Mycorrhizae: a key interaction for conservation of two endangered Magnolias from Andean forests
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Serna González, Llinet Marcela | 2019
Background and aims – Magnolia species are highly endangered in neotropical forests where they are
highly endemic and often very rare. However, little is known about their nutritional and soil conditions in
natural forests. In this study, we focused on two endangered Magnolia species that cohabit in the Colombian
Andean cloud forests in order to identify their conservation and nutritional status. We hypothesize that these
species might exhibit mycorrhizal colonization that enhance nutrients uptake in poor and disturbed soils.
Methods – Individuals of Magnolia jardinensis and M. yarumalensis were assessed in 11 000 m2 of Andean
forests remnants from Jardín municipality (Antioquia, Colombia). Foliar and soil samples were analysed
in the lab. Through a Principal Component Analysis (PCA) we identified the relationship between soil
conditions and foliar nutrition. Root fragments and rhizosphere samples from seedlings and juveniles up
to 3 m tall were collected to verify mycorrhizal colonization and presence of other microorganisms. Adults
were excluded of the sampling due to the difficulties to differentiate their roots among the rest of the species
in the forest fragments.
Key results – The surveys show that the M. yarumalensis population has an inverted J-shaped diametric
distribution suggesting a potential recovering population while the smaller overall distribution of
M. jardinensis in all diametric categories suggests that this species is likely to become extinct. Both species
grow in acidic, infertile soils, although foliar nutrient concentrations did not correlate with soil-nutrient
availability. Such a discrepancy and the high colonization levels of mycorrhizae (60–70%) and dark septate
endophytes (40–45%), suggest that plant-microorganisms may facilitate nutrition and enhance survival of
Magnolia species in stressed environments. Other fungi and bacteria were also found in their rhizosphere,
but their role with respect to Magnolia species remains unclear.
Conclusions - Mycorrhizal colonization of endangered Magnolia species seems to play a key role to their
performance in natural disturbed Andean forests. Aspects related to soil and rhizosphere ecology should be
included in conservation projects for endangered and endemic plants.
Key words – Rhizosphere, Andean cloud forests, Magnolia jardinensis, Magnolia yarumalensis, soil
fertility, tree nutrition, conservation, mycorrhizae.
LEER
