A Comprehensive Study of the Taxonomy and Ecology of the Lumbricid Earthworm Genus Octodrilus from the Carpathians - Earthworm Ecology - page 124

TABLE 7.3
Characters of the Lumbricid Species in the Beech Forest from Padis (the
Apuseni Mountains) with Ecological Significance

Length
(mm)

Diameter
(mm)

Fresh Weight
(g)

Ecologic
Category Character Species Pigment

D. alpina Reddish 40Ï50 2Ï3 0.02Ï0.07 Epigeic

D. byblica Red 45Ï105 3Ï4 0.23Ï0.40 Epigeic

D. clujensis Red 60Ï120 4Ï5 1.05Ï2.43 Epi-endogeic

O. bihariensis Gray 126Ï240 4Ï5 4.80Ï9.05 Endogeic

O. frivaldszkyi Gray 200Ï460 8Ï15 19.00Ï36.60 Anecic

It should be noted that a biomass of 256 g/m 2 is the highest earthworm biomass recorded in

the Carpathians. For comparison, Table 7.4 shows the earthworm biomass recorded in two neigh-

boring forest sites investigated at the same time as the Padis beech forest. The yearly mean
earthworm biomass of the community with the giant O. frivaldszkyi exceeds by more than 30 times
that recorded for fir tree forests and by more than 20 times that for mixed beech-fir tree forests.
The earthworm densities and biomass of these other communities are typical for the Carpathians
(Pop 1987). This enormous earthworm biomass, at least for Carpathian forests, implies extremely
high earthworm activity in soil and, as discussed in the next section, accounts for the characteristics
of this soil.

THE ROLE OF GIANT OCTODRILUS SPECIES IN BUILDING UP
VERMIC (EARTHWORM-BASED) CHARACTERS IN
MOUNTAIN SOILS

The very large Octodrilus species imprint conspicuous vermic (i.e., earthworm-based) characters,
mainly in soils developed on limestone or dolomite but more rarely in neighboring acid soils. This
earthworm activity is so intense that soils developed on different parent materials and usually
classified into different classes have quite similar structures and chemical properties in the upper
horizons.
The term vermic (earthworm based), introduced into soil systematics by the American Seventh
Approximation Survey (1960), indicates soils processed intensively by soil invertebrates, especially
earthworms. According to the Romanian system of soil classification (1979), the vermic term
characterizes soils that exhibit coprolites (casts of earthworms or of other soil-inhabiting inverte-
brates) and earthworm burrows (sometimes filled by soil material) in more than 50% of the volume
of the A horizon and in more than 25% of the volume of the subsequent horizon. Using this
definition, the vermic character has been considered diagnostic of only a few soil types, such as
chernozems in the class of mollisols. The definition can be misleading because a normally developed
soil must be vermic, that is, developed by some participation of earthworms and other soil inver-
tebrates. Kubiena (1953), when defining mull humus, stated: ÑPractically all soil aggregates are
earthworm casts or residues of them.Ò His statement should be extended because traces of the
activity of soil invertebrates, especially earthworms, can be shown micromorphologically through-
out the entire profile of most soil types. Hence, in the opinion of Pop and Postolache (1987), the
term vermic should be used to indicate only visible, macromorphologically stable, and lasting
aggregates produced by soil invertebrates.
On this basis, we studied the morphology and chemical characteristics of soils inhabited by
the giant Octodrilus species, and the morphological and micromorphological features of a vermic