poster66: Invasion of Amazonian landscapes by the earthworm Pontoscolex corethrurus (Glossoscolecidae)
1. Invasion of Amazonian landscapes by the earthworm
Pontoscolex corethrurus (Glossoscolecidae)
Marichal R1, Brown G G4, Praxedes C5, Tselouiko S1, Feijoo A6, Zuniga M C6, Ruiz D6, Carvajal A F6, Quintero A F6, Oswald J3, Decaens T,
Hurtado M P2, Grimaldi M1, Desjardins T1, Sarrazin M1 and Lavelle P1,2.
Methods:
Objectives: 1. Earthworm communities hand‐sorted by TSBF method: 5 points per farm *
Pontoscolex corethrurus is an invasive endogeic earthworm (Fig.1) 3x25 x 20 cm monoliths = 270 samples. Identification and classification into
which is progressively colonizing Amazonian landscapes. The aim of ecological categories: endogeic, anecic, epigeic species.
this study was to determine if the proliferation of this species is a 2. Land‐use determination: pastures, forests, fallows after crop, fallows after
result of (1) competitive displacement of native species or (2) pasture, plantation, crops.
exploitation of a new niche, created by disturbances.
3. Soil parameters measured at each point
Study sites: 4. Statistical methods: PCA on earthworm communities at points with
P.corethrurus and co‐inertia analysis with soil data.
Six areas with 9 sample farms in each, in two
contrasted regions of the Amazonian arc of
deforestation were investigated: three are in
Results:
Colombia, near Caqueta; three are in northern Brazil P.corethrurus occurred mostly in pastures and fallows
(state of Pará). % P.corethrurus was greater in pastures, fallows and plantations than in
forests (Fig. 3)
Fig.1.: Pontoscolex P.corethrurus density:
corethrurus, a • was associated with a low density of other species
parthenogenetic species
•showed a different pattern than other species in the PCA (Fig. 4) but no
with demographic
profile of the r type opposition.
(fecundity is 10 times •Co‐varied with pH and N soil content (co‐inertia, Fig.5).
that of native species)
d = 0.2 d=1
P.corethrurus
Axis 2 (25.0%) Fig. 4: PCAs performed on P.corethrurus
and other earthworm ecological
Brazil categories it sampled points in Brazil
Fig.2. Study sites and Colombia respectively.
(a) (c):Variables associated to the first
FAP
C Axis 1 (42.2%) two axes: P.corethrurus, other
epigeic P FAC
endogeic, epigeic, anecic species
anecic F
(a)
(a) other endogeic (b)
(b) densities in Brazil (a) and Colombia (c)
d=1
(b) (d):Ordination of the sampled points
epigeic species
P.corethrurus onto the plane defined by the first two
FAP axes in Brazil (b) and Colombia (d). P =
P Axis 1 (39.0%)
P.corethrurus (%) Pastures, FAP = Fallows after Pasture,
FAC = Fallows after Crop, C = Crops, Pl =
100 Plantations.
Colombia
80 First axis shows how native species tend
60 (c) other endogeic species (d) Axis 2 (33.6%)
to decrease with land use intensification
(crops and pastures opposed to fallows).
40
20
0
Axis 2:
Fallows Fallows 22.5%
Forests Plantations Pastures P.corethrurus
(12) after (16) after (86) epigeic species
crop pasture C30 Fig. 5: Co‐inertia analysis among densities of
Al sr pH
(10) (12) K N20 earthworms in ecological categories and soil
N10 parameters, in Colombian points where
Fig. 3. P.corethrurus (%) among land‐uses (points with P.corethrurus). In bracket CTCe C20 P.corethrurus occurred. (a) Projection of
Axis 1: Mg C10 earthworm categories on the first two co‐inertia
numbers indicate sampled points. 61.3%
TB P axes. (b) Soil parameters (bd = bulk density,
Ca N30
rp numbers indicate the depth (cm), rp = resistance to
bd2
NH4 Ve bd5 penetration, sr = sheer strength resistance, TB =
bd10 Total Bases, N10, N20, N30 = N content, numbers
other endogeic species indicate the depth (cm) respectively, C10, C20, C30
= C content, numbers indicate the depth (cm)
(a) (b) respectively). RV = 0.09, p‐value=0.021.
Acknowledgements:
This work was supported by the Amaz project of french Agence
Nationale de la Recherche (ANR); P. Lavelle was the coordinador.
Conclusions:
Pontoscolex corethrurus colonizes areas favors soils with neutral pH and relatively high N and C contents
of sites where forest has been burnt.
(1) Université Pierre et Marie Curie and IRD, UMR BIOEMCO 7618, Centre IRD Ile de France,32 rue Results of PCA analysis suggest that the decrease observed in other species densities is rather due to
Henri Varagnat, 93143 BONDY Cedex, France
their inability to survive in open land conditions than competitive exclusion by P. corethrurus.
(2) Centro Internacional de Agricultura Tropical (CIAT), Unidad Suelos, ap aereo 6713, Cali,
Colombia However, observations made in other countries (Fragoso and Lavelle, 1986; Lapied and Lavelle, 2003)
(3) Laboratory of Geography and Remote Sensing COSTEL, UMR CNRS LETG 6554, Université de suggest that once P. corethrurus has invaded a land, most native species do not come back even when
Rennes, France reforestation occurs.
(4) Embrapa Florestas, Estrada da Ribeira, Km. 111, C.P. 319, Colombo-PR 83411-000, Brasil
(5) Coordenação de Zoologia, Museu Paraense Emilio Goeldi, Av. Perimetral, nº 1901, CEP 66077-
530, Terra Firme, Belém, Para, Brasil
(6) Universidad Tecnológica de Pereira, Apartador Aéreo : 97, Pereira – Colombia