PURPOSE: To measure certain elements of the physical environment in three distinct habitats. 

METHODS: For the three areas use an open field, a forested ridge top, and a forested ravine (preferably near a stream). Attempt to complete all measurements in as brief a time as possible. Environmental measurements are time-sensitive. In your report discuss the differences noted in these physical factors and the possible reasons for these differences. 

You will examine the following physical factors: 

Light. --Using a light meter record the light intensity in LUX when the meter is pointed toward the unobstructed sky and toward the ground. 

Wind Speed. –Using the anemometer (wind speed instrument) record wind speed at ground level and as far as you can reach above your head. Do not obstruct the flow of air with your body. In the event that the wind speed is insufficient to get a reading on this instrument, refer to the Beaufort Scale below and enter the value that most approximates wind speed. 

Relative humidity. --Using a sling psychrometer, measure the relative humidity as follows. Soak the cloth on the wet-bulb thermometer with distilled water. Then by whirling the psychrometer depress the temperature of the wet-bulb thermometer by evaporative cooling. When the temperature can be depressed no further (a minute or so), take a reading of both the wet-bulb and dry-bulb. Record these readings and use the sliding scale to determine relative humidity. 

Air Temperature. --The air temperature will be the same as dry bulb temperature on the psychrometer. Record this measurement as air temperature 

Soi1 Temperature: --Take soil surface temperatures by inserting the stainless steel dial thermometer tip one inch into the soil and waiting for the temperature to stabilize. Record a subsurface soil temperature at a depth of 4-5 inches by inserting the stainless steel dial thermometer into the soil to this depth. 

Soil pH: Use the soil pH tester following directions provided. Be certain to clean the metal plates on the sides of the cone with the dull surface of the green cleaning paper. Do not touch the surface of the plates with your fingers.

Soil Moisture Content (% Saturation): Use the soil pH tester to measure % Saturation by depressing the white button for a period of 1-3 minutes (no needle movement) and reading the value from the moisture scale. Clean the mud/dirt from the metal plates with a paper towel before placing the instrument back into its sheath.

Soil Compaction: Use the directions provided for the soil penetrometer to measure the degree of compaction of the soil at three locations at each site. Record the each of the instrument readings and calculate the mean.

Written report due at the beginning of next laboratory period to include the following 

1.  Description of each of the sampling areas. 

2.  Presentation of the data in the form of a table with the measurements arrayed vertically and the three sampling areas arrayed horizontally. 

3.  Your interpretation of the collected data in light of the potential effect that the measured physical and chemical factors might have on distributions of organisms or on their abundances. 

4.  A listing of any plant or animal species noted at the three sites whose distributions could be attributable to differences in measured physical/chemical factors. Are there species of plant that occur at one site that do not occur at another site? These could be important indicators of habitat. 

5.  An explanation of differences in recorded measurements.

Purpose: To determine microhabitat diversity and cover characteristics for three distinct terrestrial grassland habitats: (1) Kentucky 31®Fescue pasture, (2) cultivated warm season grass plot, (3) Plateau® herbicide warm season grass plot. 

Discussion: Macrohabitats are broad categories of habitat that are generally associated with broad spatial scales (Brower et al. 2a). Microhabitats occur on smaller spatial scales and are contained within macrohabitats. A species may be restricted to a particular macrohabitat but may occur within that macrohabitat only at specific locations where microhabitat conditions are suitable for its existence. Any evaluation of habitat is an evaluation of the suitability of a location for an animal or plant species population. 

Of the many components of animal habitat, vegetation is surely the most important for determining distributions of animal species. But animals do not all utilize vegetation in the same manner. Some animals are associated with and dependent on specific species of plants. An example of this would be the monarch butterfly and milkweed (Asclepias sp). Monarchs depend on milkweed not only as a food source for adults but as critical habitat for laying eggs and for development of larvae. Obviously any evaluation of habitat for monarch butterfly would need to include information on the availability and abundance of Asclepias sp. 

Other animals feed on and utilize a variety of different plant species. For these, the presence or absence of single species may not be as important as the presence of a diverse variety of plants. Still other animal species are essentially indifferent to the presence or absence specific plants because they use plants for hiding places and for nesting/resting sites, and either do not rely on plants as a food source or feed on a variety of plant items and exhibit little preference for particular species. Animals in the latter category utilize particular habitat as cover. Vegetative cover will diminish light intensity or obstruct vision, both horizontally and vertically. For the purpose of the following discussion, it will be assumed that either light intensity beneath the cover being measured or the obstruction of vision is a function of cover. 

Evaluation of Cover Density

Techniques for evaluation of cover density include: (1) ocular estimation, (2) counting the number of stems per sample guadrat, (3) measuring the obstruction of vision, (4) measuring, by photoelectric devices, the influence of cover on exclusion of light, and (5) photography. In this exercise we will use two of these methods (3 and 4) to assess and compare the cover density that occurs in three distinct grassland (macrohabitat) habitats at Clay Hill Memorial Forest. 

Much of the pasture land at Clay Hill was seeded with Kentucky 31® Fescue many years ago. Because this grass is unproductive for wildlife and because it is a non-native species we are trying to replace it with communities of native warm season grasses. Two fields were chosen for seeding with warm season grasses in 1998. One of the fields was treated with Plateau® herbicide and then seeded with grass seed from Hart County KY. This field was burned in March of 2001 and will be burned again in February 2002. The second field was plowed turning the fescue under and left idle for a month or two until it was cultivated and planted with the same seed using a seed drill in 1998. The second plot has not been burned but is scheduled for burning in February 2002. This plot was bush hogged in June of 2001. 

Measuring Obstruction to Vision

Wight (1938) proposed a quantitative technique of measuring cover by use of a "density board." The board is 6 feet in height with each foot marked off and numbered from 1 to 6. It is used in the following manner: The rod man places the density board in the cover to be measured and an observer reads the numbers that are not obscured by cover at a distance of one chain (66 feet). If there is no cover, the reading is 21 (1, 2, 3, 4, 5, and 6 added together); if cover obscures the entire board the reading would be 0. A series of readings--or the average of these data--would give some measure of the density of cover. The drawing below illustrates the use of the density board. 

Density Reading: 6, 5, and 1 are obscured and therefore not counted. Density would be 9; that is 4 + 3 + 2. To allow us to compare this density estimate with that derived photo-electrically, we will need to use these raw scores to calculate a proportion of total cover as follows:

Equation 1: % cover = (raw score)/(maximum possible score of 21)

This calculation yields a value that will hopefully be proportionate to that of % light penetration using the photoelectric method below

Measuring Cover Density by Photoelectric Equipment

Generally, specialized photoelectric equipment is necessary to measure density by this method. The Virginia Cooperative Wildlife Research Unit, however, devised a relatively simple method. Photoelectric readings of light conditions beneath various types of cover and in full light are made. The instrument used is a digital light meter with the light sensor supported on a frame 8-inches above an 8-inch square board, which has been covered with aluminum foil. The first light reading is taken with the photoelectric cell facing downward; therefore, the reading is obtained from light reflected from the base of the frame. A second reading is made quickly following the first with the light sensor placed above any of the blocking vegetation. Care should be taken to assure that no noticeable change in ambient light occurs between the time of the two measures and that the investigator does not shade the meter with any part of his/her body. The ratio below will yield a metric whose value will be directly proportionate to cover density. 

Equation 2: % of light admitted by cover=(reading of reflected light)/(reading of unobstructed ambient light)

Evaluation of habitat for any species must include knowledge of broad scale macrohabitat requirements of the species and macrohabitat of the site in question (Brower et al. 2a) as well as components of microhabitat that are important to the species being studied. The latter could include but would not be limited to (1) plant species diversity (2) physical characteristics of habitat (3) measures of habitat diversity. Habitat diversity (Brower et al. pp37-38) is a measure of difference within a habitat. This can be thought of as the topography or grain of the microhabitat. For example forests that have trees that are all equally sized in diameter and in height have habitat diversity that is lower than forests comprised of trees of many different diameters and heights. Streams that flow over solid slabrock generally support fewer fishes than those whose substrates are varied in size. Grasslands with grasses that always occur as single stems and that always reach relatively uniform heights are less diverse habitats than are grasslands with grasses of variable height and growth habit. In all of the above cases, variation in the grain of the habitat whether it be from changes in rock size or in changes in the growth habit of plants, increases the number of possible niches contained within the microhabitat. Habitat diversity begets both plant and animal species diversity. 

Here we will determine one component of habitat diversity (plant height) in two of the grassland habitats studied above, the Plateau ® herbicide warm season grass plot and the Kentucky 31® Fescue field. 

I have designed a device for measuring plant height diversity that will be used in this effort. The device is a 1 x 1 meter PVC pipe frame that is strung with a nylon thread to form a grid of 100 (10x10 cm) squares. The device is fitted with PVC legs such that the grid is positioned above the vegetation being analyzed. If the grass is too tall, the legs can be lengthened. Once the grid is in place, a meter stick is used to measure the distance from the grid string to the crown of the vegetation. This operation will require two persons, one measuring distances and the other recording the measurements on data sheets. For speed of measurement it is recommended that the measurements be rounded to the nearest cm. The drawing below is a representation the device and an old fat man using it. 
 
 

Sampling Methods

Establish three transects (50-meters in length) in each of the three habitats. Mark these with flags at the beginning and end and at 10 meter intervals between. Transects should be positioned such that they are 66 feet (22 paces) from one edge of the sampling area. This will facilitate coverboard measurements. 

At each flagged site record the following: 

(1) Coverboard raw score and calculated cover density. 
(2) Photoelectric light penetration. Record light meter readings reflected and ambient.

At the 30 meter mark (4^th flag) from the left in the herbicide field and in the fescue field, record raw data to calculate plant height diversity. This will require 100 measurements from each site. Record the measurements on the data sheets provided in the appropriate cell for a particular row and column. Each person should do some of the measuring. This will probably introduce error but we are not about being exact at this stage.

You should have five sets of data, one for each of three transects and two for the habitat diversity determinations. 

Cover density data (calculate for each transect and for each of the two methods used to estimate cover) 

(1)  Standard statistics to include mean, range, standard deviation, and standard error or the mean 
(2)  Use standard error to calculate confidence limits of the means (significance level of 0.05, at 5 degrees of freedom) 
(3)  Compare the mean cover estimates (photoelectric) using Student’s-t for the following: 

Herbicide verses Cultivation 
Herbicide verses Fescue 
Fescue verses Cultivation

Use the data to calculate several measures of plant height diversity (Brower et al. pp37-38). Instructor will provide computer program for entering and analyzing these data.

Prepare a table that presents raw data for cover estimates using both methods in each of the three transects.
Prepare a table that presents descriptive statistics for each of the three transects and two treatments. 
Prepare a table that presents the results testing the three hypotheses above. 

Ho1: mean cover estimate (photoelectric) did not differ in herbicide treated warmseason grass and fescue fields 
Ho2: mean cover did not differ in herbicide treated and cultivated warmseason grass fields 
Ho3: mean cover did not differ in clutivated warmseason grass and fescue fields

Prepare a table that compares habitat height diversity measures for each of the two sampled habitats.

Explain your results. Compare the two methods for cover estimation are they equally valid? Do they record the same or a different dimension of cover? Are the findings of cover in the three areas what you expected? Would these estimates differ had you recorded them during the summer?  Which of the thee sampled areas would you expect to have the greatest diversity of animals? Why?