title: Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display

authors: Lusk, Christopher H.

subjects: Biomass distribution

abstract: Background and Aims The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. Methods This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LARd) was used to indicate plant light interception potential: LARd is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle.ResultsAngiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LARd was about twice that of conifers. Although specific leaf area was the most pervasive influence on LARd, differences in self-shading also significantly influenced LARd of large seedlings. Conclusions The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.

text: Seedlings of temperate rainforest conifer and angiosperm trees differ in leaf area display Background and Aims The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers. Methods This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LARd) was used to indicate plant light interception potential: LARd is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle.ResultsAngiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LARd was about twice that of conifers. Although specific leaf area was the most pervasive influence on LARd, differences in self-shading also significantly influenced LARd of large seedlings. Conclusions The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.

year: 2012

title: Macrophyte architecture affects the abundance and diversity of littoral microfauna

authors: Lucena-Moya, Paloma

subjects: zooplankton

abstract: We tested the hypothesis that structural complexity is an important factor influencing the abundance and taxon richness of microfauna (e.g., rotifers, copepods, cladocerans) in littoral habitats. Research on littoral microfauna has to date focused mainly on field observations, which commonly show microfauna have preference for some macrophytes over others. However, while such studies commonly conclude that macrophyte architecture is a major determinant of these variations, independent factors may also be responsible (e.g., differences in macrophyte ages, differences in macrophyte bed densities and the depth of the respective macrophyte beds sampled). We used artificial macrophytes with three levels of complexity to keep the surface area and mass of the substrate sampled constant, and to control for confounding factors not related to the complexity of the plants. Our results support the hypothesis that structural complexity is an important factor influencing abundance and taxon richness, independent of other potential confounding factors. Microfaunal (mainly rotifer) abundance and richness were generally greater on more complex artificial macrophytes, likely a result of more complex substrates (1) providing a greater variety of habitat, (2) supporting a greater concentration or variety of food and/or (3) affording greater protection against predators. Less mobile surface-associated (i.e., benthic/periphytic) taxa were found to discriminate among substrates, whereas the abundance and richness of planktonic species were not affected by complexity level. Relatively low abundances and taxon richness of microfauna recorded in control samples, which did not contain artificial macrophytes, supports the contention that vegetated areas sustain a higher abundance and variety of species than non-vegetated areas.

text: Macrophyte architecture affects the abundance and diversity of littoral microfauna We tested the hypothesis that structural complexity is an important factor influencing the abundance and taxon richness of microfauna (e.g., rotifers, copepods, cladocerans) in littoral habitats. Research on littoral microfauna has to date focused mainly on field observations, which commonly show microfauna have preference for some macrophytes over others. However, while such studies commonly conclude that macrophyte architecture is a major determinant of these variations, independent factors may also be responsible (e.g., differences in macrophyte ages, differences in macrophyte bed densities and the depth of the respective macrophyte beds sampled). We used artificial macrophytes with three levels of complexity to keep the surface area and mass of the substrate sampled constant, and to control for confounding factors not related to the complexity of the plants. Our results support the hypothesis that structural complexity is an important factor influencing abundance and taxon richness, independent of other potential confounding factors. Microfaunal (mainly rotifer) abundance and richness were generally greater on more complex artificial macrophytes, likely a result of more complex substrates (1) providing a greater variety of habitat, (2) supporting a greater concentration or variety of food and/or (3) affording greater protection against predators. Less mobile surface-associated (i.e., benthic/periphytic) taxa were found to discriminate among substrates, whereas the abundance and richness of planktonic species were not affected by complexity level. Relatively low abundances and taxon richness of microfauna recorded in control samples, which did not contain artificial macrophytes, supports the contention that vegetated areas sustain a higher abundance and variety of species than non-vegetated areas.

year: 2011

title: The Google Translator Toolkit and minority languages case study: Translating Moodle 2.0 into te reo Māori

authors: Manuirirangi, Hōri

abstract: This paper describes a case study where the Google Translator Toolkit (GTT) was used to undertake a large translation task involving a minority language. The task involved the translation of 50,000 interface terms of the Moodle learning management system into te reo Māori (the Māori language).  

The paper begins by describing how some minority languages are not in an environment where technology can be easily used for translations. It then suggests that te reo Māori however, is in a position to use technology and suggests some technologies that are suitable. The paper then briefly describes the GTT and the translation task that this tool was used for. The translators' feedback on the use of this technology in this environment is summarised and it appears that the GTT is suitable to be used by minority language translators.

text: The Google Translator Toolkit and minority languages case study: Translating Moodle 2.0 into te reo Māori This paper describes a case study where the Google Translator Toolkit (GTT) was used to undertake a large translation task involving a minority language. The task involved the translation of 50,000 interface terms of the Moodle learning management system into te reo Māori (the Māori language).  

The paper begins by describing how some minority languages are not in an environment where technology can be easily used for translations. It then suggests that te reo Māori however, is in a position to use technology and suggests some technologies that are suitable. The paper then briefly describes the GTT and the translation task that this tool was used for. The translators' feedback on the use of this technology in this environment is summarised and it appears that the GTT is suitable to be used by minority language translators.

year: 2011