information on the growth responses of epiphytic bryophytes and lichens to environmental factors. We studied the growth of six epiphyte species at three sites in moist Afromontane forests of Taita Hills, Kenya. With 558 pendant transplants we documented the growth of the selected four bryophytes and two lichens over the time course of one year. The transplants were placed into the lower canopy of one forest site in an upper montane zone and two forest sites in a lower montane zone. Several pendant moss species grew very well in the cool and humid environment of the upper montane forest, with some transplants more than doubling their biomass during the year. Conversely, all transplanted taxa performed poorly in the lower montane zone, presumably because of the unfavorable combination of ample moisture but excessive warmth and insufficient light which characterizes lower canopy habitats in dense lower montane forests. The results demonstrate that transplantation studies with pendant transplants can be used for monitoring growth of nonvascular epiphytes in tropical forests. The start weight of 0.25 g for pendant transplants worked well and can be recommended for future studies.
  • Päivänen, Juhani (Suomen metsätieteellinen seura, 1974)
  • Kuusipalo, Jussi (Suomen metsätieteellinen seura, 1985)
  • Oker-Blom, Pauline (Suomen metsätieteellinen seura, 1986)
    In modeling canopy structure, a statistical approach is applied to assign the location and orientation of plant parts; the radiation field is described in terms of random variables and their distributions. A comparison of horizontally homogeneous stands and grouped forest stands showed that grouping reduced interception of radiation and increased spatial variation. In conifers, the grouping of needles into shoots and the effect of penumbra had an important influence on the distribution of radiation on the needle area.
  • Murakami, Mariana; Nunes Ramos, Flavio; Durand, Maxime; Ashton, Robert; Batke, Sven P. (2022)
    Forest canopies are incredibly complex self-maintaining biological structures. Conditions above and within the canopy can differ vastly, often resulting in a vertical gradient of microclimate conditions. Canopy epiphytic plants have to deal with climatic variability on much more variable scales compared to many other plant groups. The difficulty of sensor installation and their high cost can explain why it has been ignored in many studies on canopy epiphytes. Direct measurements of microenvironmental conditions are the only accurate way to assess specific intra-canopy environmental conditions, as there is also still a lack of methodologically and financially viable alternatives to allow the collection of this type of data. This study aims to make recommendations for the direct use of microclimate measurements in epiphyte research and to summarize key discussion points concerning the number and placement of sensors required for different types of epiphyte studies. In addition, we presented high-resolution field data from the United Kingdom, where we employed over 56 microclimate sensors, to demonstrate the spatial and temporal variability of radiation, temperature, and relative humidity (RH) in a tree canopy. Our data demonstrated that sensor height in the tree and leaf-set were the most important factors determining microclimate variability in the canopy. For the first time, we have made recommendations regarding the placement and number of sensors required in studies that specifically require the use of microclimate sensors in epiphyte studies in forest canopies.
  • Stam, Åsa Charlotta Sofia; Anttila, Jani; Pellikka, Petri Kauko Emil; Rikkinen, Jouko Kalevi (2020)
    We studied growth of three epiphytic bryophyte species in Kenya to determine their sensitivity to environmental changes. Bryophytes collected from a cool and moist upper montane forest were used to prepare 180 pendant transplants. Sixty transplants were placed in their natural habitat while 120 were transferred to two warmer and drier sites in a lower montane forest. After one year, all the transplants recovered from the lower mon-tane forest were transferred back to the upper montane forest. In the third year, half of the remaining transplants were left in their location, and half transferred to an eucalyptus plantation forest, both in the upper montane zone. After each year subsamples were taken from each group for growth measurements. The epiphytic bryophytes demonstrated considerable resilience during the experiment. They clearly suffered from the warm and dry conditions of the lower montane forest, but quickly recovered and then exhibited growth rates comparable to those of the controls. In the third year there was no statistical difference in the growth of transplants in their natural location and in the eucalyptus plantation. This indicates that the lack of suitable substrate is the primary factor limiting bryophyte biomass in plantation forests rather than unsuitable microclimate per se.