Differential effects of tropical arbuscular mycorrhizal fungal inocula on root colonization and tree seedling growth: implications for tropical forest diversity
Et. Kiers et al., Differential effects of tropical arbuscular mycorrhizal fungal inocula on root colonization and tree seedling growth: implications for tropical forest diversity, ECOL LETT, 3(2), 2000, pp. 106-113
The potential for mycorrhizae to influence the diversity and structuring of
plant communities depends on whether their affinities and effects differ a
cross a suite of potential host species. In order to assess this potential
for a tropical forest community in Panama, we conducted three reciprocal in
oculation experiments using seedlings from six native tree species. Seeds w
ere germinated in sterile soil and then exposed to arbuscular mycorrhizal f
ungi in current association with naturally infected roots from adults of ei
ther the same or different species growing in intact forest. The tree speci
es represent a range of life histories, including early successional pionee
rs, a persistent understory species, and emergent species, typical of matur
e forest. Collectively, these experiments show: (i) the seedlings of small-
seeded pioneer species were more dependent on mycorrhizal inocula for initi
al survival and growth; (ii) although mycorrhizal fungi from all inocula we
re able to colonize the roots of all host species, the inoculum potential (
the infectivity of an inoculum of a given concentration) and root colonizat
ion varied depending on the identity of the host seedling and the source of
the inoculum; and (iii) different mycorrhizal fungal inocula also produced
differences in growth depending on the host species. These differences ind
icate that host-mycorrhizal fungal interactions in tropical forests are cha
racterized by greater complexity than has previously been demonstrated, and
suggest that tropical mycorrhizal fungal communities have the potential to
differentially influence seedling recruitment among host species and there
by affect community composition.