Sugarloaf Land in south-eastern Brazil: a tropical hotspot of lowland inselberg plant diversity.

BACKGROUND: Isolated monoliths of granitic and/or gneissic rock rising abruptly from the surrounding landscape are known as inselbergs. Dome-shaped inselbergs are common throughout the Atlantic Forest in south-eastern Brazil, a region known as Sugarloaf Land (SLL). This study aimed to create the first checklist of vascular plant species occurring on lowland inselbergs in SLL, with a focus on vegetation islands. We used information from online databases, our own field sampling and data from previously-published studies. We found 548 vascular plant species (505 angiosperms; 43 ferns and lycophytes) belonging to 69 families and 212 genera. Of all identified species, 536 are native and 12 are naturalised. NEW INFORMATION: We updated the information currently available in Flora do Brasil 2020, as 59% of the angiosperms and 63% of the ferns and lycophytes on our checklist were not previously characterised as occurring on rock outcrops. As a first step towards generating a Virtual Herbarium of lowland inselberg vascular plants, we added barcode vouchers with images available online for 75% of the total number of vascular species. In the official lists of endangered species, 115 angiosperms and five ferns and lycophytes are mentioned. However, the conservation status of many species have not yet been evaluated (77% angiosperms; 88% ferns and lycophytes), thus this list is an important step towards their conservation. The information provided herein is essential for management programmes related to rock outcrops in Brazil as they are facing serious threats to conservation.

Tree species diversity of coastal lowland semideciduous forest fragments in northern Rio de Janeiro State, Brazil / Diversidade de espécies arbóreas em fragmentos de floresta semidecidual de terras baixas costeiras no norte do Estado do Rio de Janeiro, Brasil

Habitat destruction has caused Brazilian coastal lowland semideciduous forests to suffer severe fragmentation. In the state of Rio de Janeiro, especially in the northern region, these fragments are under severe threat of destruction, while data on their floristic diversity and community structure are still lacking. In this study, six secondary forest fragments (henceforth called sites) of coastal lowland semideciduous forests with areas ranging from 13 to 1200 ha were studied. The objective was to evaluate the structure and diversity of trees of these sites and relate them to the conservation status of this region. Five plots of 20 x 20 m were established in each site, totalling a sample area of 1.4 ha and all trees with DBH 5cm were sampled. The families with the highest species richness were Fabaceae, Sapotaceae, Myrtaceae and Meliaceae. The most abundant species were: Metrodorea nigra, Pseudopiptadenia contorta and Senefeldera verticillata. The richness, evenness and Shannon diversity values ranged from 59 to 89 species, 0.75 to 0.87 and from 2.59 to 3.79 nats.ind-1, respectively. Sites showed high floristic similarity. The tree density values varied from 1410 to 1840 ind.ha-1 and were within the levels expected for semideciduous forest; however, the basal area values (19.8 to 28.0 m2.ha-1) are those usually observed in disturbed forests. Despite being secondary forests, the sites had high species diversity with occurrence of tree species of recognized conservation value. Urgent action must be taken to manage and conserve these forests, such as: (i) forest corridors establish connecting fragments especially using zoochorous tree species, and (ii) use forest enrichment techniques using species that are absent or presently at low density as a result of intensive exploitation in the past.

A destruição de habitat levou as florestas estacionais semideciduais de tabuleiro brasileiras a sofrerem intensa fragmentação. No estado do Rio de Janeiro, especialmente na região norte, esses fragmentos estão sob grave ameaça de destruição e os dados sobre a florística, diversidade e estrutura da comunidade ainda são insuficientes. Neste estudo, seis fragmentos secundários de florestas semidecíduas costeiras de baixa altitude, com áreas variando de 13 a 1200 ha foram estudados. O objetivo do presente trabalho foi avaliar a estrutura e a diversidade arbórea nesses locais e relacionar esses dados com o estado de conservação da região. Cinco parcelas de 20 x 20 m, foram alocadas em cada local, totalizando uma área amostral de 1,4ha e todas as árvores com DAP 5cm foram amostradas. As famílias com maior riqueza de espécies nas áreas foram Fabaceae, Sapotaceae, Myrtaceae e Meliaceae. As espécies mais abundantes nas áreas foram: Metrodorea nigra, Pseudopiptadenia contorta e Senefeldera verticillata. Os valores de riqueza, diversidade de Shannon e eqüitabilidade, variaram de 59 a 89 espécies, 0,75 a 0,87 e 2,59 a 3,79 nats.ind-1, respectivamente. Foi encontrada alta similaridade florística entre as áreas. Os valores de densidade de árvores variou de 1410 a 1840 ind.ha-1, estando dentro do esperado para uma floresta estacional semidecidual, no entanto, os valores de área basal (19,8-28,0 m2.ha-1) são normalmente observados em florestas perturbadas. Apesar dos fragmentos estudados serem florestas secundárias, os mesmos apresentaram alta diversidade, com ocorrência de espécies de valor conservacionista reconhecido. Medidas urgentes devem ser tomadas para o manejo e conservação dos remanescentes de florestas de tabuleiro, tais como: (1) corredores florestais devem ser definidos conectando fragmentos, especialmente utilizando espécies de árvores zoocóricas e (2) técnicas de enriquecimento florestal, utilizando espécies que estão ausentes ou ocorrem com baixa densidade como resultado da exploração intensiva no passado.