Agriculture Reference
In-Depth Information
roots at 71.6 % with significant mean differences among species ranging from <25 % to
100 %. In a
caatinga
(low and relatively dry) forest on an extremely nutrient-deficient
spodosol, all roots were infected. The mycorrhizas formed were largely AM.
There is some evidence that certain tree species specifically promote the formation
of root mats near their bases, as in the Guyanese tree species
Dicorynia guianensis
(Figure IV.22). In this situation, a significant proportion of roots that accumulated in the
mat appeared to belong to another tree species (
Eperua falcata
) that was growing a few
metres distant (Grandval unp. data, in Wardle and. Lavelle, 1997). Similar effects have
been observed by Griffiths
et al.
(1996) in coniferous forests in Oregon (USA); the
distribution of ectomycorrhizal mats (
i.e.,
dense accumulations of ectomycorrhizal roots)
had a clear spatial structure that could be related to the presence of a few species of
understory trees.
