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National Park Service

U.S. Department of the Interior

Northeast Temperate Network

Resource Brief

Forest HealthCoarse Woody Debris & Snags

The Northeast Temperate Network (NETN) began monitoring orest

health in 2006. Since then, 260 permanent plots have been established.

In 2009, NETN scientists will nish installing plots and collecting

baseline data; resampling will begin in 2010, giving NETN scientists

an even clearer picture o orest health.

Temperate orests are made up o a complex, interconnected web

o plant species, wildlie, and abiotic cycles. Because it would be

impractical to measure the many components o orest ecosystems,

NETN scientists monitor and report on a ew key measures o orest

health, called metrics. For each metric, NETN scientists have

dened a range o conditions that might be present at network parks.Ecological integrity ranks are then assigned by comparing existing

conditions to those expected or a healthy orest. Conditions are

labeled Good when they all within an acceptable range o variation,

Caution i they warrant concern, and Signicant Concern i they

require management correction.

Coarse woody debris (i.e., dead trees and the remains o branches on

the orest foor) and snags (i.e., standing dead trees) are one indicator

o orest health. Forests in most NETN parks do not have enough

snags or coarse woody debris. The Vanderbilt Mansion NHS was

the exception, rating good or both these metrics. Acadia NP also

rated good or snag density. The Home o Eleanor Roosevelt NHSand the Home o Franklin D. Roosevelt NHS rated good or coarse

woody debris, but just missed the good rating or snags because the

percent o medium to large snags was too low.

Status and Trends

The three Roosevelt-Vanderbilt park units had a good rating or coarse woody debris volume. This ecological indicator is based onthe ratio o live tree volume to coarse woody debris volume measured in orest monitoring plots. Parks interested increasing coarsewoody debris could ell or pull over trees, leaving them on the orest oor where they will provide important structure and contributeto a healthy unctioning orest ecosystem.

E X P E R I E N C E Y O U R A M E R I C A April 2009

Continued

Significant Concern:< 5 med-lrg snags/ha

Caution:< 10% standing trees are snagsor < 10% med-lrg trees are snag

Good:10% standing trees are& 10% med-lrg trees a

VAMA*

ACADELRO/HOFR

MORRSAGA

MABIMIMASARAWEFA

Snag AbundanceEcological Integrity ofNortheast Temperate Network

Significant Concern:< 5% live tree volume

Caution:5-15% live treevolume

Good:> 15%live tree volume

ELRO/HOFR

VAMA

MIMAWEFA

ACAD

SARAMORR

SAGAMABI

Coarse Woody Debris VolumeEcological Integrity Ranksfor Northeast Temperate Network Parks

The Vanderbilt Mansion NHS was the only park unit with good snagdensity. This ecological integrity measure is based on the number and sizeo standing dead trees in monitoring plots. Most NETN park units containyounger orests which oten lack snags. Medium-large sized, low vigor treescan be girdled to increase snag densities in young orest stands.*NETN parks and their abbreviations are listed under Monitoring Program.

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E X P E R I E N C E Y O U R A M E R I C A

Importance

Snags and coarse woody debris are critical components o

temperate orest ecosystems. Naturally messy, temperate orest

systems are requently subject to disturbances like weather (e.g.,

wind and ice storms) and disease that can weaken trees or damage

old trees, creating standing and allen dead wood. Dead wood,

in the orm o snags and allen coarse woody debris, provides

habitat or many taxa: woodpeckers orage or insects in snags;

salamanders, small mammals, and invertebrates hide under allen

trees; and owls nest in snag cavities. As they decompose, snags

and coarse woody debris recycle energy and nutrients into orest

systems. Finally, dead woodboth standing and allenhelps

to stabilize soil and regulate water fow. Many park managementpractices, including silviculture and hazard tree removal, can

impact the quantity or quality o these eatures; however,

thoughtul land management can maintain or enhance snags and

coarse woody debris in park orests.

What do we want to understand?

1. What is the density o snags compared to live trees and how do

conditions compare to ecological integrity benchmarks?

2. What is the volume o coarse woody debris compared to

that o live trees and how do conditions compare to ecological

integrity benchmarks?

Monitoring Program

The NETN has developed a long-term orest monitoring protocol

to track a representative suite o site and vegetation measures in

an extensive network o randomly located permanent plots at ten

park units in the northeast. O these, only Acadia NP is sampled

every year; other parks are sampled every other year. At each site,

pieces o coarse woody debris (10 cm diameter and 1 m long)

were tallied along three line intercept transects per plot. Snags

were measured within each tree plot, and will be tracked through

time until they are no longer standing.

Parks included in this monitoring program are: Acadia National

Park (ACAD), Eleanor Roosevelt National Historic Site (ELRO),

Home o Franklin D. Roosevelt National Historic Site (HOFR),

Marsh-Billings-Rockeeller National Historical Park (MABI),

Minute Man National Historical Park (MIMA), Morristown

National Historical Park (MORR), Saint-Gaudens National

Historic Site (SAGA), Saratoga National Historical Park (SARA),

Vanderbilt Mansion National Historic Site (VAMA), and Weir

Farm National Historic Site (WEFA).

More InformationKate Miller Phone/Email

Lead Scientist/NETN Plant Ecologist 207-288-8736

kathryn_miller@nps.gov

Links

Northeast Temperate Network: www.science.nature.nps.gov/im/units/netn/

Monitoring & Evaluating the Ecological Integrity o Forest Ecosystems:

http://science.nature.nps.gov/im/units/NETN/Reports/Reports/Tierney_

etal_2009_Frontiers_Forest_Monitoring.pdf

Coarse woody debris is assessed using line intersect sampling. Three 15mtransects are established in each sample plot. Logs and other dead tree partslarger 10 cm in diameter and greater than 1 m long that intersect the tapeare counted; the type o tree (conier or deciduous), species (i identifable),and degree to which the material has decayed is also recorded (NPS photo).

A downed tree becomes an ecosystem o its own, supporting brightorange Basidiomycete "bracket" ungi and sot mosses. Coarse woodydebris provide habitat or wildlie, recycle nutrients and energy back into

the orest system, stabilize soil, and regulate water ow.

Density o snags and coarse woody debris is typically higher in older

orests because it takes time or trees to age, be damaged by weather or

disease, and all. Forested systems in most NETN parks are relatively

young, and may not reach desired density o late-successional coarse

woody debris and snags or some time. To create these conditions

in younger orest stands, trees can be cut or pulled over and let, and

larger trees o low vigor can be girdled and let standing.

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