Situação amostral e riqueza de espécies das Angiospermas do estado do Ceará, Brasil

Abstract

(Sampling effort and species richness of Angiosperms in the state of Ceará, Brazil). The state of Ceará, located in northeast Brazil, has a predominantly semi-arid climate. To guide future inventories of the fl ora, a preliminary survey of collections in the state was made, where we analyzed sampling effort and species richness of Asteraceae, Euphorbiaceae, Fabaceae, Poaceae and Rubiaceae. Geographic distribution of the samples was correlated to the seven phytoecological units of Ceará state: caatinga arbustiva, caatinga arbórea, carrasco, cerradão, complexo litorâneo, mata seca and mata úmida. The data were obtained from the Prisco Bezerra Herbarium (EAC) collection and were combined using the software BRAHMS. From 1933 to August 2008, this collection registered the following: 11,551 exsiccatae (exs.) representing 1,209 species (spp.). This total number of exsiccatae is distributed as follows among the phytoecological units: mata úmida 27% exs. and 33% spp., complexo litorâneo 24% exs. and 24% spp., caatinga arbustiva 16% exs. and 19% spp., carrasco 13% exs. and 17% spp., mata seca 10% exs. and 9% spp., caatinga arbórea 8% exs. and 12% and cerradão 2% exs. and 3% spp. These data reveal greater collection effort and species richness in areas of mata úmida and complexo litorâneo, followed by areas of caatinga arbustiva and caatinga arbórea. With only 5% of Ceara’s territory, sampling in mata úmida surpasses that in caatingas, the latter with 70% of the state´s territory. Therefore, a satisfactory number of collections in mata úmida was observed to the detriment of other units, making it necessary to draw up new projects aimed at a greater effort in these sub-sampling collection areas