Native earthworm species
diversity, biomass and abundance
in a wet eucalypt forest ecosystem (Warra LTER Site)
Susan Emmett • The Fenner School of Environment and Society • The Australian National University • CANBERRA, ACT 0200 • AUSTRALIA • [email protected]
Native Earthworms in Eucalypt Forests
Earthworm Sampling at the Warra LTER Site
The study was carried out at three coupes (WR001B,
WR008B and WR008C) located in the Warra LTER Site
Silvicultural Systems Trial (SST), and were sampled in 1997
and 1998.
This study forms part of a research project investigating the effects of
management disturbance on soil properties (chemical, physical and
biological) on native earthworm populations at three tall eucalypt sites in
southeastern Australia, including Bago/Maragle State Forest, NSW, Tanjil
Image: Mr Bill Brown (Forestry Tasmania)
Bren State Forest, Victoria, and the Warra LTER Site in Tasmania.
At the Warra LTER Site, the immediate effects of management
disturbance on earthworms are examined by pre- and post- disturbance
sampling of earthworms at three study coupes, located in a mixed old
growth forest dominated by Eucalyptus obliqua L’Herit.
This poster reports on pre- disturbance earthworm species diversity,
biomass and abundance, at the three study coupes in the Warra LTER Site.
Aporodrilus warrai (Sp. Nov.) (Blakemore 2000).
Length of specimen = approximately 15cm.
The coupes had not been exposed to management
disturbance including, clearfell, burn and sow (WR008B), and
dispersed retention of trees following harvesting at WR001B
and WR008C.
Earthworms were collected by digging a square pit of 50 cm
on a side and 45 cm depth, which was stratified into three
layers, each of 15 cm depth. Earthworms were separated
from the soil by hand and were killed in ethanol and later
sorted.
Pre- Disturbance Research Findings
EARTHWORM SPECIES DIVERSITY AND NUMBERS
EARTHWORM BIOMASS FOR EACH SAMPLE PLOT
WR001B
Depth (cm) 0-15
15-30
30-45
Megascolides sp.
WR008B
15
WR008C
Megascolides sp.
42
Aporodrilus sp.
7
Megascolides sp.
37
Megascolides sp.
18
Megascolides sp.
91
Megascolides sp.
48
Aporodrilus warrai
(Sp. Nov)
(Blakemore 2000)
23
Aporodrilus warrai
13
Aporodrilus warrai
29
Megascolides tener
(Sp. Nov)
(Blakemore 2000)
69
Megascolides tener
18
Megascolides tener
27
Aporodrilus sp.
138
Aporodrilus sp.
36
Aporodrilus sp.
45
Aporodrilus warrai
(Sp. Nov)
(Blakemore 2000)
25
Aporodrilus warrai
12
Aporodrilus warrai
19
Megascolides tener
(Sp. Nov)
(Blakemore 2000)
32
Megascolides tener
11
Megascolides tener
13
Aporodrilus sp.
82
Aporodrilus sp.
1
Aporodrilus sp.
15
Earthworm biomass (grams per [m]-2)
and to a depth of 45cm for each sample plot
12
10
Total biomass
89.90 g [m]-2
8
Total biomass
68.70 g [m]-2
6
Total biomass
66.15 g [m]-2
4
2
0
Total number identified
402
231
223
Unknown specimens
134
63
58
Study Coupe
• No exotic earthworms have been located to date.
• Five earthworm species of the Australian genera Megascolecinae are common to all three study coupes.
EARTHWORM ABUNDANCE IDENTIFIED
• Two species are surface dwelling and are generally located at depths of 0-15 cm in the soil profile.
For the three study coupes,
• The remaining three species include two previously undescribed species, Aporodrilus warrai (Sp. Nov)
(Blakemore 2000), (photo above) and Megascolides tener (Sp. Nov) (Blakemore 2000): both are deep
burrowing earthworms commonly found at depths of 15-30 cm and 30-45 cm, respectively.
• mature earthworms are commonly located in all three soil layers
(0-45 cm) (p<0.05).
• Cocoons of these deep burrowing species are also found at depths of 30-45 cm (photo below).
• Immature earthworms are commonly co-located with mature
earthworms and at depth of between 0-30cm (p<0.05).
• Earthworm species and numbers varied by depth and study coupe.
• Earthworm species diversity, biomass and abundance decreases
with increasing depth (p<0.05).
• When compared to the surrounding forest, there are no obvious edaphic variations in earthworm species
diversity.
FUTURE WORK
Research findings from post-disturbance sampling will describe
the relationships between
• earthworm species diversity, biomass and abundance
• soil microbial biomass
• soil chemical properties
Image: Mr Bill Brown (Forestry Tasmania)
• soil physical properties (including soil bulk density)
An immature earthworm emerging from a cocoon at the Warra SST Site.
Length of cocoon = 2.5 cm.
as a result of forest management at the three study coupes.
REFERENCES
ACKNOWLEDGEMENTS
Blakemore, R.J. (2000). Tasmanian Earthworms on CD-ROM VermEcology,
PO BOX 414, Kippax ACT 2615, Kippax ACT.
I gratefully acknowledge financial support from the Australian
Research Council (SPIRT)
Blakemore, R.J. (2000). The taxonomic status of the earthworm fauna
of Lake Pedder, Tasmanian Wilderness World Heritage Area – with the
description of three new genera and fourteen new species. Records of the
Queen Victoria Museum, 109.
and financial and technical support from Forestry Tasmania.