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Hardy and Heavy Metal-Tolerant Woodies for Contaminated Sites

Plant Materials Technical Note Number MT-42

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Plant Materials Technical Note Number MT-42 (PDF; 49 KB)

February 2002.

Introduction

Many areas in the Intermountain West have been impacted by hard rock mining activities. In western Montana, the Anaconda Smelter Superfund Site, situated in the Clark Fork River Basin, encompasses approximately 4,000 acres of sparsely vegetated land impacted by copper smelting and associated activities. At least one quarter of this land consists of steep upland terrain that cannot be accessed by heavy equipment. Revegetation of these areas, and perhaps other phytotoxic lands, with plant materials that have evolved tolerances to the existing soil toxins may be the most technically feasible and cost-effective reclamation approach.

A study testing the comparative performance of “local” versus “nonlocal” germplasm was installed near Anaconda, Montana, in the late fall of 2000. The “local” stock, originating in Deer Lodge County, Montana, was grown from seed collected at the Anaconda Smelter Superfund Site. The “nonlocal” stock used for comparison originated from a variety of counties within the western United States. The study compares 19 accessions of seven woody species.

Six- to 12-inch seedlings grown in 10-cubic-inch containers were transplanted into a common garden that had been plowed to a depth of 6 inches, rototilled, and then packed. Lab analyses of the four (0 to 6 in) composite soil samples taken after tilling indicated an average pH of 4.53 (Table 1). Arsenic and zinc levels exceed the Environmental Protection Agency (EPA) upper range values for phytotoxicity, whereas copper, cadmium, and lead exceed the lower range. The study was arranged in a randomized complete block design replicated 20 times. Plant entries were evaluated twice during the 2001 growing season for height, vigor, and survival. Height was measured in centimeters to the top of live foliage. Vigor was rated on a scale of 1 to 5 (1 = highest rating) based on visual assessment of plant health. Mortality was recorded when cambium tissue was no longer green.

Table 1. Acid Extractable Heavy Metal Levels and pH of (0-6 in) Composite Soil Samples.
Sample Number pH Arsenic mg/kg 1 Cadmium mg/kg Copper mg/kg Lead mg/kg Zinc mg/kg
1 4.00 610 7 620 320 370
2 4.90 360 5 340 120 222
3 4.60 530 5 340 150 200
4 4.60 190 7 740 340 440
Average 4.53 422.5 6 510 232.5 308
Phytotoxic Criteria 2 less than 5.00 136 to 315 5.1 to 20 236 to 750 94 to 250 196 to 240

1 mg/kg = milligrams per kilogram.
2 Phytotoxicity levels accepted by the EPA.

Results indicate that the best growth was demonstrated by Pinus ponderosa (Deer Lodge County, Montana) (4.75 centimeters) followed by Pinus ponderosa (San Juan County, Colorado) (3.02 centimeters) as shown in Table 2. The largest decrease in height was demonstrated by Shepherdia argentea (Sweetwater County, Wyoming) (-0.84 centimeters) due to die back and/or browsing. The most vigorous entry was Pinus ponderosa (Deer Lodge County, Montana) (1.95 centimeters) followed by Shepherdia argentea (Deer Lodge County, Montana) (2.11 centimeters). The least vigorous was Ribes cereum (Chaffee County, Colorado) (4.00 centimeters). Pinus ponderosa (Deer Lodge County, Montana), Pinus ponderosa (Lawrence County, Colorado), Pinus contorta (Deer Lodge County, Montana), and Symphoricarpos occidentalis (Weston County, Wyoming) had 100 percent survival. Symphoricarpos albus (Deer Lodge County, Montana), Symphoricarpos albus (Ravalli County, Montana), Shepherdia argentea (Deer Lodge County, Montana), Shepherdia argentea (Utah Seed Source), and Shepherdia argentea (Sweetwater County, Wyoming) had 95 percent survival. Mortality was greatest in Rosa woodsii (Ravalli County, Montana) (80 percent) and Rosa woodsii (Pueblo County, Colorado) (70 percent). Mortality over the entire plot averaged 15.8 percent.

Table 2. Origin, Growth, Vigor, and Survival Data from the Woody Comparative Evaluation Planting.
Accession Origin Elevation feet Growth centimeters Vigor 1 Survival percent
Pinus contorta Deer Lodge County, Montana 6,400 0.70 3.05 100
Pinus contorta Custer County, Idaho 6,300 0.53 3.16 95
Pinus contorta Albany County, Wyoming 9,500 0.59 3.20 70
Pinus ponderosa Deer Lodge County, Montana 5,850 4.75 1.95 100
Pinus ponderosa San Juan County, Colorado 8,000 3.02 3.00 90
Pinus ponderosa Lawrence County, South Dakota 5,500 2.55 2.35 100
Ribes cereum Deer Lodge County, Montana 5,700 0.88 3.06 80
Ribes cereum Chaffee County, Colorado 8,000 -0.49 4.00 65
Rosa woodsii Deer Lodge County, Montana 5,168 1.66 2.41 80
Rosa woodsii Pueblo County, Colorado 6,000 0.07 3.50 30
Rosa woodsii Ravalli County, Montana 3,400 0.50 3.50 20
Shepherdia argentea Sweetwater County, Wyoming 6,000 -0.84 3.32 95
Shepherdia argentea Deer Lodge County, Montana 6,000 1.44 2.11 95
Shepherdia argentea Utah Seed Source Unknown -0.31 3.26 95
Symphoricarpos albus Deer Lodge County, Montana 6,000 -0.63 2.21 95
Symphoricarpos albus Sweetwater County, Wyoming 6,000 -0.75 3.47 95
Symphoricarpos occidentalis Deer Lodge County, Montana 5,559 0.61 2.17 90
Symphoricarpos occidentalis Weston County, Wyoming 5,000 2.40 2.65 100
Symphoricarpos occidentalis Colorado Seed Source Unknown 1.00 2.89 95

1 Vigor rated on a scale from 1 to 5 (1 = highest rating).

Clearly the species best able to tolerate plot conditions were Pinus ponderosa, Symphoricarpos occidentalis, and Shepherdia argentea. “Local” accessions were superior to “nonlocal” accessions in six out of the seven species. Only Symphoricarpos occidentalis (Weston County, Wyoming) performed better than Deer Lodge County, Montana stock. The superior accessions within each of the seven species was Pinus contorta (Deer Lodge County, Montana), Pinus ponderosa (Deer Lodge County, Montana), Ribes cereum (Deer Lodge County, Montana), Rosa woodsii (Deer Lodge County, Montana), Shepherdia argentea (Deer Lodge County, Montana), Symphoricarpos albus (Deer Lodge County, Montana), and Symphoricarpos occidentalis (Weston County, Wyoming).

A woody component in revegetation mixes improves wildlife habitat by providing food, cover, and nesting opportunities. The establishment of trees and shrubs in combination with herbaceous plant materials will effectively stabilize slopes, thereby improving watershed health. Over the next couple of years, many of the superior performing accessions identified in this study will be released. Commercial production of the released germplasm by nurserymen and seed growers will ultimately increase the extent of plant materials available for disturbed land reclamation..

If you have any questions, please contact one of the following:

Joe Scianna, Horticulturist
Phone: (406) 662-3579
Email: Joe.Scianna

Jim Jacobs, Plant Materials Specialist
Phone: (406) 587-6995
Email: Jim.Jacobs

Ronald Nadwornick, State Resource Conservationist
Phone: (406) 587-6998
Email: Ron.Nadwornick

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Last Modified: 08/21/2008