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Ecology

The power of nymphs

Bromeliads are crucial to the functioning of the northeastern Mata Atlântica coastal rain forest and help to provide guidelines for its preservation

ELTON LEMEHohenbergia catingaeELTON LEME

Stiff serrated points decorated with thin red stripes perforate the layer of organic matter lying on the forest floor. These are the leaves of the Cryptanthus felixii, a bromeliad from the state of Pernambuco, from whose base greenish tubes extend, ending in delicate white petals that are particularly alluring for bees, which absorb their nectar and aid pollinization. Vriesea freicanecana bromeliads stick to the naked rock where bats transfer pollen from one flower to the next. Only that way can fruit be formed. They hang from the tip of branches exposed to the wind – which is responsible for spreading the seed to other hills. From the rain water that gathers in the Neoregelia silvomontana high up, in the top of the trees of the inner state area in Bahia, little white flowers emerge. Monkeys know that there they will find insects and tadpoles, important sources of protein. The plants described above are only some of the northeastern species discovered by José Alves Siqueira Filho, from the Vale do São Francisco Federal University Foundation in Pernambuco, whose work has been showing the importance of the key role of bromeliads in the ecology of the Mata Atlântica rainforest.

Like the Greek nymphs, they are everywhere in the forest and they provide nourishment for humming birds, bats and insects, as well as essential shelter for the reproduction of tree frogs and other animals, and an environment in which other plants germinate. Some species of bromeliads are found in tree tops and only reproduce with the aid of animals, which transfer pollen to other flowers and seeds, in places where they can germinate. This interdependence between bromeliads and other forest inhabitants means that they are a key part of the ecosystem and that they indicate the earliest signs of forest deterioration. “Bromeliads function as bioindicators that tell the story of the Mata Atlântica forest”, says Siqueira Filho. Together with Isabel Cristina Machado, from UFPE, the Federal University of Pernambuco, he showed that bromeliads depend primarily on vertebrate animals to reproduce and that they are the chief source of nourishment for hummingbirds. Of the 39 species studied, 60% are pollinized by birds, 26% by bees, 11% by bats and 3% by butterflies. As for the seeds, they are spread largely by birds (40%), mammals (11%) and ants (6%). However, in many of the areas that the two scientists examined, they were unable to find the required pollinizing or dispersing agent. The localized extinction of animals could mean the beginning of the end of the bromeliads that depend on them. These data are among the original articles of the book Fragmentos da Mata Atlântica no Nordeste (Fragments of the Mata Atlântica rainforest in the Northeast), organized by Siqueira Filho and Elton Leme, from the Getúlio Vargas Foundation Law School in Rio de Janeiro.

The most serious threat to biodiversity is that the forest is shrinking in unconnected places – within ecologically incomplete islands, both animals and plants have to move between fragments in order to survive. With this in mind, Marcelo Tabarelli, a botanist from UFPE, carried out a computer simulation of the movement of animals between parts of the forest linked by corridors. The study shows that north of the São Francisco river, viable ecosystems would require the establishment of 9 to 32 kilometers of corridors. Furthermore, the disappearance of vertebrate animals interrupts the dispersal of seeds and can lead to the extinction of 30% of the region’s trees and shrubs. Tabarelli foresees that the forest in the future will have less diversity, species that need shade will become rarer and species that are rare today will disappear altogether. Siqueira Filho analyzed the distribution of bromeliads in the states of Pernambuco and Alagoas and saw that more than 60% of the species are in danger of disappearing in these states, whereas 41 species that only exist there are at the doors of total extinction. In some places, he observed an invasion of plants from Brazil’s Caatinga, the semi-desert scrublands; this could be the start of a drastic landscape change.

ELTON LEMENeoregelia pernambucanaELTON LEME

Before and now
The destruction of the forest has historical roots that extend back to the discovery of Brazil. Clóvis Cavalcanti, a UFPE professor who is an expert on the socioenvironmental aspects of the Mata Atlântica rainforest, explained that the colonizers found such exuberant vegetation in Brazil that it struck them as being infinite. The same point of view persisted among their descendants, such as Cavalcanti himself, who grew up thinking that the forest would always be there, even though sugarcane is what put the bread on his family’s table. Deforestation to establish sugarcane plantations expanded in the 70’s, as a result of the fuel alcohol program. “It was due to this initiative, regarded as environmentally sound – because it would avoid burning fossil fuels, replaced by sugarcane ethanol – that almost all the last islands in the forest covering the top of the hills in the Pernambuco Zona da Mata rainforest disappeared altogether”, writes Cavalcanti. By 1990, the northeastern Mata Atlântica forest covered less than 6% of its original area, and from 1989 to 2000 it lost 10% of its vegetation cover.

The loss of the Mata Atlântica rainforest north of the São Francisco river is especially serious because this region has particularities that make it outstanding. In a study published this year in the Journal of Biogeography, Tabarelli analyzed 452 tree species in the region and showed that the Pernambuco forest is closer to the Amazon forest than to the Mata Atlântica south of the São Francisco river, even though it is geographically nearer the latter. The same pattern emerges from Siqueira Filho’s work on bromeliads.
The 24 new species of bromeliads described by Siqueira Filho over the last ten years hint at the extent of what is still there to be discovered. The same is true of the fauna. In 2006, the blond capuchin monkey drew attention to the northeastern forests: was it a new species of Cebus queirozi or the rediscovery of C. flavius¸ registered for the first time in 1648 and never again seen. However, almost all the species described recently, such as the Pernambuco pigmy owl (Glaucidium mooreorum), in 2002, are already under threat of extinction.

Siqueira Filho fears that the typical northeastern Mata Atlântica forest animals are already as good as lost, but does not hesitate to point out solutions, such as replanting the ciliary forests and establishing reserves in areas near mills. “There are economic opportunities: Europe and the United States have started to demand environmental quality certificates”, he states. His work is improving our understanding of the ecology of the Mata Atlântica rainforest, but for him scientific knowledge can, and should, be the basis of concrete actions.

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