Data/hora: 08/06/2024 11:59:33

Biblioteca(s): | Embrapa Florestas.
Data corrente: | 22/09/2008
Data da última atualização: | 22/09/2008
Autoria: | HEDDE, M.; BUREAU, F.; CHAUVAT, M.; DECAENS, T.
Título: | Mechanisms responsible for diversity-leaf degradation relationship within litter invertebrate experimental assemblages.
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:

Despite the great interest concerning the relationship between species diversity and ecosystem
functioning, there low knowledge as to how the diversity of detritivore macro-invertebrate
influences the decomposition of soil organic matter. The aim of this paper was twofold. First,
what is the more relevant measure of diversity to estimate species assemblage effect on a
given function? Second, what are the mechanisms underlying the observed BD-EF patterns?
To answer these questions, we explored the relationship between small experimental
communities of litter macro-detritivore invertebrates and selected indicators of organic matter
degradation.
Four detritivore macro-invertebrate species were selected: a woodlouse (Oniscus asellus), an
earthworm (Dendrodrilus rubidus) and two millipedes (Glomeris marginata and Cylindroiulus
latestriatus). All mixtures from one to four species were made (3 replicates). Invertebrates were
added to microcosms with partially decayed beech leaves. Microcosms were stored for 3 weeks
in climate chambers. Performances on leaf mass loss and C-CO2 release were measured.
Assemblage diversity was measured through (i) species richness (SR), (ii) morphological
dissimilarity (MD) and (iii) functional dissimilarity (FD). Dissimilarities were assessed by
Euclidean distances between species trait coordinates in a multivariate space. Morphological
traits were chosen among morphological attributes related to resource foraging and litter
fragmentation. Functional traits were linked to leaf degradation abilities. The calculation of net
diversity effects and transgressive overyielding allowed discriminating between negative, neutral
and positive interspecific interactions responsible for observed patterns.
Performances of macro-invertebrate assemblages on beech leaf degradation process appeared
to be related to FD rather than to MD or SR. While it has been documented for plant productivity,
only one experiment showed it for soil process. We can advocate that functional equivalence
within mixture of species belonging to a same trophic group limits its performance on leaf
degradation processes. Saturation in process rates occurred after more than SR was greater
than one species which should have reinforced the idea that a significant impact of soil organisms
occurred on decomposition and nutrient cycling at low level of SR, leading to misunderstanding
of BD-EF relationship. Performances of species mixtures were due to negative, neutral or positive
interspecific relationships. Species complementarity explained both leaf mass loss and C
mineralisation performances of D. rubidus-O. asellus and C. latestriatus-O. asellus mixtures.
We can argue that this complementarity was likely to be related to facilitation rather than to
niche differentiation since substrate heterogeneity has been minimized in our experimental
design. Conversely, performances of C. latestriatus-D. rubidus associations were due to neutral
interspecific relationships. This may reveal that these two species fed on different part of decaying
leaves without interactions. Underlying mechanisms of performances for all other mixtures differed
between leaf degradation indicators (leaf mass loss and C-CO2 release). This is consistent
Biodiversity, Conservation and
Sustainable Management of Soil Animals
August 25 - 29, 2008
Positivo University
Curitiba - Paraná - Brazil
with the idea that mechanisms of species performance may differ, for a given mixture, according
to process.
In our work, we used statistics to measure the degree of species dissimilarity instead of grouping
species a priori based on similarity in morphology, life-history, and/or function. Exploring the
BD-EF relationships is related to the question whether equivalence exists between species
performances. This idea is specifically embodied in the concept of ?functional groups?. Our work
and that of others suggests that when we simplify the world by ignoring species identities, that
cost is often too great.

Categoria do assunto: | --
Registro original: | Embrapa Florestas (CNPF)
Exemplares: | CNPF - (43664-1) - UPE - PL - -- - CD0305 -  -  - DIS