Luiz Fernando D. de Moraes,
Cintia Luchiari, José Maria Assumpção
& Tânia Sampaio Pereira
One of the worlds most threatened ecosystem is the Brazilian Atlantic Rain Forest, which has been deforestated since Brazils discovery (Guedes-Bruni,1998). This forest covers the mountains and lowlands alongside the Brazilian coast, so called Mata Atlântica, which remnant vegetation is today about 6% of its original forest. (Lima & Guedes-Bruni, 1997). Besides the genetic and biodiversity losses, another negative consequence of Atlantic Rain Forest deforestation has been soil erosion.
The urban development along the Brazilian coast left us a legacy of floristic and genetic poverty of our formerly rich forests. The power of typical rain flow from highlands to lowlands caused drastic harms to the soil, leaking its fertility in dangerous erosive processes.
Rio de Janeiro Botanic Garden Research Institute is in charge of studding Rio de Janeiro forest remains and indicate effective conservation strategies for those remnant vegetation.
The Rio de Janeiro Botanic Gardens researchers, concerned about this situation, performed floristic surveys on legally protected remnant forests in Rio de Janeiro State. Our findings indicate that the Poço das Antas Biological Reserve (created to protect the endangered Golden Lion Tamarin - Leonthoptecus rosalia), located in the lowlands, shows the highest plant species diversity (Guedes-Bruni,1998), among the four sites studied along the past 10 years.
Its area is of 5.160 hectares, located on 22° 29 and 22° 36 S and 42°13 and 42° 21 W G, in a very typical Atlantic Tropic Rain Forest, where the annual rainfall is 1.700 mm/year. Average temperature is 24°C. The wetlands represents 60% of the whole area and drylands, 40%.
If community development is high predictable, it may be feasible to manipulate natural succession processes to accelerate forest regeneration (Palmer et al, 1997).The Poço das Antas Reserve vegetation is formed by secondary forests patches surrounded by abandoned pastures (Figure 1). Since the frequent occurrence of fires prevent natural regeneration establishment, the RJBG created a Project to restore those disturbed areas, allowing fire and soil erosion control by forested areas expansion.
Successional models are used to predict how restoration projects can achieve their goals. Those models consist of mixed plantations based on the species ecological features, allowing the site to become self-sustainable (Parker, 1997). The recovery of natural systems by taking the system itself as a reference is called Ecological Restoration.
The first step was to identify which species could be found in natural regeneration sites; secondly , how to produce seedlings of such species. As a matter of fact, the management of most of our natural systems is unknown (Palmer et al. 1997). According to those authors, the science of ecological restoration - that is, the development and testing of a body of theory for repairing damage ecosystems - is in its infancy. However, particularly for this endangered ecosystem, any conservation action is welcome.
It is also known that basic knowledge is required to achieve conservation goals. Based on this statement, the centennial RJBG researchers used their strong background in plant taxonomy to provide a list of species by performing a floristic survey at the Reserve. This list firstly guided species selection, which was also based on their competitivity with the exotic invasive plants. Moreafter, information about secondary succession, plant-animal interactions and trees phenology (Costa et al., 1997) are required.
For conservation purposes, seeds collection for seedlings production is performed using an effective population size (Ne=50). Seeds are collected from 12 (N=12) distant individual trees. Part of the seeds was used for seed germination analysis at the seed laboratory, in order to support seed storage. Different temperatures were tested in order to establish the best temperature for seed analysis in a range of 22 local native species.
The concept for use of the local species were to observe natural regeneration at the two basic landscape situations found at the Reserve: the wetlands (temporarily or permanently floodable plain sites) and drylands (represented by hills reaching up to 100m high) (Figure 3). The first mixed plantation was installed in a wetland site, using early species (pioneer and secondary ones) commonly growing at this site (Figure 2). Species are selected according to their fitness to each situation. A long-term annual monitoring for the plantations is intended.
Results of survival and growth for the species used in both plantings sites (Table 1) showed that the model used for Atlantic Rain Forest restoration was successful and could be used for other similar sites. Another important result was to reduce the plantation maintainance (weed control) period from two years (for the earlier plots) to one year in the latter ones, particularly by selecting species which allowed that, by providing fast soil covering.
After three years, we have very positive overbalance for all the Institutions involved; for both the Reserve, which had some areas reforestated and the Rio de Janeiro Botanic Garden Research Institute, which got a well qualified researchers team in restoration ecology. This research program principles are clearly part of BGCI integrated conservation strategies (1995). Thereafter we can assume we are following the letter of the Botanic Gardens Conservation Strategy (RJBG, 1990) and the agreement of the Convention on Biological Diversity. (Glowka et al, 1994).
Our experience could be used as a model for in-situ conservation in any other similar system, for example the Tijuca National Park, a urban forest in Rio de Janeiro City, which has been threatened by frequent forest sliding and disorded urban occupation. The main RJBG role will be to indicate the most adequate species for mixed plantation models. Thereafter we can assume we are following the letter of the Botanic Gardens Conservation Strategy (RJBG, 1990) and the agreement of the Convention on Biological Diversity. (Glowka et al, 1994).
Fragmented landscape at Poço das Antas Biological Reserve with patched islands of secondary vegetation surrounded by a matrix of aggressive weed forage.
Species used for the plantations at Poço das Antas Biological Reserve, Rio de Janeiro, Brazil.
|Non-pioneers Guarea guidonea||93||2.45||1.29|
|Copaifera langsdorfii||86||0.76 *||0.66 *|
|Calophyllum brasiliensis||84||1.13 *||0.55 *|
Mixed native species scheme for plantation at Poço das Antas Biological Reserve, Rio de Janeiro, Brazil
Wetland plantation (left) and dryland plantation (right) at Poço das Antas Biological Reserve, Rio de Janeiro, Brazil.
Glowka, L. Burhenne-Guilmin,F. , Synge, H., McNeely, J.A. and Gündling, L. (1994). A guide to the Convention on Biological Diversity. Environmental Policy and Law Paper 30. Gland, IUCN, p.15-51.
Jardim Botânico do Rio de Janeiro(JBRJ).(1990). Estratégia dos Jardins Botânicos para a Conservação.Rio de Janeiro. BGCI/ WWF/IUCN 68 pp.
Guedes-Bruni, R.R. (1998). Composição, estrutura e similaridade florística de dossel em seis unidades fisionômicas de Mata Atlântica no Rio de Janeiro.USP, São Paulo, 175pp. PhD thesis.
Lima, H.C. de & Guedes-Bruni, R.R. 1997. Serra de Macaé de Cima: Diversidade Florística e Conservação em Mata Atlântica. Rio de Janeiro. Jardim Botânico do Rio de Janeiro.p. 13 -39.
Palmer, M.A. (1997). Ecological theory and community restoration ecology. Restoration Ecology 5(4):291-300.
Parker, V.T. (1997). The scale of successional models and restoration objectives. Restoration Ecology 5(4): 301-306.
Copyright 1999 NBI