Forest Survey

Forest Survey: Deciduous Forest near Lake Maury

AP ENVS  

Introduction:  

            Characterizing a community is one of the ways that collecting empirical data about an ecosystem can be used.  There are many possible influences on the ecosystem that results in the community observed at the time of the field investigation.  Stress, disturbance, succession, migration, lumbering, and landscaping could contribute to the composition of the community.  Biological zones, climate, soils, geology, elevation, and hydrology are some of the factors that can result in specific types of natural forest communities. 
            Sampling methods are means by which a community can be characterized without measuring and counting every member in a plant community in an ecosystem.  Classificaiton by referencing the dominant tree species is a way to describe a community.  Sampling methods should provide sufficient data to establish an accurate assessment of a plant community within a reasonable amount of time and with a reasonable amount of effort.
            We will be using a plot or quadrat method.  This method is somewhat time consuming compared to plotless methods, however it can be argued that this method is less likely to over  estimate a population or it’s density.  Rectangular plots, versus quadrats which implies four equal length sides, yield better results for sampling plants in forested areas.  Although most forestry studies are in English measurements, we will be reporting our data in metric measurements in keeping with globalization of information exchange.  

Method:        

LEAVES OF THREE, LET THEM BE.  IF THE PLANT HAS 3 LEAFLETS DO NOT TOUCH IT, PICK IT, OR SMELL IT.   THIS PLANT MAY APPEAR AS A VINE, AS A FREE STANDING PLANT, SCRAGGLY OR VERDANT.  It is Rhus radicans, POISON IVY.  Do not touch it with your measuring tape or anything else.  If you happen to walk through it or it touches your pant leg or sleeve, remove your clothing by turning it inside out and take it home.  Put it directly into the washing machine and run as instructed by your parent.  If you know you have touched it, see me immediately.  We will try to get the oil off.  When you get to school, wash the area with soap and water.  NEVER put your hands to your eyes if it can be avoided while working in the field.    

WALK WITH CARE IN THE LEAF LITTER.  Avoid stepping on animals or sneaking up on them.  It’s their home, not yours.  Do not make any animal, vertebrates especially, but also some invertebrates, uncomfortable in its home.  They could make you uncomfortable before you can get home. 

1) Each group will set up a plot which will be approximately 100m².  The transect lines are marked off in 3m intervals.  You will estimate 7m width by 15 m length.  The hypotenuse of your rectangle is 17m.  Rectangles have a tendency to become polygons without checking the hypotenuse.  Mark off your area using flagging material.   

2) One person should be the recorder.  Record abiotic data.  Then draw a large, rough map of the quadrat.  Use data sheets to record information about the plants present.   

3) After the plot is laid out, take abiotic data. 

Record weather, temperature of the air, temperature of the soil at 1 cm, temperature of the soil at 5 cm if the soil/leaf litter is loose and the thermometer is not in danger of snapping off.  If a thermometer breaks, carefully place all pieces back into the pvc tube.  If you are cut, see me immediately.   

4) As each tree is measured, put it on map as a number.  Use that number in the data sheet to record its circumference which will be converted to diameter at breast height (DBH) in inches.  We will convert numbers to cm in a spreadsheet. 

If the circumference measures < 24 cm it is considered to be a sapling.   

5) One person needs to collect and label a leaf from the tree/sapling/shrub being  identified.  If the leaf is compound – multiple leaflets form a single leaf, collect the entire set of leaflets.  Intact leaves are easier to identify than partial leaves.  Use a sharpie to label leaf.  Label it with the number assigned the tree or shrub.  Place in bag.  Attempt to give brief description of bark or arrangement of leaves to recorder-eg. Bark grey and deeply grooved, leaves compound and alternate.   

6) The other person/persons in the group need to methodically measure all the trees at breast height, 1 m from the ground.  If the tree is on a slope, measure on the HIGH side of the tree.

If there are multiple trunks, note that and measure both and we’ll add them together later.  

7) At some point, be sure to collect a quarter meter squared of leaf litter and the loose debris beneath it.  Bag the leaf litter in the large white garbage bag.  Use a trowel and shovel the loose detritus into a gallon size Ziploc bag.  Place in the same bag as the leaf litter.  Label with group name and your location (flat, on a hill, near water, …).  Separate from your quarter meter site, take a small sample of soil and place in small ziploc bag.  Place this in the large garbage bag with the leaf litter and the layer of humus.   

8) Although we will not have much time, everyone should look for animals or signs of animals where they are working.  Turn over logs, if loose, and look for insects and salamanders.  Replace log as you found it.  DO NOT REACH INTO LOGS OR HOLES.  It is too warm to look for snakes without proper equipment.  They are unlikely to be happy to see you and may demonstrate just how much they do not wish to be disturbed.  Even nonpoisonous snakes can and do bite, and you could get a serious infection from the bite.   

9) EVERYONE needs to record observations.  Odors, textures, and things you have seen need to be recorded.  Please do not write about the weather.  The abiotic data has already been taken.  I will check your notebook and sign off in it on the bus on the way home.   

10) BEFORE YOU LEAVE YOUR PLOT, make sure you have collected every piece of equipment, including the flagging, and have left the area as close to the undisturbed condition in which you found it.   

11) Back in class:

We will be setting up spreadsheets to help with the following calculations.  

Radius:  circumference cm / 2 / pi = radius in cm  

Basal Area covered: pi * r²  = area in cm²

Total number of trees sampled in 100 m² = sum of all trees w circumference>19”

One hectare = 10,000 m²  = 2.47 acres

Trees per Hectare:  total number of trees/100 m2 * 10,000 = trees/hectare

Mean Basal Area:  S(basal areas)/ total number of trees

Total Basal Area per Hectare:  Mean Basal Area * trees per hectare   OR

                                                   S(basal areas) /100 m2 * 10,000 = area per hectare  

Relative Density: Divide the number of individuals of a species by the number of individuals of all species. Multiply by 100 to get percent.  This value represents how often this species occurs in the community.

Density:  Multiply the relative density (divided by 100) times trees per hectare to calculate the number of trees of this species per hectare.

Relative Dominance:  Divide the total basal area of a species by the total basal area of all species.  Multiply by 100 to get percent.  This value represents the proportion of total basal area attributable to a species.

Dominance:  Multiply the Relative Dominance (divided by 100) of a species time the Total Basal Area per hectare to get the basal area per hectare for that species.

Frequency:  For each species, determine the number of trees and saplings.  Divide this number by the total number of saplings and trees.  Multiply by 100 to get percent.

Relative Frequency:  For each species, divide the frequency by the sum of all frequency values for all species.  Multiply by 100 to get percent.  This value represents how frequently this species occurs in comparison to other species.

Importance Value:  This value is the sum index for each tree species calculated by adding the Relative Density + Relative Dominance + Relative Frequency.  The sum of all Importance Values for a community adds to a constant value of 300.  The magnitude of the Importance Value is an indication of the vegetational importance of a species within a community.  This value is weighted toward density, in that the number of trees present exerts a greater effect on the index than does their size.  Importance value provides an overall estimate or the influence or importance of a species in a community.

Results:

Present your findings in a summary chart or a series of summary charts as you see necessary to communicate your data.  Do not forget that you must write a word picture of the data-call the reader’s attention to the points you consider most important.  Explain what these findings indicate. 

Points to consider:

What are the 3 species that occur most?
What are the 3 species that occur least?
Which species appears to have the most vegetational importance in the community?
Which has the least importance?
Are there any species with similar importance values?
For the species which has the largest importance value, which calculated factor has the most influence (or weight) on this value?
Is there a relationship between relative density and relative frequency of the trees in this forest community?
What types of abiotic factors (not just temperature and weather-consider others and look up rainfall for this area on the weather site) might have an influence on the forest community’s tree species distribution?
If a natural disaster such as a fire occurred in this forest, which tree species would you expect to see repopulate the forest?  Do you think this community will contain similar or different relative frequencies 40 years after the disaster compared to the data we collected?
What are the salient issues in the management of this forest?   
 

Conclusions:  Yours!  How would you characterize this community?

Status of Plants from National List of Plants found in Wetlands

Acer rubrum   FACW
Carya glabra   FACU
Cornus florida FACU
Liquidambar styraciflua FACW
Liriodendron tulipfera FACU
Persea borbonia FACW
Pinus taeda  FAC
Prunus serotina FACU
Quercus falcata FACU
Quercus lyrata OBL