Functional strategies of root hairs and arbuscular mycorrhizae in an evergreen tropical forest, Sierra del Rosario, Cuba

Abstract

The authors analyze here the excluding functioning of root hairs
and arbuscular mycorrhizae (AM) at the ecosytem level, showing that the socalled
exclusion of both structures depends on the biological types to be
considered for the analysis (trees, shrubs, vines, herbs and grasses). On the
other hand, exuberant and austere strategies have been defined recently to
explain the functional role of tropical forest tree successional groups and
ecosystems. As an approach to know how AM behave in that sense, six different
forest plots (three replicates each) were studied. Plots were different in showing
or not a mat of rootlets intermixed with a necromass matrix of raw humus over
the forest top soil (root mats). Firstly the replicates were analyzed separately for
plots with lower turnover rates (PLTR) or with higher turnover rates (PHTR),
showing that AM external mycelium is largely influenced by soil raw humus
contents. In a second analysis, plots were used as replicates belonging to two
treatments (PLTR and PHTR) in order to discover the major tendencies of AM
functioning. All the rootlet and AM variables associated to nutrient uptake
(rootlet phytomass, external mycelium, etc.) produced significantly higher values
in PLTR, while the value obtained for AM colonization was significantly higher
in PHTR. The exuberant and austere tendencies of AM functioning are explained
according to the obtained results.