Patricia Boucher and Benoît Côté Macdonald Campus, McGill University



Yüklə 94 Kb.
tarix04.08.2018
ölçüsü94 Kb.
#60816


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

          • TIM = U - R
    • Where TIM = Tree nutrient immobilization
    • U = total nutrient uptake
    • R = total nutrient returns


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?

  • 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

  • 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 Age



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



Yüklə 94 Kb.

Dostları ilə paylaş:




Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©genderi.org 2024
rəhbərliyinə müraciət

    Ana səhifə