Envirothon Forestry Resource Guide Notes
Maryland's Forests
Maryland is described as “America in Miniature” due to its diverse land forms.
Forests range from Southern pine plantations on the Eastern Shore to hardwoods in the western mountains.
Maryland is ranked 42nd in land area.
It has 5 distinct physiographic provinces with diverse forests, wildlife, soils, and aquatic life.
The Chesapeake Bay is a major natural resource, part of a 64,000 square mile watershed.
Forests play a key role in protecting the Chesapeake Bay and supporting industries.
Overall Objectives for Students
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 resources and identify programs and strategies to mitigate them.
Specific Objectives for Students
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.
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.
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.
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 forestry tools, including diameter tape, Biltmore/tree scale stick, 10 factor wedge prism, increment borer/core, and clinometer.
Interpret forest data using tables and graphs including site index, volume, stocking, and rough cord volume.
Describe impacts of forest pests in 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 important for more complex measurements.
Learning Objectives
Understand why measurements are important in forestry and which tools are used.
Demonstrate proficiency in “pacing” to measure distances and determine paces in a chain.
Demonstrate proficiency in using forestry tools: diameter tape, Biltmore Stick/Merritt Hypsometer, clinometer, and 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
chains = 1 mile ( km)
square chains = 1 acre ( ha)
Several forestry tools are calibrated to be accurate at one chain.
Pacing
Pacing: counting steps to determine distance.
A compass helps determine direction, but pacing determines distance.
Distance measurements are based on a chain, which equals 66 feet ( meters).
To determine your pace, measure out 66 feet ( meters) 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 always measured on the uphill side of a tree at 4.5 feet ( meters) up the trunk, known as Diameter Breast Height (DBH).
Use a diameter tape (d-tape) to measure DBH.
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.
Tree Height
Tree height is measured using the principle of triangulation with a clinometer.
Use the clinometer at 1 chain ( feet or meters) away from the tree.
Aim the black crosshair of the clinometer level with the base of the tree at the soil to read a negative or positive number depending on the slope.
Aim the black crosshair of the clinometer to the top of the tree.
Add or subtract the numbers depending on eye level relative to the tree.
If eye level is between the base and top of the tree, add the numbers together to determine total height.
If eye level is below the level of the base of the tree (upslope), subtract the base reading from the top reading to determine total height.
Determining Logs or Sticks in a Tree
Trees are renewable resources used for many products.
To determine the volume of a tree, know how many logs or sticks are in the tree.
A log equals 16 feet ( m).
For sawtimber, logs are measured from the stump to an 8” ( cm) diameter top.
For pulpwood, measure the number of 8-foot ( m) sticks from the stump to a 4” ( cm) diameter top.
Use the Merritt Hypsometer, found on the Biltmore Stick, to measure logs and sticks.
Stand one chain away from the tree, hold the stick upright 25” ( cm) away from your eye with the Hypsometer side facing you.
Align the butt of the stick with the base of the tree and 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” ( cm) top or the first major defect in the tree.
For pulpwood, measure to a 4” ( cm) top, defects are less critical.
Determining Tree Volume
Once the diameter, height, and number of logs or sticks are known, the volume of the tree can be determined.
Volume is expressed in board feet, which is an imaginary chunk of wood 12” ( cm) X 12” X 1” ( cm) thick.
Use volume tables to compute volume quickly.
For eastern forests, use the International ¼ inch rule volume table.
Some Biltmore Sticks have volume tables on them; use the tree scale side of the stick.
Determining Tree Age
Counting growth rings determines tree age.
Growth ring spacing can indicate life events.
Tree age compared to diameter or height indicates site productivity or stocking.
Growth rings serve as a “history book” of the tree and its surrounding community, reflecting droughts, wet seasons, injuries, and fires.
On standing trees, age is determined by using an increment borer.
An increment core, a pencil-thin sample of wood, is extracted from the trunk, showing growth rings and ring spacing.
During the Envirothon competition, a sample increment core or the tree’s known age will usually be provided.
Determining Site Index
Site productivity depends on soils, climate, aspect, and other physiographic factors.
In North America, site index is the most common expression of site quality, based on tree growth patterns at a specific age (50 years for eastern forests).
Each tree species has its own site index.
Site index tables or curves exist for each major species of tree.
For example, if a dominant yellow poplar is 30 years old and 58 feet high, the site index is 70.
Determining Firewood Volume
Firewood volume is expressed in a cord, a stack of firewood measuring 4 feet ( m) wide X 4 feet high X 8 feet ( m) long.
Firewood is sold by the cord or half-cord in Maryland.
Foresters use a cord volume table to determine the firewood volume of standing trees.
Determining Basal Area
Basal area measures tree stocking on a site.
Basal area is the cross-sectional area of a 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, expressed in square feet per acre.
The formula for basal area is:
A wedge prism is used to determine basal area.
A 3.03 diopter prism is ground to an angle of 104.8 minutes, with a basal area factor of 10 (BAF = 10).
When using the wedge prism, hold it directly above the “plot center” stick.
If the offset portion viewed through the prism appears to connect with the main stem of the tree, tally the 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 borderline trees, tally every other tree.
Multiply the number of “in” trees by 10 to determine the basal area.
Determining Stocking Level
Stocking level is expressed in “trees per acre”.
Measure out 26 feet ( m) in each of the cardinal directions (north, south, east, and west) from the “plot center” to flag the circle boundaries, creating a 1/20th acre plot.
Count all of the trees within this circle that are greater than 2” ( cm).
Calculate the trees per acre by multiplying that number of trees by 20.
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 important for making forest management recommendations.
A chart is used to determine stocking level.
About Sample Points
Foresters often conduct measurements on the same sample point.
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.
Conducting sample points involves using compass reading, pacing, tree identification, and proficiency in using instruments.
Silviculture
Silviculture is both an art and a science.
It involves controlling the establishment, growth, composition, health, and quality of forests and woodlands to meet the needs of landowners and society.
It addresses the biological, ecological, and economic aspects of forests.
It is the practice of establishing, tending, and reproducing forest stands with desired characteristics.
Three themes stand out: trees, environment, and people.
Learning Objectives
Understand the definition and concept of a forest stand.
Recognize and identify crown classes in a forest stand.
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
Important 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: Manipulation of a young forest to ensure the desired stand composition, spacing, stem quality, and growth performance.
Regeneration Treatments: Removing the existing forest stand and planning for the reestablishment of the forest through natural or artificial regeneration.
Intermediate Treatments
Thinning: Redistributing growth potential to the “crop” trees in even-aged stands.
Crop Tree Release: Releasing selected crop trees in uneven-aged hardwood stands by felling or girdling competing trees.
Regeneration Treatments
Seed Tree Method: Leaving mature “seed” trees to repopulate the site.
Clearcut Method: Promoting regeneration of shade intolerant species by creating openings at least 1 acre in size.
Single Tree Selection Method: Removing single trees to maintain a self-sustaining forest of multiple age classes, favoring shade tolerant species.
About Crown Classes
Trees occupy different positions in the canopy and understory, referred to as crown classes.
Crown classes are:
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.
About Size Classes
Foresters classify trees into various size classes when conducting inventories of forest stands.
Size classes are:
< 2”
2”-5.9”
6”-11.9”
12”+
Tree Identification
Maryland has a great diversity of tree species.
Tree Identification Characteristics
Leaf shape – simple or compound, margins (edges), needles
Bark – smooth or scaly, peeling
Branching structure – alternate or opposite
Twigs and buds – stout or thin, clusters of buds or single buds