Ecological Attributes, Geographic Distribution and Endemism of Cacti from the São Francisco Watershed

Abstract

The purpose of this study is to assess the ecological attributes, geographic distribution, conservation status and endemism of cactus species in the São Francisco River Watershed (SFRW). In order to gather information on the cactus species found in the SFRW, three sources of information were used: collections from Brazilian herbaria, bibliographic references and online collections. The ecological attributes were related to (1) habitat specificity, (2) species habit, (3) pollination syndrome, and (4) groups of primary and secondary dispersers. Moreover, data from the three information sources cited above were used to assess geographic distribution of the cacti found in the SFRW. Species were divided into three categories according to the number of populations sampled: (1) widespread species: over 30 populations, (2) species with intermediate distribution: 11 to 30 populations, (3) locally distributed species: up to 10 populations. Conservation status of the cacti found in the SFRW was determined according to the classification of the International Union for Conservation of Nature and Natural Resources Red List. There were 108 cacti taxa scattered throughout the SFRW and 32.4% of the taxa are endemic. Species may be present in more than one ecosystem; most were found in areas of Caatinga (59.5%). The most common microhabitat was soil (62.5%). The globose habit (21.2%), columnar habit (29.8%) and shrubby habit (36.5%) are more frequent. The main pollination syndrome is chiropterophily (34.5%). All Cactaceae found in the SFRW produce fruits that are dispersed by animals and vertebrates are the main agents of zoochoric dispersal. The conservation status of these cacti is cause for worry, because many species are classified as vulnerable or critically endangered.