TABLE 1.
Numbers of organisms in the root zone in relation to plant species and soil depth (November)
| Microorganisms | Plant species | No. of subsamples analyzed
|
Mean no. of colonies/g (dry wt) of soil (SD)
|
||||
|---|---|---|---|---|---|---|---|
| 0-20 cm | 20-40 cm | 40-60 cm | 0-20 cma | 20-40 cm | 40-60 cm | ||
| PCB degraders (103) | Ash | 4 | 4 | 4 | 7.3 (5.2) Aab | 25.0 (27.0) Aa | 27.0 (43.0) ABa |
| Birch | 2 | 4 | 0 | 6.7 (0.01) Aa | 3.3 (2.0) Aa | NDc | |
| Black locust | 4 | 4 | 4 | 8.1 (5.2) Aa | 17.0 (15.0) Aa | 2.6 (1.0) ABa | |
| Pine | 2 | 4 | 0 | 8.0 (0.3) Aa | 68.0 (27.0) Bb | ND | |
| Willow | 6 | 4 | 5 | 2.2 (1.8) Aa | 1.3 (0.8) Aab | 120.0 (96.0) Ab | |
| Grass or no roots | 8 | 4 | 8 | 3.3 (3.5) Aa | 1.2 (1.2) Aa | 3.9 (4.9) Ba | |
| Total heterotrophs (106) | Ash | 4 | 4 | 4 | 5.7 (5.1) DEd | 17.0 (7.8) Dd | 8.9 (5.0) DEd |
| Birch | 2 | 4 | 0 | 1.4 (0.1) DEd | 4.1 (3.6) EFd | ND | |
| Black locust | 4 | 4 | 4 | 9.8 (6.2) DEd | 18.0 (1.6) De | 11.0 (2.7) Dde | |
| Pine | 2 | 4 | 0 | 12.0 (12.0) Dd | 14.0 (7.2) DFd | ND | |
| Willow | 6 | 4 | 5 | 3.0 (2.2) DEd | 2.5 (1.2) Ed | 5.4 (2.9) Ed | |
| Grass or no rootsd | 8 | 4 | 8 | 2.5 (1.9) Ed | 1.5 (0.4) Ede | 0.5 (0.2) Fe | |
a
Beneath all trees there were grass and forb roots at a depth of 0 to 20 cm.
b
Uppercase letters indicate significant differences in the same column, and lowercase letters indicate differences in the same row (P < 0.05, as determined by ANOVA).
c
ND, not determined because a sample was not available.
d
Grass roots were limited to the upper 0 to 20 cm of soil; hence, the soil obtained from 20 to 40 and 40 to 60 cm was considered non-root-containing control soil.