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Leaf Scale (leaf + scale)
Selected AbstractsTrophic control of grassland production and biomass by pathogensECOLOGY LETTERS, Issue 2 2003Charles E. Mitchell Abstract Current theories of trophic regulation of ecosystem net primary production and plant biomass incorporate herbivores, but not plant pathogens. Obstacles to the incorporation of pathogens include a lack of data on pathogen effects on primary production, especially outside agricultural and forest ecosystems, and an apparent inability to quantify pathogen biomass. Here, I report the results of an experiment factorially excluding foliar fungal pathogens and insect herbivores from an intact grassland ecosystem. At peak in control plots, 8.9% of community leaf area was infected by pathogens. Disease reduction treatment dramatically increased root production and biomass by increasing leaf longevity and photosynthetic capacity. In contrast, herbivory reduction had no detectable effects at the ecosystem or leaf scale. Additionally, biomass of foliar fungal pathogens in the ecosystem was comparable with that of insect herbivores. These results identify pathogens as potential regulators of ecosystem processes and promote the incorporation of pathogens into trophic theory. [source] Leaf respiratory CO2 is 13C-enriched relative to leaf organic components in five species of C3 plantsNEW PHYTOLOGIST, Issue 3 2004Cheng-yuan Xu Summary ,,Here, we compared the carbon isotope ratios of leaf respiratory CO2 (,13CR) and leaf organic components (soluble sugar, water soluble fraction, starch, protein and bulk organic matter) in five C3 plants grown in a glasshouse and inside Biosphere 2. One species, Populus deltoides, was grown under three different CO2 concentrations. ,,The Keeling plot approach was applied to the leaf scale to measure leaf ,13CR and these results were compared with the ,13C of leaf organic components. ,,In all cases, leaf respiratory CO2 was more 13C-enriched than leaf organic components. The amount of 13C enrichment displayed a significant species-specific pattern, but the effect of CO2 treatment was not significant on P. deltoides. ,,In C3 plant leaves, 13C-enriched respiratory CO2 appears widespread. Among currently hypothesized mechanisms contributing to this phenomenon, non-statistical carbon isotope distribution within the sugar substrates seems most likely. However, caution should be taken when attempting to predict the ,13C of leaf respiratory CO2 at the ecosystem scale by upscaling the relationship between leaf ,13CR and ,13C of leaf organic components. [source] Parameterization of the CO2 and H2O gas exchange of several temperate deciduous broad-leaved trees at the leaf scale considering seasonal changesPLANT CELL & ENVIRONMENT, Issue 2 2003Y. KOSUGI ABSTRACT A combined model to simulate CO2 and H2O gas exchange at the leaf scale was parameterized using data obtained from in situ leaf-scale observations of diurnal and seasonal changes in the CO2 and H2O gas exchange of four temperate deciduous broad-leaved trees using a porometric method. The model consists of a Ball et al. type stomatal conductance submodel [Ball, Woodrow & Berry, pp. 221,224 in Progress in Photosynthesis Research (ed. I. Biggins), Martinus-Nijhoff Publishers, Dordrecht, The Netherlands, 1987] and a Farquhar et al. type biochemical submodel of photosynthesis (Farquhar, von Caemmerer & Berry, Planta 149, 78,90, 1980). In these submodels, several parameters were optimized for each tree species as representative of the quantitative characteristics related to gas exchange. The results show that the seasonal physiological changes of Vcmax25 in the biochemical model of photosynthesis should be used to estimate the long-term CO2 gas exchange. For Rd25 in the biochemical model of photosynthesis and m in the Ball et al. type stomatal conductance model, the difference should be counted during the leaf expansion period. [source] Multi-scale phenotyping of leaf expansion in response to environmental changes: the whole is more than the sum of partsPLANT CELL & ENVIRONMENT, Issue 9 2009CHRISTINE GRANIER ABSTRACT The leaf is a multi-scale dynamic unit that is determined by mechanisms at different organizational scales (cell, tissue, whole leaf and whole plant) and affected by both internal (genotype) and external (environmental) determinisms. The recent development of phenotyping platforms and imaging techniques provides new insights into the temporal and spatial patterns of leaf growth as affected by those determinisms. Conclusions about the overriding mechanisms often depend on the considered organizational scale and of time resolution which varies from minutes to several weeks. Analyses of leaf growth responses to environmental conditions have revealed robust emerging properties at whole plant or whole leaf scales. They have highlighted that the control of individual leaf expansion is more complex than merely the sum of cellular processes, and the control at the whole plant level is more complex than the sum of individual leaf expansions. However, in many cases, the integrated leaf-growth variable can be simplified to a limited set of underlying variables to be measured for comparative analyses of leaf growth or modelling purposes. [source] | ||||||||||