No abstract

A catalogue is presented of plant names in use in the Caatinga Phytogeographical Domain (CPD), the largest semiarid ecoregion of South America. We compiled all pubished papers we could locate with floristic and/or phytosociological data relating to the CPD and created a database of all site-based surveys, all names reported in these surveys and the basic ecological data associated with each species. We then mapped the names used in survey reports to those currently accepted in Brazil, consulting specialists to resolve taxonomic and nomenclatural issues before synthesizing the data in order to present here a list of all names in use. Thus this compilation represents the taxonomic data in use by generalist botanists on a sub continental scale. Synthesizing the previously dispersed ecological data available for the species, we explored general ecological patterns in the CPD. We also classified each survey as documenting the flora of a specific type of environment within the CPD and compared the general floristic resemblance between different environments within CPD on a biogeographical scale. Rarefaction curves and species richness estimator indices were employed in order to address the question as to whether or not the Caatinga Phytogeographical Domain can be described as well-sampled. To date over 1700 species have been reported in site-based floristic and phytosociological studies in the CPD. Most surveys focused only on woody plants, ignoring the non woody component, but we show here that a large proportion of the plant biodiversity in the Caatinga is comprised of non woody plants. We estimate that 40% of the existing species were not sampled by site-based surveys. Moreover, most of the species in our database were recorded from a single site, while a few species were considered widespread. When comparing the number of widespread species in our dataset to results published for the cerrado savannas, we show that species in Caatinga seems to have a much more restricted distribution than plants in the Cerrado. We present here a catalogue of all plant names recorded and discuss sampling and geographical issues related to the floristic study of Caatinga.

RESUMO(Alienígenas na sala: o que fazer com espécies exóticas em trabalhos de taxonomia, florística e fitossociologia?): A presença cada vez mais disseminada de organismos exóticos (muitos dos quais se tornam invasores) nas diferentes regiões do planeta levou ao surgimento de uma linha de pesquisa na ecologia voltada às invasões biológicas. E para permitir a comunicação entre autores também foi desenvolvido um arcabouço terminológico. Mas, apesar disso, a terminologia relativa às bioinvasões tem sido ignorada por boa parte dos botânicos no Brasil. Há uma boa dose de confusão entre botânicos sobre o que seja uma espécie exótica, naturalizada, invasora, daninha e ruderal, levando ao uso inconsistente da terminologia. Além disso, diferentes autores têm adotado posturas praticamente opostas ao lidar com espécies exóticas em suas áreas de estudo, seja na preparação de tratamentos taxonômicos, seja na publicação de levantamentos florísticos e fitossociológicos. Enquanto alguns pesquisadores incluem em floras mesmo espécies cultivadas que não se reproduzem, outros excluem plantas invasoras comuns e conspícuas. Nós apresentamos aqui, em português, os principais conceitos relativos ao tema da bioinvasão e chamamos a atenção dos autores brasileiros para a necessidade de utilizar de modo consistente o arcabouço terminológico já existente na literatura. Também propomos a adoção de rótulos claros para informar quais espécies são exóticas na área estudada, diferenciando-as das nativas, e sugerimos critérios para ajudar botânicos a decidirem quando uma planta exótica deve ou não ser incluída em tratamentos taxonômicos ou levantamentos de florística. Palavras-chaves: Conceitos, espécies exóticas, invasões biológicas, floras ABSTRACT(Aliens in the room: what to do with exotic species in taxonomic, floristic and phytosociological studies?): The ever--growing presence of exotic organisms (many of which become invasive) throughout the planet has led to the emergence of biological invasions as a field of study within ecology. To enable communication between scientists in this field, a terminology has developed. However, this terminology has been ignored by many botanists in Brazil where there is confusion regarding definition of exotic, naturalized, invasive, weed and ruderal species, leading to inconsistent use of the concepts. Moreover, different authors have adopted antagonistic positions when dealing with exotic species existing in their study areas, either in the preparation of taxonomic treatments or in floristic and phytosociological surveys. While some authors include in floras cultivated, non reproducing species, others exclude even widespread and common invasives. We present here, in Portuguese, the main concepts related to the theme of bioinvasion and draw the attention of Brazilian authors to the necessity for consistent use of the terminological framework available for biological invasions. We also propose that authors should clearly label exotic plants reported in their work, differentiating exotics from native species...

Recebido em 15/06/2002. Aceito em 08/04/2004 RESUMO -(Flora e aspectos auto-ecológicos de um encrave de cerrado na chapada do Araripe, Nordeste do Brasil). Este trabalho visa conhecer a composição e riqueza florística, os padrões fenológicos reprodutivos, as síndromes de dispersão e as formas de vida das espécies de uma disjunção de cerrado em clima semi-árido, na chapada do Araripe, Estado do Ceará. Foram encontradas 107 espécies e 41 famílias. Fabaceae, Myrtaceae, Poaceae, Apocynaceae, Euphorbiaceae e Malpighiaceae foram as mais ricas em espécies. Foi feita a distribuição geográfica de 47 espécies arbustivas e arbóreas em 27 listagens de cerrados brasileiros. Doze espécies apresentaram ampla distribuição geográfica e 13 foram registradas apenas neste trabalho. Cerca de 76% das espécies floresceram e frutificaram no período chuvoso. As síndromes de dispersão predominantes foram: zoocoria, autocoria e anemocoria. O espectro biológico foi predominantemente constituído por fanerófitos (50,7%), hemicriptófitos (14,9%) e caméfitos (13,1%). O cerrado estudado apresentou menor riqueza taxonômica que os cerrados contínuos e comportamento das fenofases reprodutivas, percentagem de síndromes de dispersão e formas de vida similares. Palavras-chave: cerrado, flora vascular, dispersão, fenologia, formas de vidaABSTRACT -(Flora and autecology's aspects of a disjunction cerrado at Araripe plateau, Northeastern Brazil). This study subject to investigate the floristic composition and richness, the reproductive phenological patterns, the dispersal syndromes and life forms of species of a disjunt cerrado in semiarid climate at Araripe plateau during a one year period. We found 107 species and 41 families. Fabaceae, Myrtaceae, Poaceae, Apocynaceae, Euphorbiaceae and Malpighiaceae showed the largest number of species. For 47 of the woody species found, we studied the geographical distribution based on 27 papers of the Brazilian cerrados. Twelve species are of widespread occurence in the cerrado, and 13 are restricted to the Araripe plateau. Zoocory, autocory, and anemocory are the predominant syndromes of dispersal. The predominant life forms were phanerophytes (50.7%), hemicriptophytes (14.9%) and camephytes (13.1%). The cerrado of Araripe have lower species richness than continous cerrados, but a similar pattern of reproductive phenology, dispersal syndromes and life forms in more humid zones.

Seasonally dry tropical plant formations (SDTF) are likely to exhibit phylogenetic clustering owing to niche conservatism driven by a strong environmental filter (water stress), but heterogeneous edaphic environments and life histories may result in heterogeneity in degree of phylogenetic clustering. We investigated phylogenetic patterns across ecological gradients related to water availability (edaphic environment and climate) in the Caatinga, a SDTF in Brazil. Caatinga is characterized by semiarid climate and three distinct edaphic environments – sedimentary, crystalline, and inselberg –representing a decreasing gradient in soil water availability. We used two measures of phylogenetic diversity: Net Relatedness Index based on the entire phylogeny among species present in a site, reflecting long-term diversification; and Nearest Taxon Index based on the tips of the phylogeny, reflecting more recent diversification. We also evaluated woody species in contrast to herbaceous species. The main climatic variable influencing phylogenetic pattern was precipitation in the driest quarter, particularly for herbaceous species, suggesting that environmental filtering related to minimal periods of precipitation is an important driver of Caatinga biodiversity, as one might expect for a SDTF. Woody species tended to show phylogenetic clustering whereas herbaceous species tended towards phylogenetic overdispersion. We also found phylogenetic clustering in two edaphic environments (sedimentary and crystalline) in contrast to phylogenetic overdispersion in the third (inselberg). We conclude that while niche conservatism is evident in phylogenetic clustering in the Caatinga, this is not a universal pattern likely due to heterogeneity in the degree of realized environmental filtering across edaphic environments. Thus, SDTF, in spite of a strong shared environmental filter, are potentially heterogeneous in phylogenetic structuring. Our results support the need for scientifically informed conservation strategies in the Caatinga and other SDTF regions that have not previously been prioritized for conservation in order to take into account this heterogeneity.

RESUMO Comunidades de plantas sobre afloramentos rochosos no semi-árido brasileiro ainda são pouco conhecidas para a ciência. O município de Quixadá, no semi-árido cearense, destaca-se pela grande concentração de elevações de ilhas rochosas. Este estudo tem por objetivos levantar e analisar a composição, o espectro biológico e as síndromes de dispersão das espécies que ocorrem em um inselbergue no município de Quixadá, Ceará, e a similaridade florística deste com as espécies da vegetação circundante. Em 2000, foram realizadas coletas mensais de espécies e classificadas quanto às formas de vida e síndromes de dispersão em uma área situada a 4º 57'S e 39º 01'W e 270 m de altitude. A similaridade da flora com o entorno foi analisada através do índice de Jaccard. Foram inventariadas 77 espécies, 66 gêneros e 36 famílias. As porcentagens do espectro biológico foram: terófitos (44,2), fanerófitos (24,7), caméfitos (14,6), hemicriptófitos (13,4), geófitos (2,6) e aerófitos (1,2) e as do espectro de dispersão: anemocoria (49), autocoria (35) e zoocoria (16). A similaridade com flora do entorno foi de 13% (21 espécies), demonstrando que a caatinga local é a potencial fonte de propágulos. Os terófitos são as formas de vida dominante nos inselbergues de regiões áridas e semiáridas, cuja flora também é predominantemente dispersa por fatores abióticos, principalmente o vento. Assim, este estudo confirma o padrão esperado para os atributos síndromes de dispersão e espectro biológico da vegetação sob climas áridos e semi-áridos.

Foi caracterizada a composição florística da vegetação de carrasco do sul do planalto da Ibiapaba em Novo Oriente, Ceará (5°28’ - 5°43’S e 40°52’ - 40º55’W ; 750-850 m de altitude), ocorrendo em Areias Quartzosas profundas. Foram coletadas 184 espécies, incluindo ervas, cipós, subarbustos, arbustos e árvores, distribuídas em 52 famílias. As famílias com maior número de espécies foram Caesalpiniaceae (17), Fabaceae (16), Euphorbiaceae (15), Myrtaceae (11), Bignoniaceae (10) e Mimosaceae (9). De 102 espécies arbustivas e arbóreas da área estudada, 24 ocorreram em áreas de caatingas e cerrados, 29 em cerrados, 17 em caatinga, uma espécie em mata e 31 foram exclusivas do carrasco. Não foi possível definir se o carrasco é um cerradão degradado ou um tipo próprio de vegetação, sendo necessária para isso a realização de levantamentos em outras áreas similares.
The floristic composition of the vegetation in the southern part of the Ibiapaba plateau was studied at Novo Oriente, Ceará - Brazil (5°28’ - 5°43’S and 40°52’ - 40º55’W ; 750-850 m altitude). A total of 184 species in 52 families was collected, including herbs, vines, shrubs and trees. Families with the highest number of species were Caesalpiniaceae (17 species), Fabaceae (16 species), Euphorbiaceae (15 species), Myrtaceae (11 species), Bignoniaceae (10 species) and Mimosaceae (9 species). Of 102 shrub and tree species in the area, 24 occurred in both caatinga and cerrado, 29 in cerrado, 17 in caatinga, one in forest and 31 only in carrasco. It is not yet possible to define whether carrasco is a degraded cerradão or a type vegetation on its own. Surveys in other carrasco areas are necessary in order to contribute to solve this problem

To test whether the flora is organized in discrete or continuous units along a topographic gradient, three physiognomies were assessed on different soil classes in a semi-arid region of northeastern Brazil: caatinga (xeric shrubland) at altitudes from 300 to 500 m, deciduous forest at altitudes from 500 to 700 m and carrasco (deciduous shrubland) at 700 m. In each physiognomy a species inventory was carried out, and plants were classified according to life- and growth-forms. Species richness was higher in the deciduous forest (250) than in the carrasco (136) and caatinga (137). The caatinga shared only a few species with the carrasco (6 species) and the deciduous forest (18 species). The highest species overlap was between the deciduous forest and the carrasco (62 species). One hundred and four species occurred only in the caatinga, 161 only in the deciduous forest and 59 only in the carrasco. Woody species predominated in physiognomies on sedimentary soils with latosol and arenosol: 124 species occurred in the deciduous forest and 68 in the carrasco. In the caatinga on crystalline basement relief with predominance of planosol, herbs showed the highest species richness (69). Comparing the biological spectrum of Brazilian plant life-forms, the caatinga stood out with higher proportion of therophytes and chamaephytes. Considering the flora of the three phytophysiognomies studied here, we can affirm that the caatinga is a discrete floristic unit.