The Experts below are selected from a list of 24420 Experts worldwide ranked by ideXlab platform
B.d. Bricker - One of the best experts on this subject based on the ideXlab platform.
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Interspecific Variation in tree seedling establishment in canopy gaps in relation to tree density
Journal of Vegetation Science, 1995Co-Authors: Richard J Reader, T.e. Duralia, Stephen P Bonser, B.d. BrickerAbstract:Abstract. We tested whether Interspecific Variation in tree seedling establishment in canopy gaps was significantly related to Interspecific Variation in tree density, for seven deciduous forest tree species (Quercus alba, Hamamelis virginiana, Acer rubrum, Sassafras albidum, Quercus rubra, Prunus serotina, Ostrya virginiana). For each species, seedling establishment was calculated as the difference in seedling density before experimental gap creation versus three years after gap creation. In each of the six experimentally-created gap types (33 % or 66 % removal of tree basal area from 0.01-ha, 0.05-ha or 0.20-ha patches), differences in seedling establishment among species were significantly related to differences in their density in the tree canopy. A regression model with loge tree density as the independent variable accounted for between 93 % and 98 % of Interspecific Variation in seedling establishment. Our results provide empirical support for models of tree dynamics in gaps that assume seedling establishment depends on canopy tree density.
Kouki Hikosaka - One of the best experts on this subject based on the ideXlab platform.
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Mechanisms underlying Interspecific Variation in photosynthetic capacity across wild plant species
Plant Biotechnology, 2010Co-Authors: Kouki HikosakaAbstract:Photosynthetic capacity of leaves varies greatly among C3 species although they have the same photosynthetic metabolisms. Here we discuss mechanisms underlying Interspecific Variation in photosynthetic capacity. Within-species Variation in photosynthetic capacity is generally explained by nitrogen concentration because photosynthetic nitrogen-use efficiency (PNUE, photosynthetic capacity per unit leaf nitrogen) tends to be constant in each species. Among-species Variation, on the other hand, involves both Variations in nitrogen concentration and PNUE. Species with higher photosynthetic capacity have higher nitrogen concentration per mass and PNUE. Interspecific Variation in PNUE is attributable to CO2 diffusion in the leaves, nitrogen allocation to the photosynthetic apparatus and/or specific activity of photosynthetic enzymes. Previous studies have shown that Variations in mesophyll conductance and nitrogen allocation explain the Variation in PNUE. As new leaves are constructed by assimilated nitrogen and carbon, increased carbon assimilation rates are expected to dilute nitrogen in the leaves. However, this expectation contradicts the fact that photosynthetic capacity and nitrogen concentration is positively related with each other across species. This paradoxical dilution effect may be compensated by root activity, i.e. species with higher photosynthetic capacity have higher root activity to maintain higher leaf nitrogen concentrations.
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The role of Rubisco and cell walls in the Interspecific Variation in photosynthetic capacity.
Oecologia, 2009Co-Authors: Kouki Hikosaka, Aki ShigenoAbstract:Photosynthetic capacity is known to vary considerably among species. Its physiological cause and ecological significance have been one of the most fundamental questions in plant ecophysiology. We studied the contents of Rubisco (a key enzyme of photosynthesis) and cell walls in leaves of 26 species with a large Variation in photosynthetic rates. We focused on photosynthetic nitrogen-use efficiency (PNUE, photosynthetic rate per nitrogen), which can be expressed as the product of Rubisco-use efficiency (RBUE, photosynthetic rate per Rubisco) and Rubisco nitrogen fraction (RNF, Rubisco nitrogen per total leaf nitrogen). RBUE accounted for 70% of the Interspecific Variation in PNUE. The Variation in RBUE was ascribed partly to stomatal conductance, and other factors such as mesophyll conductance and Rubisco kinetics might also be involved. RNF was also significantly related to PNUE but the correlation was relatively weak. Cell wall nitrogen fraction (WNF, cell wall nitrogen per total leaf nitrogen) increased with increasing leaf mass per area, but there was no correlation between RNF and WNF. These results suggest that nitrogen allocation to cell walls does not explain the Variation in PNUE. The difference in PNUE was not caused by a sole factor that was markedly different among species but by several factors each of which was slightly disadvantageous in low PNUE species.
Stanley R Herwitz - One of the best experts on this subject based on the ideXlab platform.
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Interspecific Variation of bark water storage capacity of three deciduous tree species in relation to stemflow yield and solute flux to forest soils
Catena, 2005Co-Authors: Delphis F Levia, Stanley R HerwitzAbstract:Abstract The purpose of the study was to: (1) test if normative bark water storage capacities differed significantly among three co-occurring deciduous tree species; and (2) examine the extent to which stemflow production and resulting solute inputs in temperate deciduous forests are affected by bark water storage capacity. Normative bark water storage capacities were determined for: Betula lenta L. (sweet birch), Carya glabra Mill. (pignut hickory), and Quercus rubra L. (northern red oak). Using the computed normative bark water storage capacities, previously published allometric equations relating tree diameter to aboveground woody surface area, and stemflow yield and chemistry data from ten precipitation events, the influence of bark water storage capacity on stemflow production and solute inputs was examined. Results demonstrated normative bark water storage capacities differed significantly among the tree species examined. Quercus rubra was found to hold the most water and B. lenta the least. For a 30 cm diameter tree, normative bark water storage capacities ranged from approximately 100 l for B. lenta to 250 l for Q. rubra. Despite a higher normative bark water storage capacity, Q. rubra was computed to have the largest stemflow solute inputs. Differences in stemflow quantities as well as solute inputs were attributable to Interspecific Variation in bark morphology and branching architecture, characteristics that affect amount of storage and detention times. Bark water storage capacity is linked with the geoecology of temperate deciduous forests because stemflow volume and solute inputs are partly determined by bark water storage capacity.
Johannes Overgaard - One of the best experts on this subject based on the ideXlab platform.
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The capacity to maintain ion and water homeostasis underlies Interspecific Variation in Drosophila cold tolerance.
Scientific reports, 2015Co-Authors: Heath A. Macmillan, Jonas Lembcke Andersen, Shireen A. Davies, Johannes OvergaardAbstract:Many insects, including Drosophila, succumb to the physiological effects of chilling at temperatures well above those causing freezing. Low temperature causes a loss of extracellular ion and water homeostasis in such insects, and chill injuries accumulate. Using an integrative and comparative approach, we examined the role of ion and water balance in insect chilling susceptibility/ tolerance. The Malpighian tubules (MT), of chill susceptible Drosophila species lost [Na+] and [K+] selectivity at low temperatures, which contributed to a loss of Na+ and water balance and a deleterious increase in extracellular [K+]. By contrast, the tubules of chill tolerant Drosophila species maintained their MT ion selectivity, maintained stable extracellular ion concentrations, and thereby avoided injury. The most tolerant species were able to modulate ion balance while in a cold-induced coma and this ongoing physiological acclimation process allowed some individuals of the tolerant species to recover from chill coma during low temperature exposure. Accordingly, differences in the ability to maintain homeostatic control of water and ion balance at low temperature may explain large parts of the wide intra- and Interspecific Variation in insect chilling tolerance.
Colleen K. Kelly - One of the best experts on this subject based on the ideXlab platform.
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Interspecific Variation in seed size and safe sites in a temperate rain forest
New Phytologist, 2003Co-Authors: Christopher H. Lusk, Colleen K. KellyAbstract:Summary • The safe site concept could have utility in community ecology if predictive relationships between plant traits and safe site characteristics could be identified. Here we examine the proposal that the nature and relative abundance of safe sites are systematically related to seed size, in an assemblage of 17 woody species in a temperate forest. • We compared the degree of association of seedlings of each species with elevated microsites, and examined life-history correlates of this Variation. • Seed size explained 45% of Interspecific Variation in percentage of seedlings growing on logs and other elevated substrates. Neither specific leaf area nor an index of light requirements gave significant increases in explanatory power. Phylogenetically independent contrasts gave a similar, but weaker, relationship with seed size. Most small-seeded species were overrepresented on elevated microsites, whereas two large-seeded taxa were underrepresented on these substrates. Safe sites of small-seeded species were therefore more spatially restricted than those of large-seeded taxa, as elevated surfaces occupied only 8% of the forest floor. • Safe site differentiation may help to explain the wide range of seed size present within many communities, as well as species coexistence in forests.
