Plant Community Structure, Fire Disturbance, and Recovery in ...

Contributions to the Study of Biological Diversity Vol. 3
Waini Peninsula and during incidental field trips
farther inland in the Northwest were the only
source for 90 species in the list. Of those, 53,
approaching half of the Waini flora, were known
only from Waini Peninsula collections, and those
taxa are indicated in the list in Appendix 3.
To illustrate the relative composition of the
regional flora at varying scales, Table 2.3 ranks
the 20 most species-rich families for each of the
three areas: the Northwest District, all Guyana,
and the Waini Peninsula. The overall highest
ranking family among all sites was Fabaceae
(Papilionoid legumes), which ranked fourth in
all Guyana, second in the Northwest, and first
in the Waini flora. Nine families were shared in
the top 20 families among all three areas:
Fabaceae, Orchidaceae, Poaceae, Cyperaceae,
Mimosaceae, Araceae, Euphorbiaceae,
Asteraceae (Compositae) and Apocynaceae. Of
the top 20 families, 18 were shared between the
rankings of the Northwest District and all
Guyana, while 11 of the top 20 families were
shared between the Waini and all Guyana. The
Arecaceae (Palmae), which ranked 14 th in the
Northwest were 23 rd in the full Guyana rankings;
the Malpighiaceae, which were ranked 19 th in
the Northwest were 21 st in the Guyana rankings.
Table 2.4. Plant species collected on the Waini
peninsula not listed for Delta Amacuro. One variety
is also listed. Ten of these are primarily coastal,
indicated by *.
Amaranthaceae Alternanthera sessilis
Arecaceae Nypa fruticans *
Aristolochiaceae Aristolochia trilobata
Caricaceae Carica papaya
Combretaceae Conocarpus erectus *
Combretaceae Terminalia catappa *
Convolvulaceae Ipomoea violacea *
Cuscutaceae Cuscuta umbellata
Fabaceae-Caesal. Caesalpinia bonduc *
Fabaceae-Mimos. Entada polystachya
Fabaceae-Papil. Sesbania sericea *
Lygodiaceae Lygodium venustum
Malvaceae Thespesia populnea *
Myrtaceae Psidium guajava
Orchidaceae Epidendrum ciliare
Passifloraceae Passiflora foetida var. foetida
Poaceae Paspalum distichum
Poaceae Sporobolus virginicus *
Pteridaceae Acrostichum danaeifolium *
Rubiaceae Morinda citrifolia *
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Delta Amacuro
The Flora of the Venezuelan Guayana
(Steyermark et al. 1995 - 2005) listed 1649
species of pteridophytes and spermatophytes for
the state of Delta Amacuro. Among those species
193 (11.7%) were not listed for Guyana. Given
the proximity and environmental similarities, a
portion of those species might be expected to
be found in the Guyana’s Northwest District
with additional collecting effort.
Also, several species were collected on the
Waini Peninsula and in other parts of the
Northwest District that were not listed for Delta
Amacuro in the Flora of the Venezuelan
Guayana. Table 2.4 lists 19 plant species and
one variety that were collected in the Waini
Peninsula vicinity that were not recorded for
Delta Amacuro. In addition, the alga
Rhizoclonium africanum apparently had not
been documented for Delta Amacuro, although
it is almost surely present in the coastal
Avicennia swamps.
Appendix 4 lists plant species from the
Northwest District that were not yet recorded
from Delta Amacuro. Sources include records
from this study’s ancillary trips beyond the
Waini Peninsula site to interior localities near
Mabaruma and Kwebana (see Figure 2.1), as
well as from collection-based literature (van
Andel 2000b) and from specimens at the US
National Herbarium. That list includes 517
species of vascular plants from the Northwest,
without cultivated or naturalized species, more
than 31% of the 1649 species currently known
for that state.
Regional and Global Affinities
The strongest affinity of the Waini
Peninsula flora was with the Neotropical
distribution category including the Antilles
(zones 3 + 3a in Figure 2.3), which accounted
for approximately 33% of the Waini species. The
next strongest affinity was with the Pantropical
distribution category (zone 7), including
approximately 27% of the species. The
Neotropical - African, or transatlantic,
distribution (zone 4) comprised about 10% of
the species, including all mangrove and
mangrove-associate taxa, being those in the
genera Avicennia, Laguncularia, Rhizophora,
and Conocarpus. Notably, only 1.6% of the