The first botanical explorations of bryophyte diversity in the Brazilian Amazon mountains: high species diversity, low endemism, and low similarity

摘要

We investigated the species richness, endemism, and similarity of the bryoflora (mosses and liverworts) on five Brazilian Amazon mountains (four Tepuis and one rocky outcrop), to determine the floristic relationships between them using presence/absence matrix. Cluster analysis based on the Jaccard index was used to determine similarities between the plant assemblages in five areas. We also performed a principal component analysis to determine which abiotic variables best explained the variations between those mountains. We surveyed the bryophyte species on each of the five mountains to identify the diversity of mosses and liverworts and to answer to the following questions: (1) How many bryophyte species are there in total area (gama diversity) and on each mountain (alpha diversity)? (2) Do mosses and liverworts share patterns of diversity? (3) Can patterns of alpha diversity be used to predict patterns of beta diversity? (4) What are the species distribution patterns? (5) How many endemic species are there in the mountains? and, (6) Is there high similarity among those bryophyte floras? We encountered 425 species, 144 genera, and 51 families of bryophytes, with Lejeuneaceae and Lepidoziaceae being the richest families. A considerable number of floristic novelties were encountered: 18 species new to Brazil; 39 species new to northern Brazil; 21 species new to Amazonas State; and 2 species new to science and only recently described. Over 43% of the bryophytes have a tropical America distribution, approximately 7% are Pantropical, 6.5% are Afro-American, and 3% are endemic to Brazil (6 liverworts and 6 mosses), and 6% are widespread globally. We present a checklist of 425 bryophyte species (144 genera and 51 families) of which 12 are endemic. Patterns of endemism of the bryophyte flora on the Tepuis differ from those exhibited by angiosperms (in the latter three times higher). Thirty-nine of these species were new for the Amazonia domain in Brazil, increasing by 7% the previous total of Amazonian recorded species. The similarity between sites was low, ranging from 3 to 25%. PCA analysis showed temperature variables explaining the greater part of the variance (76.6%) between the mountains. Our results demonstrate that patterns of alpha diversity cannot be used to predict patterns of beta diversity. This paper represents the first evaluation of bryophytes on five Brazilian Amazon mountains, giving insight into their species richness, endemism, and similarity, and providing baseline information for analyzing species' turnover rates, migration, invasion events, etc. These results also represent an increase in our general knowledge of the Brazilian bryoflora and are relevant to the conservation of bryophyte diversity in the Amazon forest, and represent a contribution toward the targets of the Global Strategy for Plant Conservation.