| dc.contributor.advisor | Gradstein, Robbert Prof. Dr. | |
| dc.contributor.author | Gehrig-Downie, Christine | |
| dc.date.accessioned | 2013-11-06T10:04:36Z | |
| dc.date.available | 2013-11-06T10:04:36Z | |
| dc.date.issued | 2013-11-06 | |
| dc.identifier.uri | http://hdl.handle.net/11858/00-1735-0000-0001-BC27-3 | |
| dc.identifier.uri | http://dx.doi.org/10.53846/goediss-4101 | |
| dc.language.iso | eng | de |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | |
| dc.subject.ddc | 570 | de |
| dc.title | Epiphyte diversity and microclimate of the tropical lowland cloud forest in French Guiana | de |
| dc.type | doctoralThesis | de |
| dc.contributor.referee | Gradstein, Robbert Prof. Dr. | |
| dc.date.examination | 2013-05-30 | |
| dc.description.abstracteng | Lowland cloud forests are well known from temperate regions, e.g. the
coasts of California and northern Chile (Bruijnzeel 2001), but in the
Tropics have remained uninvestigated. We tested the hypothesis that
tropical lowland cloud forest (LCF) and lowland rain forest (LRF) exist as
distinct forest types with a higher abundance of epiphytes in LCF and
differing in epiphyte species composition and microclimate. Furthermore,
these forest types seem to occur in close proximity to one another, with
LCF in valleys and LRF on adjacent slopes.
To validate this hypothesis, we compared epiphyte diversity and
abundance at two localities in Central French Guiana (Saül, Nouragues
Nature Reserve). Using the single rope technique (ter Steege &
Cornelissen 1988), we climbed 48 canopy trees from putative LCF and
LRF during a 6 month field trip to French Guiana. On each of the 48 target
trees, we removed epiphytes growing in 24 sample plots of 600 cm².
The plots were positioned at each cardinal direction in six height zones
(Johansson 1974, Cornelissen & ter Steege 1989): trunk base, lower
trunk, upper trunk, lower canopy, middle canopy, and outer canopy. Biomass
of epiphytic angiosperms, pteridophytes, lichens and bryophytes
was determined and three groups of epiphytic plants identified at species
level: macrolichens, filmy ferns and liverworts. Trees were classified as
belonging either to LCF or LRF based on geography and validated by microclimate
measurements. Species were identified using appropriate
methods for the different taxa, and overall forest species composition
evaluated for each forest type and statistically compared.
In total we found 39 (morpho-) species of macrolichens, 9 species of
Hymenophyllaceae, and 129 liverwort species. LCF contained a significantly
higher mean species number per tree for both liverworts (LCF: 33.6; LRF: 25.0) and Hymenophyllaceae (LCF: 2.4; LRF: 0.3) than LRF.
Moreover, 8 species of Hymenophyllaceae and 21 of liverworts were statistically
determined as indicator species for LCF. These indicators of LCF
included shade epiphytes and generalists that also occur in montane forests.
As LCF is more humid than LRF, the differences in liverwort and
filmy fern diversity can be attributed to the greater atmospheric water
content. Although the number of macrolichen species per tree was similar
in both forest types, lichens with cyanobacterial photobionts
(cyanolichens) were 2.5 times more common in LCF. Cyanolichens are
known to prefer humid habitats and this study showed that they are
good indicators for LCF. The observed differences in species diversity of
liverworts, filmy ferns and cyanolichens support the hypothesis that LCF
and LRF contain distinguishable epiphytic biodiversity, a finding which is
further supported by the measurement of higher overall epiphyte biomass
in LCF and more tree surface area covered by epiphytes (70 % in
LCF, 15 % in LRF).
Species composition differed greatly in all height zones for all studied
groups of epiphytes. Hygrophilous taxa (shade epiphytes) were more
common in LCF, while LRF harbored more xeric taxa (outer canopy specialists).
Moreover, comparison of the vertical distribution of epiphyte
species in LRF and LCF showed an upward shift of certain species of lichens,
bryophytes and ferns inhabiting lower strata in LRF towards higher
strata in LCF.
It had been previously observed that morning fog was present in
LCF of Saül (Montfoort & Ek 1990). Fog can lead to higher humidity by
providing a surplus of liquid water. To investigate whether there was an
increased incidence of fog in LCF over LRF, we measured air humidity,
calculated vapor pressure deficit, and frequency and duration of fog. LCF
plots were more humid than LRF plots during both wet and dry season.
LCF experienced higher overall mean air humidity, while high humidity
events occurred both more frequently and longer than in LRF. The overall
higher humidity is caused by fog formation in LCF at night; at early morning the moist air lifts into the canopy and acts as a radiation shield.
Vapor pressure deficit in LCF was calculated to be lower than in LRF,
especially in the early morning and significantly longer in duration. The
prolonged availability of high air humidity in LCF and the additional input
of liquid water through fog enhance epiphyte growth and influence
species composition and diversity in LCF by shortening the desiccation
period and lengthening the period of photosynthetic activity of the plants. | de |
| dc.contributor.coReferee | Kessler, Michael Prof. Dr. | |
| dc.contributor.thirdReferee | Bergmeier, Erwin Prof. Dr. | |
| dc.contributor.thirdReferee | Behling, Hermann Prof. Dr. | |
| dc.contributor.thirdReferee | Kreft, Holger Prof. Dr. | |
| dc.subject.eng | epiphytes | de |
| dc.subject.eng | Hymenophyllaceae | de |
| dc.subject.eng | filmy ferns | de |
| dc.subject.eng | macrolichens | de |
| dc.subject.eng | liverworts | de |
| dc.subject.eng | microclimate | de |
| dc.subject.eng | tropical lowland cloud forest | de |
| dc.subject.eng | tropical lowland rain forest | de |
| dc.subject.eng | biomass | de |
| dc.subject.eng | fog | de |
| dc.subject.eng | diversity | de |
| dc.subject.eng | French Guiana | de |
| dc.identifier.urn | urn:nbn:de:gbv:7-11858/00-1735-0000-0001-BC27-3-9 | |
| dc.affiliation.institute | Biologische Fakultät für Biologie und Psychologie | de |
| dc.subject.gokfull | Biologie (PPN619462639) | de |
| dc.identifier.ppn | 770939538 | |
| dc.creator.birthname | Gehrig | |