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Patricia Boucher and Benoît Côté Macdonald Campus, McGill University
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tarix | 04.08.2018 | ölçüsü | 94 Kb. | | #60816 |
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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 factors - Geology
- Texture
- Thickness
- Slope
- Drainage
- Soil flora and fauna etc.
The forgotten: nutrient immobilization
Sustainability of forest nutrition Linked to exportations of nutrients - Soils
- Leaf litter
- Tree biomass
- Natural losses (leaching, denitrification etc)
Rate vs Mass Nutrient pools at maturity 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? 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 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 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 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 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
Forest sampling
Rate of nutrient immobilization (g/m2/yr)
K concentrations (mg g-1)
Ca concentrations (mg g-1)
Mg concentrations (mg g-1)
Tissue proportion (v/v)
Immobilization rate vs DBH
Ca immobilization rate vs Age
Ca immobilization vs DBH
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) 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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