Data/hora: 23/05/2024 12:14:56

Biblioteca(s): 	Embrapa Florestas.	
Data corrente: 	22/09/2008	
Data da última atualização: 	22/09/2008	
Autoria: 	HEDDE, M.; BUREAU, F.; CECILLON, L.; DECAENS, T.	
Título: 	Effects of five earthworm species on soil structure and organic matter in LUVISOLs.	
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: 	Earthworms are frequently cited as key stone soil organisms, however, their effects on soil
structure stability and organic matter (OM) in macro-aggregates are mainly driven by soil type
and land use. Loamy soils of the Bassin Parisien are mainly dedicated to intensive crop which
have led to soil degradation. Introduction of pastures is one of the most promising practices that
may restore them. The aim of this work is to quantify and compare, in laboratory experiments,
the effects of 5 earthworm species on soil OM. We hypothesize that direction and magnitude of
earthworm effects depend on (i) earthworm species and (ii) OM of the substrate hosting it.
Five earthworm species were retained for the experiment (Aporrectodea caliginosa,
Aporrectodea rosea, Allolobophora chlorotica, Aporrectodea icterica and Aporrectodea longa).
The superficial soil of 3 stands were sampled in May 2006: a 30 yrs intensive crop stand (CS);
a 5 yrs pasture (YP); a 46 yrs permanent pasture (PP). Soil (150 g of 2mm-sieved) was added
to microcosms and moistened at field capacity at the onset of the experiment. Three replicates
were set up for each treatment (species x substrate) and stored for 3 weeks in climate chambers.
C-CO2 release during the experiment was estimated by the conductivity method (Heemsbergen
et al., 2004). At the end of the experiment, soil was air-dried and dry-sieved at 2 mm to isolate
and weight the large macro-aggregate fraction (> 2mm, LMA). LMA were characterized by (i)
their organic matter content (loss-in-ignition at 550 °C); (ii) their stability estimated by the more
desegregating test of Le Bissonnais? (1996) method and expressed as the mean weight diameter
(MWD) and (iii) their organic composition assessed by Near Infrared Spectroscopy (NIRS, Antaris
II Thermo electron).
The C-CO2 release may result from quality or localisation of soil OM. The high C-CO2 release
observed in CS-microcosms hosting earthworm can be explained by the mineralization of a
labile OM pool. This hypothesis was confirmed by the decrease of OM content in LMA. On the
other hand, in pasture soils, the lack of C-CO2 release increase in earthworm presence may be
due to a physical or chemical protection of OM.
Globally the rate of LMA production decreased with soil OM content increase. On low OM content
soil, earthworms should ingest a larger amount of soil than on high OM content soil to cover the
energetic needs.
Aggregate structural stability produced in earthworms hosting microcosms was lower (CS soil),
similar (YP soil) and higher (PP soil) than in animal-free controls. Although the factor ?species?
mattered, short-term stabilisation mechanisms in those loamy soils were firstly linked to the
initial soil OM content.
Interpretation of NIRS spectra showed that the regular disturbance regime YP was submitted to
might have maintained OM biochemical composition similar to CS one and that the composition
of soil OM influence the capacities of earthworms to modify this OM composition.
Biodiversity, Conservation and
Sustainable Management of Soil Animals
August 25 - 29, 2008
Positivo University
Curitiba - Paraná - Brazil
We demonstrated that earthworm short-term effects depend on both earthworm species and
initial soil OM. These effects are complex and appear mainly in the more contrasted soils.
Conversely, in the 5-years old pasture soil, earthworm presence has very few effects.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Florestas (CNPF)	
Exemplares: 	CNPF - (43665-1) - UPE - PL - -- - CD0305 -  -  - DIS