Vegetation regeneration on the Reventador volcano calderain, the subandean mountain chain, north Ecuadorian Amazon

Abstract

In the caldera of Reventador volcano frequent eruptions
with lava flows have provided fertile ground for succession
studies in different landscapes and ages. A total of 25 plots, were
established. Plot sizes were 5x5m to study the low herbaceous
or shrubby vegetation, and 10x10m for tall shrubby vegetation.
A phytosociological method was used to assess vascular
(identification and coverage) and non-vascular vegetation. Twelve
endemic species belonging to nine families were identified, with
Bromeliaceae and Melastomataceae standing out. Four endemic
species are currently listed as Endangered, three as Vulnerable, two
of Minor Concern, one as Near Threatened, one as Not Assessed,
and one had Insufficient Data. The TWINSPAN program package
was used to characterize the different types of landscape units and
associations, defining two vegetation units, three sub-units and
seven associations, Unit I (2094-2391 masl), was composed of
three strata: herbaceous, shrubby low and high shrub, while Unit
II (2152-2213 masl), was mostly composed of pioneer species of
low strata with dominance of bryophytes and lichens. One hundred
twelve species of vascular plants were registered, belonging to
70 genera in 42 botanical families, with a range of plant cover of
80 to 100%. The species with the greatest relative diversity were:
Epidendrum (8 species, 7.27%), Elleanthus (5 species, 4.46%),
Blechnum (4 species, 3.57), and Elaphoglossum, Lycopodium,
Axinea and Psychotria with 3 species (2.69%) respectively. The
remarkable presence of 12 endemic species in the small space of
the old caldera of the Reventador volcano, can be explained by
it being surrounded by primary montane forest; which provides
resources for its repopulation, given niches that favor speciation.
The present study constitutes the first botanical description of the
plant succession in the caldera of the Reventador, providing the first
botanical data and new records for the country.