Field Surveys in and near an Estuary
Main Concept
Vegetation in and near an estuary, measurement of water clarity, bottom sampling,
water column sampling, Observational skills, tree height estimation and use of tree
corer, identification of tree species using taxonomic keys, forestry survival line and
stocking survey assessments, identification of salt marsh plants, use of quadrats for
salt marsh plant population estimate.
Estuary Principle related to the lesson
Ongoing research and monitoring is needed to increase our understanding of estuaries
and to improve our ability to protect and sustain them.
Relevant State Science Standards
No established standards for high school Marine Biology and Ecology elective
science courses.
Materials and Equipment
Field taxonomic keys, Secchi disc, Eckmann dredge, Van Dorn sampler, blindfolds, 1
100 ft. tape measure, marking flags, tree corer, compass (es), survey plot tapes,
quadrats using PVC pipe.
Background Information
Working knowledge and use of tree and wildflower taxonomic keys (as well as
personal knowledge of area species), how to use a Secchi disc, Eckmann dredge and
Van Dorn sampler as well as what parameters they measure and their relationship to
biota, how to conduct forestry survival line and stocking survey assessments using
flags, compasses and survey plot tapes and how to identify salt marsh plants as well
as estimating their population (s) using the quadrat method.
Outline of the Lesson
The lesson plan involves a field trip to a wooded area bordering an estuary ( I chose
Mosely Woods in Newburyport, Ma). The following activities are incorporated into
the lesson plan:
Discovering vegetation changes as one proceeds from the woods to the shore of the
Merrimack River. These changes are pointed out by the instructor and students are
using taxonomic field guides to identify specific vegetation and tree species. Use of
Secchi disc,Eckmann dredge and Van Dorn sampler in a pond which outlets into the
Merrimack River.
Observational Skills Blindfold Exercise
Students pair off, one is blindfolded and led by his/her partner to a random tree within
a 50 yd. radius. The blindfolded student may use any sense but sight to get to know
his/her tree, then are led back to the central area where they began. If, after taking off
the blindfold, they can find and identify their tree, then they flag it. This process is
repeated for their partner. Correctly flagged trees are then cored, and annual
rings/seasonal changes are observed. A height estimation is taken using a very simple
but accurate method. Finally, using taxonomic keys (ex: Field Guide to Trees and
Shrubs by George a. Petrides) the effort is made to identify their tree to
species/common name. Students are shown how to conduct forestry survival line and
stocking survey assessments using flags, compasses and survey plot tapes. Survival
lines and stocking surveys are run the same way, only the former is the study of new
seedlings (to 1 ft. in height/1 yr. old) while the latter involves more mature trees. To
implement this, students may be taken outside on a regular school day. Eighty-eight
(88) feet are measured off and flagged beginning to end. Students walk the 88' three
times and count the number of paces. Hopefully it will be the same each time; if not
take most common. This is known as 1 chain and is a forestry measurement. Now,
back to the woods.... a compass reading is taken and you can have the student take
four plots, for example. Each time he/she reaches 88'(1 chain) the survey plot tape is
used. This can be constructed by using a metal tent peg or similar, and a known
length of rope or wire. The student places the pin in the ground and makes a complete
circle. The area of the circle can easily be calculated and a figure may be reached as
to trees/sq.ft. In forestry practice, 4.8 tree seedlings per 10' radius plot tape is
considered healthy "reprod". Considerably lower than that requires replanting the
area. This decision is only made after completing 20 plots in the same area.
This method is called "running a survival line". A stocking survey only differs in that
you are surveying mature trees for a possible silviculture or even logging operation.
These two activities give students experience in practical as well as theoretical
forestry, and can be used to survey salt marsh grasses and flowering plants as well.
Tips and Hints for other Teachers
•
This lesson plan, if you are running it alone, should be limited to a maximum of
25 students.
•
This lesson plan takes 3 hours to implement so a field trip is ideal. If not
possible, the plan includes seven activities, each of which can be accomplished in
one class or less.
•
Address students on clothing requirements especially relative to time of year.
•
All perform "tick checks".
•
Express to students to exercise care in "Blindfold Exercise".
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Sources of Information: Field Guide to Trees and Shrubs by George A. Petrides
Field Guide to Wildflowers by Peterson