TOMÉ, M. P.; http://lattes.cnpq.br/5321856344613063; TOMÉ, Maysa Pereira.
Resumo:
The Brazilian Northeast is occupied by the Caatinga. a vegetation that has
adaptations that give it the ability to withstand droughts for long periods. The
herbaceous species present in this vegetation possess characteristics of
escape or tolerance to these conditions. However, this component has yet to be
analyzed, especially when it comes to studies that accompany its seasonal
transitions. Given this reality, the objective was to conduct a floristic and
phytosociological survey of the herbaceous component in an área of Caatinga
during the dry and rainy seasons. The study was conducted in the RPPN
Fazenda Almas, located between the municipalities of São José dos Cordeiros
and Sumé in the Paraiban Cariri region. A one hectare plot, subdivided into 100
subplots of 10m x 10m was established for the study. The floristic survey was
conducted over a year in al1 100 plots. All herbaceous species, including
"bryophytes and pteridophytes" were included. The phytosociological study was
carried out in the rainy season in March, and the dry month of July. Thirty-ave
subplots were randomly selected for the survey. The general flora (flora) had 27
families, 36 genera and 83 species. The most representative families were
Malvaceae (12) Convolvulaceae (lO), Euphorbiaceae (8), Leguminosae and
Asteraceae (6) and Poaceae (5). The phytosociological survey of the rainy
season yielded 4332 individuais belonging to 19 families, 41 genera and 50
species. The families with the highest number of species were Convolvulaceae
(8), Leguminosae (7). Malvaceae (6) and Euphorbiaceae (5). In the dry season
590 individuais were found belonging to 18 families, 30 genera and 38 species.
The families with the highest number of species were Leguminosae (5),
Asteraceae (4) and Poaceae (3). The taxonomic diversity in the rainy season
and dry season was 4,986 and 4,934, respectively. Of the 62 species found in
the phytosociological surveys (rainy and dry season), 22 were restricted to the
rainy season, 13 the dry season and 27 co-occurred in both periods analyzed.
Soil cover in the rainy season was 84.45%, while in the dry period was 32.23%.
Precipitation, brightness and competition are possibly responsible for the
change in the herbaceous component of the study área. However, even with
large differences in species richness, the results of the taxonomic diversity
showed no significant variation between the raíny and dry season. This shows
that this component, although ephemeral, has strategies to withstand water
stress conditions for long periods. This leads us to conclude that it is crucial to
understand the richness and dynamics of this component for us to estimate
accurately the diversity of Caatinga.