Vegetation Structure in Two Anthropic Fragments of Caatinga in Paraiba State, Brazil

ABSTRACT This study aimed to assess the floristic and structural differences between two contiguous fragments of Caatinga vegetation in Paraiba state, Brazil. To this end, 25 plots of 20 × 20 m were allocated in each area (A and B), and all individuals with circumference at soil level ≥ 10 cm and height ≥ 1 m were sampled. Area A: 2.226 individuals of 21 species, 21 genera and 11 families. Area B: 1.930 individuals of 17 species, 16 genera and 9 families. The Shannon-Wienner index and Pielou equability values were 1.92 nats/ind. and 0.63 (area A), and 1.76 nats/ind. and 0.62 (area B), respectively. The Sørensen’s similarity index between the areas was 79%. Poincianella pyramidalis, Mimosa tenuiflora, Aspidosperma pyrifolium, Croton blanchetianus, and Combretum leprosum were the richest species found in both areas. The floristic and structural parameters measured in both areas showed differences between them, most likely because of the different levels of anthropic intervention, which were larger in the B area.

摘要 本研究旨在评估巴西帕拉伊巴州境内两片相邻的卡廷加植被（Caatinga）片段的区系组成与结构差异。为此，在A、B两个研究区域内各设置25个20×20米的样地，对土壤围径≥10厘米、株高≥1米的所有植株个体开展取样调查。A区域共计2226株个体，隶属于21种、21属及11个科；B区域共计1930株个体，隶属于17种、16属及9个科。A区域的香农-维纳多样性指数与皮洛洛均匀度指数分别为1.92奈特/个体与0.63，B区域则分别为1.76奈特/个体与0.62。两区域间的索伦森相似性指数为79%。锥果盾木（Poincianella pyramidalis）、细花含羞草（Mimosa tenuiflora）、柳叶阿斯庇树（Aspidosperma pyrifolium）、布兰奇巴豆（Croton blanchetianus）以及瘦萼风车子（Combretum leprosum）为两个区域中均分布的优势物种。本研究测得的两区系组成与结构参数均存在显著差异，该差异极大概率源于人类活动干预程度的差异：B区域受到的人为干扰强度更高。