CORREIA, P.M., CARVALHO, L.M. & MARTINS-LOUÇÃO, M.A.
Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa. Campo Grande Bloco C2, Piso 4, 1700 Lisboa, POTUGAL.
In this work we used a nested sample scheme to assess the AM
spores distribution pattern and to evaluate in what way both abiotic and biotic
factors may influence it. We studied two Mediterranean ecosystems with different
edaphic conditions and plant communities: an evergreen sclerophyllous shrubland
(Serra da Arrábida) and a salt marsh community (Tagus estuary).
Core samples were collected every meter in a 5 x 5 m macrogrid,
every 20 cm within nested 1 x 1 m minigrids and every 5 cm within additionally
nested 20 x 20 cm microgrids. Plant cover and distances between core and plants
were recorded. Spore number and morphotypes were quantified in each core sample
as well as soil characteristics. Spores viability and germination were determined.
The results obtained so far showed that in both ecosystems
spores present a patchiness distribution. However the distance between patches
were different in each ecosystem. Spatial distribution in Serra da Arrábida
were correlated to organic matter and soil moisture, while at salt marsh ecosystem
they were only correlated with plant distance.
Spatial distribution of spores was expected, however our study emphasized the
importance of biotic and abiotic factors interfacing with plant rather than
plants species by its own on spatial patterns. Although temporal changes were
not yet evaluated, this study rouse attention for the relevance of these type
of ecological approaches particularly when we intend to understand the role
of AM symbiotic associations at ecosystem level.