Percent Cover Evaluation

1) Use a 0-100% rating scale to assess the amount of bare ground and plant cover. Example: 20% of total plot area is bare ground, 80% of total plot area is covered with plants. Total should add up to 100 (e.g. 20% + 80% = 100%)

2) Of the area that is covered with plants, determine % covered with each species. Example: of the 80% of the area covered with plants in #1 above, you might have:

Ryegrass 30%
Alfalfa 40%
Fescue 30%
Total 100% (total should add up to 100%)

Following is a chart format to use in the field for the plant cover evaluations:

Evaluation Time: 6, 18, 30 months (circle one)

  % cover (Use 0-100% scale)
Bare Ground  
Plant Cover  
Total 100%

  % cover (Use 0-100% scale)
Common name   Scientific name  
Plant Species  
Species 1  
Species 2  
Species 3  
Species 4  
Species 5  
Species 6  
Species 7  
Total 100% (total should add up to 100%)

Shoot Biomass

Aboveground biomass production -- The amount of dry plant material produced in grams per meter squared.

Method: Sample three random 0.5 m by 0.5 m quadrats per plot. Clip vegetation within the area covered by the sample frame. Vegetation leaning outside the frame should not be included. Clip vegetation to level of 1-2 inches from the ground surface so crowns are not harmed. Dry vegetation should be put in paper bags, dried, and weighed.

Root Parameters

Method: Within each of the three quadrats selected for biomass production, sample one 2 inch diameter soil core to two depths of 0-6 inches and 6-18 inches. The diameter of the soil core can vary depending on sampling equipment but should be at least 2 inches in diameter. Record the volume of core samples for estimation of rooting density. Place each soil core in a labeled ziploc bag and cool to 4C. Transport to processing location.

For the purpose of this study it would be useful to send the root cores to a central location for processing to determine root biomass, root length density, and average root diameter. Roots will be separated from the soil and cleaned thoroughly. Cleaning involves a sequence of washing soil with water followed by separation of remaining debris from roots. To estimate root length density, clean roots are stained with methyl violet. Stained roots are spread on a clear surface to be scanned to obtain a digital image of the roots. Digital images are processed using software to estimate root length, root length density, root surface area, and root diameter. The volume of the soil cores is required for estimation of root length density. Following root scanning: roots are dried and weight to obtain an estimate of root biomass.

Plant hydrocarbon uptake analysis

At the end of the trial at the 30-month sampling all sites will analyze plant samples for hydrocarbon uptake. The protocol for analyzing the plant tissue will be similar to the soil analysis. Four composite samples of plant tissue will be analyzed for hydrocarbon uptake at the final sampling. From each vegetation treatment, there would be one aboveground shoot tissue sample and one belowground root tissue sample. To make the composite, collect some root and shoot material near the location of each final soil sampling location. Carefully separate and clean the root and shoot material putting together all samples from the sample vegetation treatment. The roots need to be washed carefully with water and detergent to remove all soil. Each of the four samples should be oven dried and thoroughly mixed so a representative100 gram sample can be sent for analysis to the contracting analytical laboratories. The root and shoot tissues should be analyzed for TPH and PAHs.

<< Back to Field Study Protocol