Data/hora: 12/06/2024 10:42:40

Biblioteca(s): | Embrapa Florestas.
Data corrente: | 23/09/2008
Data da última atualização: | 23/09/2008
Autoria: | SNYDER, B. A.; CALLAHAM JUNIOR, M. A.; LOWE, C. N.; ROSTKOWSKI, S. C.; HENDRIX, P. F.
Título: | Interactions between the invasive earthworm Amynthas agrestis (Megascolecidae) and the North American millipede Sigmoria ainsliei (Xystodesmidae).
Ano de publicação: | 2008
Fonte/Imprenta: | In: INTERNATIONAL COLLOQUIUM ON SOIL ZOOLOGY, 15; INTERNATIONAL COLLOQUIUM ON APTERYGOTA, 12., 2008, Curitiba. Biodiversity, conservation and sustainabele management of soil animal: abstracts. Colombo: Embrapa Florestas. Editors: George Gardner Brown; Klaus Dieter Sautter; Renato Marques; Amarildo Pasini. 1 CD-ROM.
Idioma: | Inglês

Conteúdo:

The invasive exotic earthworm Amynthas agrestis has recently been documented invading
relatively undisturbed forests of the southern Appalachian Mountains of North America. This
epigeic earthworm has been observed to decrease the depth of organic soil horizons which are
vital to the maintenance of soil biodiversity in forested ecosystems. Field data suggests that
millipede richness and abundance are decreased in locations where A. agrestis has invaded.
To investigate the mechanisms behind these effects, earthworms (Amynthas agrestis,
Megascolecidae) and millipedes (Sigmoria ainsliei, Xystodesmidae) were placed into 1 L
microcosms constructed with 500 g soil and either L (15g L-horizon material), FH (15 g F- and
H-horizon material), or L/FH (7.5 g L and 7.5 g F and H material) litter treatments. Total microcosm
CO2 efflux was measured weekly and microcosms were destructively sampled and reconstructed
with the same fauna and litter treatment monthly for 8 months. At each destructive sampling
date, millipedes and earthworms were recovered, rinsed in tap water, and weighed to assess
biomass change and mortality. Also at each destructive sample date, soil, remaining litter, and
material processed by the fauna were collected and sub-samples were analyzed for total C and
N and mineral N (NO3 and NH4). Soil from pots that contained earthworm treatments were
passed through a 1mm sieve (wet-sieved) to assess cocoon production.
Millipede mortality was greatly hastened in treatments that did not contain FH-horizon material,
and millipedes died more quickly in all litter treatments when A. agrestis was present. Likewise,
earthworm mortality was more rapid in FH and L/FH treatments when millipedes were present,
but the opposite trend was observed in the L treatment. Earthworm biomass increased in FH
and L/FH treatments (until week 8) but decreased from the beginning of the experiment under
the L treatment. Many more A. agrestis cocoons were produced in pots treated with FH and L/
FH than in pots with L alone. Interestingly, there was almost no A. agrestis cocoon production
when Sigmoria ainsliei was present.
Preliminary results suggest that CO2 efflux was increased by earthworms in all litter treatments
and was increased by millipedes in the FH and L/FH litter treatments. When both fauna were
present, preliminary results suggested additive effects in the L and L/FH treatments, but nonadditive
effects in FH, possibly indicating a competitive interaction. Data from total C and N
and inorganic N analyses will also be presented and discussed.
Results from this pot study suggest that the invasive earthworm Amynthas agrestis may directly
compete with the millipede Sigmoria ainsliei for food resources, particularly the smaller particle
material in the FH horizons of the forest floor. On the other hand, it appears that the millipede
may offer some biotic resistance to the invasion as we observed diminished earthworm
reproductive capacity in the experimental units where earthworms and millipedes both were
present.

Categoria do assunto: | --
Registro original: | Embrapa Florestas (CNPF)
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