Great Mountain Forest

Presented by Charlie Canham.

Location: Canaan Mountain Plateau in northwestern Connecticut, USA

Climate: Annual rainfall: ~ 1000 mm; Growing season: ~ 5 months

Soils: sandy, acidic, inceptisols and spodosols derived from glacial till (mica schist and gneiss bedrock)

Natural Disturbance Regime: wind.

Trees: Oak-northern hardwood forest, transitional between oak of S. New England and hardwoods of N. New England.

Dominant species:

• Beech (Fagus grandifolia)
• Eastern hemlock (Tsuga canadensis)
• Sugar maple (Acer saccharum)
• Yellow birch (Betula alleghaniensis)
• Red maple (Acer rubrum)
• White ash (Fraxinus americana)
• Black cherry (Prunus serotina)
• Red oak (Quercus rubra)
• White Pine (Pinus strobus)

Research: Currently focused on invasives Probably not going to continue to study small mammals there, but will do some more deer work.

British Columbia - Date Creek

Presented by Dave Coates.

Extensive climate characterization of BC exists.

Trees:
Dominant species

• Western hemlock (Tsuga heterophylla)
• Western redcedar (Thuja plicata)
• Amabilis fir (Abies amabilis)
• Subalpine fir (Abies lasiocarpa)
• Hybrid spruce (Picea x spp.)
• Lodgepole Pine (Pinus contorta var. latifolia)
• Paper Birch (Betula papyrifera)
• Black cottonwood (Populus balsamifera ssp. trichocarpa)
• Trembling aspen (Populus tremuloides)

Disturbance regime: Fire. Patch dynamics develop after 100-150 years. The Date Creek partial-cutting strategy is designed to replicate this.

Research: Answering management questions.

• 95% of BC forest is public land
• Forestry strategies are in flux right now - from clear-cutting to mixed-species stands using variable-retention cutting/partial cutting
• Management strategies are moving from agricultural model to ecosystem- or natural-disturbance model
• Forest companies and government must demonstrate sustainability - and it needs a scientific basis (thus the use of SORTIE)
• Current research focus - studying the very patchy structure that is left after partial cutting - how does that affect yield? Is it sustainable?

Quebec Temperate Forest

Presented by Marilou Beaudet.

Trees:
The forest is deciduous with variety of shade-tolerant and mid-shade-tolerant species.

Species:

• Sugar maple - dominant species
• Beech
• Yellow birch
• White ash
• Black cherry
• Red maple
• Many understory species - most abundant is striped maple

Research questions:

• Quantitative assessment of efects of various types of harvesting on species composition
• For a given pattern of tree removal - what's the effect of varying harvesting intensity?
• For given intensity - what's the effect of varying spatial configuration of harvesting?
• How do initial stand conditions affect how the given type of harvesting will influence forest response?

SORTIE is being used to evaluate management strategies for temperate deciduous forests. The most common type of harvesting is selection cutting - removal of all dbh classes. Group selection is also used - large gaps with low-intensity cutting between. Patch selection is rarely used. Management is often geared toward maximization of commercial species. The theory is that lower-intensity harvesting encourages sugar maple dominance (syrup harvest) and that higher-intensity favors yellow birch (sawlog and veneer production). But there is a worry that promoting a single harvest type will destroy species diversity.

New Zealand

Presented by Deb Wilson.

Site:Waitutu forest. The site is interesting because of its fertility gradient. It is composed of a series of old marine terraces; the terraces are most fertile in the lowlands and least fertile at higher elevations. The fertility gradient is thought to come from different hydrological systems and different ages.

Management goals: Management in New Zealand is not aimed at logging, but rather at the protection of threatened species and elimination of weeds and pests. There are no native land mammals in New Zealand except bats - so a big area of study is on introduced large herbivores and rats and mice.

Research questions: Do ecosystems recover after pest control? Present pest management is too simplistic. Current field projects are fertilization experiements, herbivore studies, and detailed mapping/seedling recruitment (limited).

Desired additions to the model: Effects of introduced animals and below-ground nutrient cycling.

Kentucky

Presented by Chris Tripler.

Research questions:
In coupling general circulation and biogeography models some assumptions arise:

• CO₂ will double over the next 100 years
• Global temperature will increase from 2 to 7 degrees C
• Barriers to tree migration are minimal
• Individual species responses are driven by water demand

Resulting predictions:

• Many species will move northward
• In particular, beech and sugar maple will be reduced
• Oak species will increase in importance

There are several pitfalls of large coupled models:

• No tree-tree interactions
• No spatial dynamics
• Species responses scale linearly
• Nearly impossible to validate - this is the impetus for current project

In order to study the predicted climate change, cities are being used as a surrogate. Reasons:

• Change in CO₂, temperature, N-deposition in cities matches predictions
• Comparative with rural forests
• Species performances obtainable
• Integrative response - differentiate species

Site: One urban plot, one rural. East-facing slopes, similar elevation and stand age, chestnut oak dominated, Tilsit soil series.

Current results: Urban saplings don't show serious variance in growth response to light. Sugar maples uniformly perform poorly.

Michigan

Presented by Rich Kobe.

Site: Fertility gradient across different glacial soils - outwash, ice contact, and moraine (low to high). This produces a tremendous variation in species composition along the gradient.

Research goal: What are the mechanisms that lead to this species sorting? Current studies are looking at soil resources - nutrients and soil moisture.

Current results: Nitrogen and exchangeable calcium increase from low to high fertility sites. Soil moisture exhibits a weak increase across fertility gradient from low to high - understanding water's role is problematic.

Likely important for species variability:

• Nitrogen
• Calcium
• Periodic water limitation (minimum water)

Possibly important:

• Magnesium
• Mean water availability (but weak trends)

Not likely to be important

• K
• P
• Mn

Quebec Boreal Forest

Presented by Christian Messier.

The goal for Canadian harvesting is emulation of natural disturbance. In some places, like British Columbia, the prominent disturbance is fire. However, in eastern Canada, fire much less common. Insect outbreak is a more reasonable goal for emulation.

Research:
Theoretical questions:

• What are the effects of insect defoliation (Forest Tent Caterpilar and Spruce budworm) at regular interval on the dynamic of the mixed-wood boreal forest in Canada?
• What are the impacts of interactions between disturbance types (insect outbreaks, gaps and fires) on structure and composition; this work will include the evaluation of changes in different disturbance regimes?
• What are the effects of a dense understory cover of shade tolerant competing species on the dynamic of the mixed-wood boreal forest in Canada?
• What is the role of high spatial variability in tree seedling recruitment (density and species) in maintaining tree species diversity over time in boreal mixed-wood forests?

Practical questions:

• What are the ecological and silvicultural implications of the multiple cohort approach suggested by Bergeron et al. 1999 for black spruce and mixed-wood forest of north-western Québec?
• Evaluate the ecological and silvicultural implications of various alternative silvicultural scenarios to naturally regenerate the boreal mixed-wood forest of Canada
• Link SORTIE to a landscape model (SELES) to help various forest industry to implement their sustainable forest management plan

Puerto Rico

Presented by Jill Thompson.

Site: Luquillo Mountains, Puerto Rico.

• Subtropical Wet Forest (Holdridge System) - dense understory, lots of light.
• LFDP in Tabonuco forest, below 600 asl
• 3,500 mm of rainfall/yr
• Major hurricane return interval is 60 years (and increasing?) Major hurricanes since 1932
  • Hugo September 1989
  • Georges September 1998
• Land-use data since mid-30's exists

Research questions: What are the implications of variation in hurricane frequency and severity for:

• The long-term dynamics of forest structure, composition, and diversity?
• Different time scales of recovery in temperate vs. tropical systems?

What are the relative importance of:

• The ability of tree species to resist and recover from damage to canopy trees by hurricanes?
• The species ability to exploit hurricane disturbances via new seedling colonization and sapling growth, for long-term patterns of tree species abundance and coexistence?

SORTIE: There are 5 submodels to study:

• Hurricane disturbance
• Light
• Recruitment
• Growth
• Mortality