Methods for Field Study


Method #1 (Line Intercept) Method #2 (Strip Intercept) Method #3 (Plot Sampling)


Method #1 ~ Line Intercept Transect

"Data are tabulated on the basis of plants lying on a straight line cutting across the community under study (Bibliography #1). While a survey may only examine plants, our goal was to identify all types of ground cover. (See headings on data collection form). For this study, we randomly selected our one hectare plot and established the center. Along the randomly selected compass heading, we laid out our 100 meter measuring tape, 50 meters off of center. The other half of our team performed the same operation perpendicular to the center of our tape. (See site layout). We reviewed our data collection sheet to insure that our data collection methods and identification were consistent. Then each team took readings at 1 meter intervals along their respective intercepts, resulting in 200 total data points.

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Method #2 ~ Strip Transect

"A strip census involves walking a line established through an area and recording individuals observed from that line (Bibliography #1). Employing the same transect described above, this method required that we take readings at 10 meter intervals. At the 10 meter interval, we laid a meter stick perpendicular to the transect. The meter stick intercepted the transect at the 50 centimeter mark allowing us to take 5 readings to the right and left of the center at each decimeter. By taking readings at 0, 10, 20, 30, 40, 60, 70, 80, 90, and 100 centimeters, one avoids duplication of the line intercept reading. This resulted in 200 total data points.

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Method #3 ~ Plot Sampling (Quadrat)

"In plot sampling, one takes a manageable area of known size and identifies, counts, and often measures all individuals within it (Bibliography #1). We randomly chose four plots to survey. (See site layout for locations of plots.) The predetermined size of each plot was 5 meters by 2 meters. In order to achieve 50 data points in each plot, we laid out a grid at 0.5 meter intervals. We established and staked the 4 corners of a plot, marking the perimeter with string. Using a meter stick, we staked and flagged each 0.5 meter along the perimeter. We then ran our string horizontally and vertically, creating a gird with data collection points at each intersection. This resulted in 50 data points per grid. Since there were 4 grids, this resulted in 200 total data points.

 

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