WOODSHED ANALYSIS

Addison County Five Towns

Analysis by Marc Lapin, Chris Rodgers, & David

Brynn

Winter/Spring 2009

Purpose

To model the forest landbase suitable for sustainable harvest of forest biomass, and to estimate low-quality wood production on that landbase

General Methods

Determine forestland sustainability criterion that can be utilized for spatial modeling

Construct spatial model to evaluate the landscape

Calculate the low-quality wood growth on the suitable forest landbase by applying several forest growth estimates to the suitable acreage

Sustainability CriteriaApplicable to Spatial Modeling

Ecological criteria for sustainability refer to forest health, productive capacity, soil and water, biodiversity, and carbon and nutrient budgets

Soils Forestland Value Group

Exclude two least productive groups, representing limited & very limited forestry potential (available from NRCS soils surveys)

SlopeExclude slopes >60%

Separate slopes 30-60%, which may present sustainability/operability constraints

Water Quality and Wetlands Exclude water bodies and wetlands Exclude 75’ buffered area surrounding all water

and wetlands Fragile and ‘Significant’ Natural Communities

Exclude all lands above 2,500’ elevation No reliable spatial data for significant natural

communities, therefore exclude 10% of landbase to account for such features as well as for the forest access road network

Conserved Lands Exclude all lands where timber extraction is legally

prohibited Separate publically owned lands from privately

owned lands for information purposes Conserved lands GIS layer, GAP Protection Level

data utilized

Suitable Forestlands Results

60% forested 52% of forestlands suitable = 42,100 acres 84% of suitable landbase privately owned 9% forested landbase legally protected from

extraction

10% subtraction leaves 37,900 acres available

Excluded Lands by Criterion

Percentages include ‘overlap’ among criteria

Water, wetlands & their buffers – 8.5% Forestland value group – 36.6% Elevation – 5.4% Slopes >60% – 0.9% Potentially unsuitable slopes – 9%

BRISTOL Small amount of

suitable forest May be more

than shown on less sloping parts of Hogback

Most public land in wilderness protection

LINCOLN Large acreage of

suitable private forest landbase

Large amount suitable public lands

Few areas with 30-60% slopes

Very small percentage with conservation easements

MONKTON Some moderate-

sized patches of suitable forest

Perhaps more than shown on less sloping areas of Hogback

Very small percentage with conservation easements

NEW HAVEN

Mostly farmland with some large wetlands

Very little suitable forest

Small percentage with conservation easements

STARKSBORO Large acreage of

suitable forest Substantial

amount of 30-60% slopes

Small percentage with conservation easements

Large amount of suitable public lands

Tree Growth Per Year Leak et al. (1987) – Northern Hardwoods modeling

Intensively managed – 1.7 green tons per acre Unmanaged – 1.2 green tons per acre

Sherman (2007) – based on FIA plot data Addison County – 2.6 green tons per acre

Frieswyk and Widman (2000) – based FIA plot data 1.25 green tons per acre

Frank and Bjorkbom (1973) – Spruce-Fir modeling Best case scenario – 1.25 green tons per acre

Estimated Low-Quality Wood Amounts in green tons/year

Most conservative estimate = ~22,000 Lowest growth rate, low amount low-quality Very believable

Mid-range estimate = ~31,000 Middle growth rate, low amount low quality Perhaps, with more intensive management

High estimate = ~57,000 Highest growth rate, high amount low quality Not supported by recent data

Unanswered Questions How much of the available and future wood in

the woodshed is/will be low-quality wood whose ‘best’ use after harvest would be for burning?

What is the actual growth per year? The models show substantial variation Without intensive field data collection in a specific

woodshed, we don’t know how reliable the estimates are for any actual landscape

Where to Place Confidence?

Leak et al. model for unmanaged forests and recent FIA-based estimates coincide rather closely

Sherman growth estimates appear too high A whole lot depends on management intensity,

which depends on balancing numerous values, not merely maximizing biomass for burning

Landowner choices are, perhaps, the greatest unknown

What to Continue Questioning Can our forests provide us with large amounts of

biomass for energy while continuing to provide the other ecosystem functions and services we expect and hope for?

Will landowners opt for more intensive management to strive for greater forest biomass?

As management proceeds over many decades, centuries, how much will the proportion of the low-quality wood supply diminish?

A role for coppice management?

Thank you!&

Time for Questions