The flora and vegetation of rocky outcrops in three municipalities in the northern region of Ceará, Brazil: phytosociological characterization

Abstract

In this study, we aim to identify flora and vegetation of low-elevation rocky outcrops (lajedos) in “Caatinga Arbustiva Aberta” (open shrublands) to propose a phytosociological classification for xerophilous communities. The study areas are located at the municipalities of Sobral, Groaíaras and Santa Quitéria (Ceará state, Brazil). We selected five stations comprising areas with high proportion of bare rocks (> 80%), and the field work were conducted in March 2014 and 2015 respectively (3º56’S and 40º23’W, 4º01’S and 40º05’W, 4º07’S and 40º08’W, 4º09’S and 40º09’W and 4º03’S and 40º00’W). We have applied the TWINSPAN (two-way indicator species analysis) and Braun-Blanquet methods. The minimum areas of phytosociological inventories ranged from 8 to 16 m². Floristic relevés were made and all the plant species growing in cracks, crevices and small vegetation "islands" were identified. The floristic list is composed of 88 species, distributed in 59 genera and 30 families. Fabaceae was the most representative in species richness, 20 species, followed by Poaceae (10 spp.), Euphorbiaceae (7 spp.) and Convolvulaceae (6 spp.). We identified 19 Brazilian endemisms. Following phytosociological analysis of vegetation we found two different communities: Pilosocereus gounellei FA.C.Weber) Byles & Rowley and Encholirium spectabile Mart. ex Schult. & Schult.f. and the Crateva tapia L. and Combretum leprosum Mart.

Key words:
semiarid; floristic list; xerophytes; Caatinga; phytosociology