The purpose of this exercise on a typical Great Salt Lake Playa shoreline, will be to learn how to set up a transect in the field. A transect is a technique which ecologists use to investigate or describe a community. Students will be able to identify and measure the vegetation that exists in that transect. The transect technique or method is useful in that it provides a representative sample of the whole community by surveying a small section of a natural community.
group of 2-3 people)
-20 meters of string
-2 two-three foot metal rods or sticks which can be pounded into soil.
-2 meter sticks
-colored markers or pens
-assorted plant pictures (helpful if you have plant and animal book with pictures).
belt transect-a linear series of sampling points taken perpendicular to an environmental gradient.
community-a group of species.
key-an identificatin guide for playa plants.
gradient-change in our environmental factor.
zonation-distinct bands of vegetation.
salinity-amount of salt in soil or water.
TIME: Approximately 20-30 minutes of classroom time needed to explain procedures and close to 2 hours needed to gather data.
METHODS: (During the class time):
1) Inform students
that the field trip will be to the Great Salt Lake, where they will be
going to learn about the plant communities that are found there.
Also, let them know that they will be investigating plant communities through
a process called a belt transect.
2) Next, show the students how to use the belt transect.
3) Set up the transect, using a stake or rod at each end of a marked string. Explain that on the field trip the string will be tied to the rods pounded into the soil.
4) Draw a sample of the transect on the board and explain to students how to map the different communities of plants graph paper. They should label each block in the graph as 1^ meter and in each box students should put total # of each species found in that meter. HINT: Make an identification guide or instruction key to help you identify the plants . You can assign numbers to each plant. EXAMPLE: Pickleweed #1 Also, one can use different colors, symbols or letters to represent different species.
5) After students have devised an identification system, tell them that in each box on their graph, they will need to put the number of species in that meter next to the name or symbol they have assigned to that species.
(IN THE FIELD):
1) When you reach
the field site, give students few minutes to become familiarized with the
area. As you walk to designated field site, show students different
types of species and how to identify them. EXAMPLE: whether
of not plant is woody, size, shape of leaves and branching patterns, etc.
2) Students may gather a sample of each plant and label it with masking tape as they go along in order to help them better identify the species.
3) Next, students should divide into pre-arranged teams with one 20-meter line with 2 sticks, 2 meter stick, a set of colored markers or pens, graph paper and a clipboard. Review belt transect method and assign each group an area to set up their transect. Pound the rods or sticks in the ground in a straight line. Make sure string has been marked at each meter. Count or mark the # of meters on the string. In order to average the various team's data it is useful to place the 10 meter mark (the middle of the belt transect) at a similar standing point. In this case, the 10 meter mark was placed at the distinctive upper edge of the pickleweed vegetation boundry.
4) After setting up transects, students will record the number of species found inside each square meter and record that on their graph paper next to their symbols or name. It is helpful to place the 50 cm. mark on the meter sticks directly under the marked string. Plants can more easily be counted in each half meter. If an area has numerous individuals of a certain species, students can take small area of the meter (ie. 1/4) and multiply by 4.
5) Next, have the groups gather a sample of soil in a paper bag from the three 3 places along the transect (ie.at 0, 10 20 m) for future analysis of salt content, etc.
6) Give students a data sheet on which they can record their information and later summarize data.
Methodology for analyzing Soil Salinity
Soil salinity was determined
by using dried soil samples, re-hydrating a weighed amount of soil, and
then a YSI conductivity meter was used on the soil solution to determine
total salinity percentage.
*This exercise was tested by the fall 1999 general Ecology class at Westminster College in Salt Lake City.
RESULTS: The results below are a summary of average of individual transects conducted by class team members.
ABUNDANCE AND SALINITY (SUMMARY OF ALL TRANSECT DATA)
FIGURE 1.1 (Graphical representations of plant species density)
FIGURE 1.2 (Graphical representaitons of plant species Density)
BELT TRANSECT SPECIES DENSITIES (Presented as bar graphs)
GARDNER'S SALT BUSH
PLANT ABUNDANCE AND SALINITY (SUMMARY OF ALL TRANSECT DATA)
BELT TRANSECT SPECIES DENSITIES (#/M^2)
GARDNER'S SALT BUSH
The belt transect illustration given earlier shows the distribution of the major plant species and changing soil salinity. It is clear that different plant species of the Great Salt Lake Playa community are found in different zones along the belt transect. From analyzing dried, surface soil samples that were taken from the 0, 10, and 20 meter quadrats of the belt transect, it is clear that the distribution of the various plant species is affected by the amount of salt in the soil. For example, pickleweed occurs in greatest abundance where soil salinity ranges between 7% and 9.7% at the lower to middle part of the transect. Surprisingly, we found consistently higher sainities at the middle part of the transect, immediately below the annual grass zone (cheatgrass and mouse barley). This is probably due to evaporation around the margins of the water filled playa which concentrates the salt in the surface of the soil. The iodine bush is found within the pickleweed zone but is much more broadly distributed at higher elevations across the belt transect. However, the saltgrass zone begins where the annual grasses and weeds (Polygonum sp.; Hordeum murinum; and Festuca octaflora) appear and continues throughout the upper greasewood zone. The greasewood, driftwood and the gardner's salt bush are evenly distrbuted but an abundace of the species were recorded in quadrats 13 and 20, which may be due to the fact that the branches were counted as individual plants.