Envirothon Forestry Resource Guide

Maryland's Forests: An Overview

Maryland is described as "America in Miniature" due to its diverse land forms, ranging from the Atlantic Ocean to the Appalachian Mountains.
Forests in Maryland reflect this diversity, from Southern pine plantations on the Eastern Shore to high-quality hardwoods in the western mountains.
Maryland is ranked 42nd in land area among states but features 5 distinct physiographic provinces with diverse forests, wildlife, soils, and aquatic life.
The Chesapeake Bay, Maryland’s greatest natural resource, is part of a 64,000 square mile watershed covering parts of six states.
Maryland’s forests are crucial in restoring and protecting the health of the Chesapeake Bay while supporting vital forest product, agricultural, and seafood industries.

Overall Objectives

Understand and identify the five Physiographic Provinces of Maryland and the forest communities found there.
Understand the role of Maryland’s forests in restoring and protecting the Chesapeake Bay and its subwatersheds.
Perform accurate forest measurements and identify silvicultural practices.
Describe issues and threats facing Maryland’s forest resource and identify programs and strategies to mitigate them.

Specific Objectives

A. Physiographic Provinces and Forest Communities
- Identify the 5 physiographic provinces and describe the forest communities that make each one distinct.
- Identify common species of trees and shrubs native to Maryland.
- Describe the economic importance of sustainable forestry to specific regions of the state and identify key species and forest products.
- Describe the role of forests in restoring and protecting river and stream ecosystems.
B. Chesapeake Bay and Subwatersheds
- Identify the benefits of Riparian Forest Buffers and describe their importance in the Chesapeake Bay watershed.
- Prescribe forest buffer restoration techniques using topographic, soils, wildlife, and aquatics information.
- Describe the historical changes in forests in the Chesapeake Bay watershed and make comparisons to human and climate – caused changes in North American forests.
- Identify the states in the Chesapeake Bay watershed and recognize key legislation and cooperative agreements that use riparian forests to restore water quality and protect tributaries.
C. Forest Measurements and Silvicultural Practices
- Demonstrate proficiency in using forestry tools in the field to collect accurate stand data using a diameter tape, scale stick, clinometer, and wedge prism.
- Interpret forest data using graphs and tables including site index, volume, stocking chart, and rough cord volume.
- Identify silvicultural concepts and harvest techniques including stands, crown classes, thinning, crop tree release, seed tree, and selective harvest methods.
- Prescribe silvicultural techniques to enhance forest health, wildlife habitat, water quality, and economic growth.
D. Issues and Threats to Maryland’s Forests
- Identify significant forest pests and diseases found both in Maryland and North America. Describe their impacts to forest health, biodiversity, and economies.
- Identify factors contributing to the loss of the forest land base and describe efforts to reverse loss of forests, especially in urban areas.
- Describe strategies and programs used to combat specific forest pests and compare to efforts used throughout North America.
- Identify key invasive plant and tree species found in Maryland and describe their impact on biodiversity, forest health, and the economy.

Application/Analysis

Interpret maps and graphics to delineate physiographic provinces, land forms, and watersheds.
Identify common species of trees and shrubs native to Maryland using a dichotomous key.
Identify non-native/invasive species found in Maryland using a field guide.
Explain the importance of riparian buffers in protecting watersheds.
Collect and interpret forest data using the following forestry tools:
- Diameter tape
- Biltmore/tree scale stick
- 10 factor wedge prism
- Increment borer/core
- Clinometer
Interpret forest data using tables and graphs including site index, volume, stocking, and rough cord volume.
Describe impacts of forest pests Maryland and make comparisons to impacts throughout North America.
Identify and describe economic impacts of forest pests in Maryland and North America.

Measurements in Forestry

Forestry is a science based on measurements.
Proficiency with basic forest measurements is very important for more complex measurements.

Learning Objectives

Understand why measurements are important in forestry and understand which tools are used to obtain specific measurements.
Demonstrate proficiency in “pacing” to measure distances and determine how many paces you have in a chain (66 feet or 19.8 meters).
Demonstrate proficiency in the use of forestry tools:
- Diameter Tape
- Biltmore Stick/Merritt Hypsometer
- Clinometer
- Wedge Prism
Conduct a sample plot as part of a forest inventory using forestry instruments
Apply data to specific charts and tables to determine forest growth conditions.

Chain Facts

$80 chains = 1 mile (1.61km)$
$10 square chains = 1 acre (.4 ha)$
Several forestry tools are calibrated to be accurate at one chain.

Pacing

Pacing is counting steps to determine distance in the woods.
A compass helps determine direction, while pacing determines distance.
Distance measurements are based on a chain, which equals 66 feet (19.8 meters).
To determine your pace, measure out 66 feet (19.8 meters) using a 100-foot (30 meter) measuring tape, and count every other step.
Most people have between 12 and 15 paces per chain.

Tree Diameter

Tree diameter is an important measure of tree growth.
Diameter is measured on the uphill side of a tree at 4.5 feet (1.3 meters) up the trunk, known as Diameter Breast Height (DBH).
A diameter tape (d-tape) is used.
The d-tape is calibrated in “diameter equivalents of circumference by inches and tenths of inches”.
Diameter measurements should be expressed to the nearest tenth of an inch (e.g., 11.7” or 29.7 cm).

Tree Height

Tree height is measured using the principle of triangulation with a clinometer.
The clinometer requires practice and skill.
Steps for measuring tree height:
- Stand 1 chain (66 feet or 19.8 meters) away from the tree.
- Aim the black crosshair of the clinometer level with the base of the tree.
- Read a “negative” number if the tree is on level ground or down slope, and a “positive” number if the tree is up slope.
- Aim the black crosshair of the clinometer to the top of the tree.
- Add or subtract the numbers:
  - If your eye is at a level between the base of the tree and the top, the two numbers are added together to determine total height.
  - If your eye is below the level of the base of the tree (upslope from you), the base reading must be subtracted from the top reading to determine total height.

Determining the Number of Logs or Sticks in a Tree

Trees are renewable resources used for thousands of products.
To determine the volume of a tree, we must first know how many logs or sticks are in the tree.
A log is a unit of measurement equaling 16 feet (4.8 m).
For sawtimber, logs are measured from the stump of the tree to an 8” (17.9 cm) diameter top.
For pulpwood, we measure the number of 8-foot (2.4 m) sticks from the stump to a 4” (10.1 cm) diameter top.
The instrument used to measure logs and sticks is the Merritt Hypsometer, found on one side of the wooden Biltmore Stick.

Using the Merritt Hypsometer

Stand one chain away from the tree, hold the stick upright 25” (63.5 cm) away from your eye with the Hypsometer side of the stick facing you.
With the butt of the stick aligned with the base of the tree, count the number of 16-foot logs by matching the graduations on the stick to the trunk of the tree, until you reach an 8” (17.9 cm) top or the first major defect in the tree.
Measure to the nearest half-log (e.g., 1 ½ or 3 ½ logs).
For pulpwood, measure to a 4” (10.1 cm) top; defects are less critical.

Determining the Volume of a Tree

Once we know the diameter, height, and the number of logs or stick a tree contains, we can determine the volume of the tree.
Volume is expressed in board feet, which is an imaginary chunk of wood 12” (30.4 cm) X 12” X 1” (2.5 cm) thick.
Foresters use volume tables to quickly compute volume.
For eastern forests, the International ¼ inch rule volume table is used.

Determining Tree Age

Tree age is important for understanding growth conditions.
Growth rings serve as a “history book” of the tree and its surrounding community.
Droughts, wet seasons, injuries, and forest fires can be reflected in tree growth rings.
On standing trees, age is determined using an increment borer.
The increment core, a pencil-thin sample of wood, is extracted from the trunk, showing the tree’s growth rings and ring spacing.
Always bore on uphill side of tree.

Determining Site Index

The productivity of a site depends on soils, climate, aspect, and other physiographic factors.
Site index is the most common expression of site quality in North America, based on tree growth patterns at a specific age (50 years for eastern forests).
Each species of tree has its own site index.
Example: a 30-year-old dominant yellow poplar is 58 feet high, the site index is 70. By age 50, dominant yellow poplars grown in uncrowded conditions on that site could be expected to grow 70 feet high.

Determining the Firewood Volume of Standing Trees

The volume of firewood is expressed in a cord, a stack of firewood measuring 4 feet (1.2 m) wide X 4 feet high X 8 feet (2.4 m) long.
Firewood is sold by the cord, and in Maryland can only be sold by the cord or half-cord.
Foresters use a cord volume table to determine the firewood volume of standing trees.

Determining Basal Area

Basal area is a measurement of the cross-sectional area of a given tree stem expressed in square feet at DBH (4.5 feet or 1.3 m).
The basal area of a forest stand is the sum of the basal areas of individual trees, and is expressed in square feet per acre.
The formula is: $BA = .005454 X DIAMETER SQUARED$
A wedge prism is used to determine the basal area on a specific site or sample point.
A 3.03 diopter prism ground to an angle of 104.8 minutes is typically used, meaning that each tree tallied equals 10 square feet of basal area (BAF = 10).
The instrument must always be held directly above the “plot center” stick for accuracy.

Using the Wedge Prism

If the offset portion viewed through the prism appears to connect with the main stem of the tree, tally that tree as “in” or “countable”.
If the offset portion appears completely removed from the main stem of the tree, do not tally that tree as it is “out” or “not countable”.
For trees that appear to be “borderline” or on the edge, simply tally every other tree.
Multiply the number of “in” trees by 10 to determine your basal area.
Example: If you have 8 “in” trees, your basal area is 80, or you have “80 square feet of basal area per acre”.

Determining the Stocking Level

Stocking level is often expressed in “trees per acre”.
Measure out 26 feet (7.8 m) in each of the cardinal directions (north, south, east, and west) from the “plot center” to flag the circle boundaries, which equals 1/20th acre.
Count all of the trees within this circle that are greater than 2” (5.08 cm).
Calculate the trees per acre by multiplying that number of trees by 20.
Example: 13 trees within the circle multiplied by 20 indicates there are 260 trees per acre.

Determining Stocking Level Using a Table

Combine trees per acre data with the basal area of the site to determine whether the forest is understocked, fully stocked, or overstocked.
This information is used to make forest management recommendations.

About Sample Points

Foresters often conduct a stocking level measurement on the same sample point where they collect basal area information, site index, volume measurements, tree age, height, and species composition data.
This information, when combined with numerous other sample points, gives a clear, statistically accurate picture of the forest community being studied.
Sample points are designated based on a grid pattern.

Silviculture

Silviculture is the art and science of controlling the establishment, growth, composition, health, and quality of forests and woodlands to meet the diverse needs and values of landowners and society on a sustainable basis.
It addresses the biological, ecological, and economic aspects – both short and long term.
Three themes stand out: trees, environment, and people.

Learning Objectives

Understand the definition and concept of a forest stand as it relates to silvicultural practices.
Be able to recognize and identify crown classes in a forest stand.
Be able to identify and understand Intermediate harvest treatments and Regeneration harvest treatments.
Understand the important role Silviculture plays in producing a renewable and sustainable forest resource and conserving Maryland’s diverse forest ecosystems.
Be able to identify even-aged stands and un-even aged stands

Key Principles

Height growth of trees is generally a function of species and site.
Diameter growth of trees is a function of competition for water, sunlight, and nutrients.
Stand: A grouping of trees of sufficiently uniform species composition, age, and condition to be distinguished from surrounding stands and managed as a single unit.
Even-aged Stand: A stand of trees that is relatively the same age.
Uneven-aged Stand: A group of trees of a variety of ages and sizes growing together on a uniform site.

Silvicultural Techniques

Intermediate Treatments
Regeneration Treatments

Intermediate Treatments

Are any manipulation of a young forest to ensure the desired stand composition, spacing, stem quality, and growth performance might otherwise have been lost if the forest had been left to develop on its own.
- Thinning: A thinning is usually performed in even-aged stands with the primary goal of redistributing growth potential to the “crop” trees or to benefit the quality of the remaining stand.
- Crop Tree Release: Often prescribed in uneven-aged hardwood stands with trees that are 12” (30.4 cm) or more in diameter, the selected crop trees are “released” by felling or girdling those trees that compete with the crop tree.
  - Locate “crop trees” at a fairly uniform spacing throughout the stand.
  - 25 to 35 crop trees per acre (.4 hectares) should remain after releasing, this will space crop trees about 35 to 45 feet (10.5 m to 13.5 m) apart.
  - Remove trees on at least three sides of the crop tree.
  - Trees that are removed should be utilized for products such as pulpwood, firewood, or lumber.

Regeneration Treatments

Have the ultimate goal of removing the existing forest stand and planning for the reestablishment of the forest either through natural regeneration or artificial regeneration.
- Seed Tree Method: This technique removes all of the existing trees down to 2 inches (5.0 cm) in diameter, leaving mature “seed” trees to repopulate the site.
  - Generally 8-20 seed trees per acre (.4 hectares) are left after the harvest, and are usually of a single species.
  - Once a successful crop of trees has been regenerated on the site, the seed trees should be removed in a second harvest.
- Clearcut Method: The purpose of the clearcut harvesting method is to promote the regeneration of shade intolerant species by creating openings at least 1 acre (.4 hectares) in size by removing all trees down to two inches (5.0 cm).
  - Site preparation often follows a clearcut harvest to remove logging slash by prescribed burning, herbicide spraying, or using a bulldozer to push slash into windrows to create wildlife habitat.
  - If the Seed Tree method is not used, artificial regeneration may be used
- Single Tree Selection Method: Under this system, single trees are marked for removal. The goal of this method is to maintain a self-sustaining forest of multiple age classes.
  - Cutting a specific number of trees in each size class controls the structure of the forest, and the cutting pattern is repeated at regular intervals throughout the stand “rotation”.
  - This uneven age management system favors the reproduction of shade tolerant species.
  - In oak-dominated forest types, the uneven aged management system is generally not recommended.

About Crown Classes

Trees occupy different positions in the canopy and understory, referred to as crown classes.
- Dominant: Trees receive full sunlight from above and the sides.
- Co-dominant: Trees receive full sunlight from above and partial sunlight from the sides.
- Intermediate: Receive partial sunlight from above and sides.
- Suppressed: Trees receive only partial sunlight from above.
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About Size Classes

Foresters classify trees into various size classes when conducting inventories of forest stands.
When conducting a sample plot, the species, size class, site index, and volume is noted on a tally sheet.
This inventory process is often called cruising timber.
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Size classes used:
< 2” (< 5 cm)
2”-5.9” (5 cm–14.9cm)
6”-11.9” (15.2 cm-30.2 cm)
12”+ (30.5+ cm)

Tree Identification

Maryland has a great diversity of tree species due to its five distinct physiographic provinces.
During the competition, your team must identify 10 or 15 species of trees by their correct common name.
Use all of your senses (except hearing!) to examine the entire tree.

Characteristics to Look For

Leaf shape: Are they simple or compound? Are the margins smooth or toothed? Are the undersides of the leaves fuzzy? If the tree has needles, how many of them are in a bundle? Are the leaves scales like?
Bark: Is the bark smooth or scaly? Does the bark peel off or change texture further up the stem of the tree?
Branching structure: Are the tree’s branches alternate or opposite? (Remember in Maryland, only maple, ash, and dogwood are the most common opposite-branched tree)
Twigs and buds: Are the twigs stout or thin? Does the tree have clusters of buds or single buds? What do the bud scales look like?