scholarly journals Mechanosensing of stem bending and its interspecific variability in five neotropical rainforest species

2009 ◽  
Vol 105 (2) ◽  
pp. 341-347 ◽  
Author(s):  
C. Coutand ◽  
M. Chevolot ◽  
A. Lacointe ◽  
N. Rowe ◽  
I. Scotti
Keyword(s):  
Interspecific Variability ◽  
Stem Bending ◽  
Neotropical Rainforest

Growth strategies of clonal palms (Arecaceae) in a neotropical rainforest, Yasuni, Ecuador

2000 ◽  
Vol 48 (2) ◽  
pp. 167 ◽  
Author(s):  
Jens-Christian Svenning
Keyword(s):  
Light Availability ◽  
Common Species ◽  
Clonal Reproduction ◽  
Growth Strategy ◽  
Stem Diameter ◽  
Growth Strategies ◽  
Strong Constraint ◽  
Trade Off ◽  
Stem Bending ◽  
Neotropical Rainforest

Growth strategies of clonal palms were studied in old-growth tropical rainforest in Yasuní, Amazonian Ecuador. Genet structure, clonal and sexual fecundity, and light availability were investigated for 188 genets totalling 1256 ramets and 10 species. Negative relationships between risk of stem bending and stem diameter and between stem diameter and number of large ramets per genet were found. Recruitment of thick-stemmed species occurred in better-lit microsites than where the smaller species occurred. The three most common species were studied in more detail. Clonal and sexual fecundity were only related to light availability in one species each. No general trade-off between sexual and clonal reproduction was found. Sexual fecundity was related to size in all three species, while clonal fecundity was so only in one species. Overall, the results suggest that light availability poses a strong constraint on the evolution of growth strategies in clonal understorey palms, while the resource cost of sexual reproduction is not high enough to result in a general trade-off between sexual and clonal reproduction. It is also concluded that in understorey palms clonal growth is more a growth strategy than a dispersion-propagation strategy.

Beech sapling architecture following small and medium gap disturbances in silver fir-beech old-growth forests in Slovenia

2005 ◽  
Vol 156 (12) ◽  
pp. 481-486 ◽  
Author(s):  
Jurij Diaci ◽  
Lahorka Kozjek
Keyword(s):  
Light Intensity ◽  
Quality Characteristics ◽  
Stem Length ◽  
Silver Fir ◽  
Beech Forests ◽  
Vertical Growth ◽  
Relative Light Intensity ◽  
Stem Bending ◽  
Negative Effect

The objective of our research was to examine the effect of canopy shading on beech sapling architecture in the oldgrowth silver fir-beech forests of Pecka and Rajhenavski Rog. In August 2003 we sampled one plot (352 m2) in a large gap in Pecka, which was a result of a strong windstorm in 1983, and eight small gaps (26–78 m2) with similar sapling heights (3.8–8 m). A ground view of each gap was drawn including the characteristics of gap border trees and the density of separate sapling layers was recorded. The height and diameter were measured for each sapling, as well as the following quality characteristics on selected dominant saplings: width of the crown,number of larger branches and knots (>1/3 DBH), intensity of stem bending, deviation from vertical growth, number of terminal shoots, and the type of damage. The results show a negative effect of high canopy shading (estimated relative light intensity was below 5%) on the architectural quality of saplings. A lower overall density of saplings, greater intensity of bending and deviation from vertical growth, a shorter stem length without branches, a larger number of saplings with two terminal shoots, and a larger number of damaged saplings were observed in small gaps.

Australian endemic Drosophila I. Tasmania and Victoria, including descriptions of two new species

1977 ◽  
Vol 25 (2) ◽  
pp. 249 ◽  
Author(s):  
PA Parsons ◽  
IR Bock
Keyword(s):  
New South ◽  
Intraspecific Variability ◽  
Distribution Patterns ◽  
Progressive Reduction ◽  
Upland Forest ◽  
Interspecific Variability ◽  
South Wales ◽  
Forest Regions ◽  
Southern Species ◽  
Marginal Habitats

The endemic Drosophila fauna of southern Australia consists principally of species of the typically Australian subgenus Scaptodrosophila. In Tasmania and Victoria (but less so further north), the inornata group of species within the subgenus predominates. With one exception, none of the southern species is found further north than the upland forest regions of the Queensland-New South Wales border, this being the most northern extension of floral elements of the temperate rain forests of the south. Species diversities increase with decreasing latitude, presumably because of the dependence of Drosophila species on the flora which itself becomes more diverse with decreasing latitude. Evidence is presented for a progressive reduction of niches available or exploited with increasing latitude. In very marginal habitats interspecific variability is low, paralleling low genetic intraspecific variability often found in such habitats. Species distributions are probably highly dependent upon density-independent factors of the climate, so that past climatic shifts would have been important in leading to distribution patterns found today of Drosophila populations in 'insular islands of vegetation' surrounded by unsuitable habitats.

scholarly journals Factors driving diversity and succession of diatom assemblages in a Neotropical rainforest stream

2018 ◽  
Vol 54 ◽  
pp. 30 ◽  
Author(s):  
Jhon Charles Donato Rondón ◽  
Yaira Ayarith Abuhatab Aragón
Keyword(s):  
Environmental Factors ◽  
Solar Radiation ◽  
Shannon Index ◽  
Diatom Assemblages ◽  
Fluvial Systems ◽  
Neotropical Streams ◽  
Biogeographic Region ◽  
Nitrate Concentrations ◽  
Taxonomic Changes ◽  
Neotropical Rainforest

This study assessed short-term succession and related changes in diversity and succession of benthic diatom assemblages in a tropical rainforest stream in the biogeographic region of Chocó, Colombia. Diatom colonization in situ was studied over a 60-day period, in which we analyzed the number of valves and the taxonomic changes. The Shannon index ranged from 2.06 to 3.02 bits. A total of 127 species were identified and the most abundant were acidophilic species such as Eunotia intermedia, E. veneris, E. bilunaris var. mucophila, E. pirla and E. bilunaris. A Detrended Canonical Correspondence Analysis (DCCA) was used to explore the succession of diatom assemblages and its driving environmental factors. The DCCA explained 74.1% of the correlation between environmental variables and diatom species and 16.2% of the data variance. The species fell into four groups, the first group (Eunotia incisa, Frustulia saxonica, Fragilaria capucina var. acatu, among others) was related to lower nitrate concentrations, acidic pH and lower water temperature. The second group (Fragilaria capensis, Gomphonema olivaceum, Cymbella gracilis, among others) was associated to higher alkalinity and lower solar radiation availability. The third group (Nitzschia obtusa, N. amphibia, Naviculadicta vitabunda, Navicula cryptocephala, among others) was related to lower phosphate, higher nitrate concentrations, lower pH, and higher temperatures. The fourth group (Eunotia soleirolli, Frustulia vulgaris and F. rhomboides) was associated with higher solar radiation and lower alkalinity. These results underscore the importance of diatom diversity in Neotropical streams and the relevance of small variations in environmental factors on the composition of reference assemblages of Neotropical fluvial systems.

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