J. Rombke et al., Earthworm densities in central Amazonian primary and secondary forests anda polyculture forestry plantation, PEDOBIOLOG, 43(6), 1999, pp. 518-522
The species composition, abundance and biomass of earthworms were determine
d in two plots of a polyculture forestry plantation (POA, POC) and in plots
of nearby secondary (SEC) and primary (FLO) forest since 1997. In contrast
to recommendations in the literature, hand-sorting was not successful for
collecting the worms due to their individual size (2 cm to 110 cm in length
) and their inhomogeneous distribution. In a preliminary study it was confi
ned that formalin extraction in areas of 4 m2 is an easy and quick method t
o sample earthworms qualitatively and quantitatively.
After eight sampling dates in the period from July 1997 to March 1999 the f
ollowing results can be presented:
The number of species is not very high (approximately 8; mainly Glossoscole
cidae). One peregrine species (Pontoscolex corethrurus) was found in the po
lyculture plot and one other (Dichogaster bolaui, Octochaetidae) nearby.
The abundance of earthworms in the FLO plot is low in comparison to many ot
her tropical rain forest sites ton average 3.0 +/- 2.4 ind/m(2) compared to
68 +/- 32 ind/m(2)). On the other hand, the amount of biomass is within th
e normal range known from other rain forests ton average 15.3 +/- 10.4 g fr
esh weight m(-2) in comparison to 12.9 +/- 6.2 g fresh weight m-L?).
Number and biomass of earthworms on the other three plots are considerably
lower than on the FLO plot and also lower than reported from the literature
(based on very few studies).