Climate change, together with human activities, impacts on natural and human systems on all continents and poses a major threat to biodiversity, especially in environments with a high rate of endemism and where species are profoundly adapted to specific environmental conditions, as is the case of the seasonally dry tropical forests, noticeably the Caatinga, an exclusively Brazilian biome. The objective of this study was to build spatial niche models of five species of Cactaceae (Arrojadoa penicillata, Brasilicereus phaeacanthus, Pereskia aureiflora, Stephanocereus leucostele and Tacinga inamoena) endemic to the Caatinga and with different traits, to evaluate the impact of climate change on their geographical distribution. The species records and environmental variable values were overlaid on a grid of 6818 cells with 0.5° spatial resolution. Niche models were obtained for five types of general circulation models between ocean and atmosphere and 12 different ecological models. The ensemble ecological niche model was calculated at present and projected to past (last glacial maximum – LGM, 21 000; and mid‐Holocene – Hol, 6000 years ago) and future climate conditions (average of 2080), under the effect of climate change, in the greenhouse gas emission scenario RCP4.5. The distribution pattern of the studied species indicates an area with less environmental suitability in the LGM, followed by an expansion that began in the Hol and continued until the present period. In the future (2080), the models predicted a retraction of areas of environmental suitability, in which P. aureiflora and B. phaeacanthus, given their more restricted, marginal habitat and woody habit, present a great risk of extinction, whilst S. leucostele, A. penicillata and T. inamoena present a smaller reduction in suitable area, partly reflecting their spreading, less woody habit. Regional conservation actions for Cactaceae species and their habitat need to take these findings into account if we are to ensure the survival of these species.
Epiphytism in the Caatinga biome is still poorly studied. In this biome, the licuri palm (Syagrus coronata) is an important phorophyte of several species. In this study, epiphytes were surveyed on licuri palms in order to infer the conservation degree of a Caatinga area. A total of 496 individuals of S. coronata were sampled, in a toposequence in five areas: pasture with licuri (anthropized area), lowland, slope, hilltop and rocky outcrops of an inselberg (conserved areas) and in the community of Jatobá, municipality of Milagres (Bahia, Brazil). Fifty-seven species were identified, encompassing 38 genera and 17 families, growing on licuri palms. The family with the largest number of species was Bromeliaceae (21 species), followed by Orchidaceae, Cactaceae and Polypodiaceae with five species each. In Caatinga vegetation with palm species, the epiphytes on the licuri palm can help the reforestation process, the licuri palm being the key species, where the associated epiphytism demonstrates the dispersion of numerous species. It is a suspended seedlings bank with a nurse plant, where recurring families such as Bromeliaceae, Cactaceae, Orchidaceae, Araceae occur as strategic components in sustainable agroecosystem designs.
Teve-se como objetivo no presente estudo teve como objetivo listar as espécies ocorrentes em uma área de restinga em Jaguaripe, Bahia, caracterizando as espécies quanto ao endemismo e distribuição, além de relacioná-las com as distintas fitofisionomias encontradas. As coletas ocorreram periodicamente entre junho de 2014 e agosto de 2017. Na área de estudo, foram coletadas 195 espécies, distribuídas em 150 gêneros e 65 famílias. As famílias mais diversas foram Fabaceae e Rubiaceae, enquanto Myrcia DC. foi o gênero mais representativo. Entre os hábitos encontrados, as herbáceas foram os que apresentaram maior número de espécies (90), seguido por arbustos (61), trepadeiras (24) e árvores com 20 espécies. Estudos florísticos em outras restingas da Bahia têm apontado a ocorrência das mesmas famílias como as de maior riqueza em espécies, entretanto, o número de espécies do presente estudo enquandraram-se entre os mais baixos do estado. Diversas espécies são endêmicas do domínio fitogeográfico da Floresta Atlântica, da restinga ou do estado da Bahia. Cinco espécies são invasoras ou naturalizadas. Os dados obtidos no presente estudo podem subsidiar ações de conservação das restingas da costa do Brasil.
Commelinaceae is an important component of the Atlantic Forest and its analysis can provide information on the conservation of that species. This study had the objective of analyzing the phenology and floral and reproductive biology of Dichorisandra rhizantha, growing in an Atlantic Forest fragment, to obtain data related to the form of reproduction and pollination mechanism of this species. We monitored the phenophases and reproductive biology of the D. rhizantha in the area studied using different methodologies and microscopy techniques (LM, SEM and FM). The flowering period occurs during the dry season. The species is andromonoecious and has daytime anthesis (4:30 a.m.-1:30 p.m.). It has purple zygomorphic flowers and rimose but functionally poricidal anthers. The pollen viability was 97.6% and the two floral morphs investigated contained a large quantity of pollen grains. The time of greatest stigma receptivity (anthesis) coincided with the pollen viability. Cross-pollination was the only efficient reproductive system of the species, with observation of gametophytic self-incompatibility and pollen tubes growth only as far as the middle or lower third of the pistil. We observed bee species of the genera Xylocopa and Euglossa visiting the flowers and acting as effective pollinators. The immature fruits were formed after about 3.25 ± 1 days, and the presence was noted of ants of the genus Cephalotes acting as dispersers of the seeds, with aril serving as the reward. Although the natural reproductive system is efficient, D. rhizantha is endangered, mainly due to fragmentation of habitat caused by deforestation and urban encroachment.
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