Published on January 19, 2008
Interspecific differences in rates of base cation immobilization in the stem of some hardwoods of eastern Canada: Interspecific differences in rates of base cation immobilization in the stem of some hardwoods of eastern Canada Patricia Boucher and Benoît Côté Macdonald Campus, McGill University Québec, Canada Soil - Tree System vs Nutrient availability: Soil - Tree System vs Nutrient availability Soil factors Geology Texture Thickness Slope Drainage Soil flora and fauna etc. Plant/species effects Uptake Roots Leaves Litter Roots Leaves Throughfall/stemflow The forgotten: nutrient immobilization: The forgotten: nutrient immobilization TIM = U - R Where TIM = Tree nutrient immobilization U = total nutrient uptake R = total nutrient returns Sustainability of forest nutrition: Sustainability of forest nutrition Linked to exportations of nutrients Soils Leaf litter Tree biomass Natural losses (leaching, denitrification etc) Rate vs Mass: Rate vs Mass Nutrient pools at maturity to measure exportation via exploitation Rates of nutrient immobilization in tree biomass before maturity Could be a more sensitive variable Could provide an earlier signal Could compare species at different ages Why hardwoods?: Why hardwoods? Conifers are reputed to be soil acidifiers Hardwoods can acidify soils even faster (Johnson and Todd 1990) Which hardwoods have the highest potential for soil acidification? American beech, sugar and red maple? Poplar, basswood, ash? Objectives: Objectives Assess the rate of base cation (K, Ca and Mg) immobilization in the stem of selected hardwoods of eastern Canada Establish relationships between rates of immobilization, and tree age and size Hypotheses: Hypotheses Trees of intermediate age and size will have maximum rates of nutrient immobilization Late-successional species (e.g. beech and maple) would have the highest overall rates of base cation immobilization Some species would show a weak/strong affinity for specific elements Study site: Study site Morgan Arboretum, McGill, Montreal Great Lakes - St. Lawrence forest Rich site Brunisol, pH 7 Sugar maple, basswood, white ash (40-100 yrs old) Poor site Podzol, pH 4.5 American beech, red maple, red oak (40-100 yrs old) Allometric equations: Allometric equations 3 trees per species were cut down (20, 30 and 40 cm in diameter) 5-10 cm thick discs were cut from the base of the stem and subsequent 3-m intervals to a stem diameter of 9 cm Discs were separated into heartwood, sapwood, transitional zone, bark Developed for sugar and red maple, beech, red oak, basswood and white ash Tree sampling: Tree sampling bark sapwood transition heartwood Forest sampling: Forest sampling 6 species sampled basswood, sugar maple & white ash beech, red oak & red maple 20-25 trees per species one increment core per tree (age and DBH) Area per tree = Projection of the crown to the ground Rate of nutrient immobilization (g/m2/yr): Rate of nutrient immobilization (g/m2/yr) Based on : tissue concentration (mg/g) wood density (g/cm3) stem volume (cm3) age (years) crown projection (m2) K concentrations (mg g-1): K concentrations (mg g-1) Species heartwood transition sapwood bark White ash 1.5b 1.5b 1.0c 2.9a Sugar maple 1.8b 0.65d 0.9c 2.8a Basswood 4.2a 0.9c 1.4b 1.6b Beech 0.7b 0.8b 0.6b 1.25a Red oak 0.8b 1.1a 1.1a 1.0a Red maple 1.1a 0.6b 0.55b 1.0a Ca concentrations (mg g-1): Ca concentrations (mg g-1) Species heartwood transition sapwood bark White ash 0.44c 0.45c 0.53b 17a Sugar maple 4.5b 1.0c 0.9c 20a Basswood 5.5b 1.1c 1.2c 16a Beech 0.8b 0.6b 0.7b 22a Red oak 0.4c 0.8b 0.9b 21a Red maple 1.3b 0.7c 0.8c 11a Mg concentrations (mg g-1): Mg concentrations (mg g-1) Species heartwood transition sapwood bark White ash 0.13c 0.12c 0.18b 1.5a Sugar maple 0.9a 0.19b 0.14c 0.9a Basswood 1.1a 0.2b 0.2b 1.2a Beech 0.2b 0.2b 0.2b 0.6a Red oak 0.03b 0.2a 0.3a 0.4a Red maple 0.3a 0.2b 0.1b 0.4a Tissue proportion (v/v): Tissue proportion (v/v) Slide18: K immobilization (kg tree-1) Slide19: Ca immobilization (kg tree-1) Immobilization rate vs Age: Immobilization rate vs Age Species K Ca Mg White ash -- --- --- Sugar maple + NS NS Basswood --- --- -- Beech NS NS NS Red oak NS NS + Red maple NS NS NS Immobilization rate vs DBH: Immobilization rate vs DBH Species K Ca Mg White ash NS NS NS Sugar maple +++ ++ +++ Basswood NS NS NS Beech ++ + ++ Red oak +++ +++ + Red maple +++ +++ +++ Slide22: Mg immobilization (kg tree-1) Ca immobilization rate vs Age: Ca immobilization rate vs Age Ca immobilization vs DBH: Ca immobilization vs DBH Conclusions: Conclusions Interspecific differences: Large beech and sugar maple immobilized more base cation per inch of DBH (generalists) White ash is high in K Red oak is low in Mg Nutrient, age, DBH relationships Immobilization rates decrease with age in early successional species on the rich site Immobilization rates increases with size in others Conclusions (continued): Conclusions (continued) Species growing together on a particular site are likely to develop different patterns of base cation immobilization over time that may contribute to an efficient utilization of site nutrients throughout stand development Generally difficult to rank species in terms of rates of nutrient immobilization
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