SILVA, J. C.; SILVA, Jardel Costa.
Résumé:
The objective of this research was to evaluate the floristic composition and the
phytosociological parameters of the adult woody component in an area of degraded
riparian forest in the municipality of Livramento, Semiarid region of Paraíba. The
ecological system chosen to carry out the work was the riparian forest of the Verde
creek (7º19'5.46'' S and 36º55'29.28'' W; 568 m altitude), with a total of 50 contiguous
plots of 10 x 10 m, distributed along the watercourse. The inclusion criteria were to
sample shrub-tree individuals, living and dead, standing, with stem diameter at ground
level (DNS) ≥ 3 cm and total height ≥ 1 m. The absolute and relative values for density,
frequency and dominance were calculated, and the values of coverage and importance
too. Diversity and equability values were also calculated. The individuals were
systematized into diametric and hypsometric classes. The shrub-tree community of the
riparian area sampled was represented by 23 species, one of which remained
undetermined. The identified species were distributed across 20 genera and 11
families. The families with the largest number of species were Fabaceae (eight),
Euphorbiaceae (four) and Cactaceae (two). A total of 1050 individuals belonging to the
shrub-arboreal component were registered in the phytosociological structure. The
species that presented the greatest abundance were Mimosa tenuiflora (Willd.) Poir.
(508), Croton blanchetianus Baill. (173), Jatropha mollissima (Pohl) Baill. (81) and
Cenostigma pyramidale (Tul.) Gagnon & G.P. Lewis (58). M. tenuiflora presented the
highest values in phytosociological parameters. Particularly related to the Importance
Value (VI), the species that stood out the most were M. tenuiflora (123.56), C.
blanchetianus (32.32), J. mollissima (24.28), C. pyramidale (18.39) and C. flexuosa
(12.90), in addition to the category of the dead with 20.69. The diversity and equability
values were 1.86 nats.ind.-1 and 0.59 respectively. Considering the diameter
distribution, a predominance of individuals in the third (9.1 to 12 cm), fourth (12.1 to 15
cm) and fifth class (15.1 to 18 cm) was observed. Thus, these three classes
corresponded to a total of 688 individuals, representing 65.52% of the total number of
individuals sampled. Evaluating the hypsometric distribution data, it was observed that
the largest number of individuals was also included between the third and fifth class
(range of 3 to 6 m in height), with these intervals containing 679 individuals, which
represents 64.67% of the total number of individuals sampled. Therefore, the data
obtained is defined as relevant to support conservation and restoration strategies for
riparian areas in the context of the Brazilian Semiarid region, thus adhering to
objectives 6 and 15 of the SDGs of the 2030 agenda.