Plantas terrestres

Plantas terrestres

(Parte 1 de 8)

SECRETARIA DE BIODIVERSIDADE E FLORESTAS DIRETORIA DE CONSERVAÇÃO DA BIODIVERSIDADE PROJETO ESTRATÉGIA NACIONAL DE DIVERSIDADE BIOLÓGICA (BRA 97 G 31)

DIVERSIDADE BIOLÓGICA DO BRASIL COBIO/MMA – GTB/CNPq – NEPAM/UNICAMP

PLANTAS TERRESTRES Versão Preliminar

Índice

1. Introdução 6 2. Briófitas 6 2.1. Diversidade no Brasil e no mundo 7 2.2. Observações sobre subgrupos específicos 8 2.3. Biomas 8 2.4. Regiões 9 2.5. Coleções e infra-estrutura taxonômica 9 2.6. Importância econômica e ecológica 9 2.7. Recursos humanos 10 2.8. Perspectivas e necessidades 10 3. Pteridófitas 12 3.1. Diversidade no Brasil e no mundo 13 3.2. Observações sobre subgrupos específicos 13 3.3. Biomas 14 3.4. Regiões 14 3.5. Coleções e infra-estrutura taxonômica 14 3.6. Importância econômica e ecológica 15 3.7. Recursos humanos 15 3.8. Perspectivas e necessidades 15 4. Gimnospermas 16 4.1. Diversidade no Brasil e no mundo 16 4.2. Observações sobre subgrupos específicos 17 4.3. Biomas 17 4.4. Regiões 17 4.5. Coleções 18 4.6. Importância econômica e ecológica 18 4.7. Recursos humanos 18 4.8. Perspectivas e necessidades 18 5. Angiospermas 19 5.1. Diversidade no Brasil e no Mundo 19 5.2. Observações sobre subgrupos específicos 2 5.3. Biomas 23 5.4. Regiões 24 5.5. Importância econômica e ecológica 24 5.6. Recursos humanos 25 5.7. Perspectivas e necessidades 29 6. Manuais de Identificação 29 7. Coleções e infra-estrutura taxonômica 32 8. Métodos de trabalho 45 9. Considerações finais 46 10. Referência Bibliográficas 47 1. Apêndice 1 50 12. Apéndice 2 5 13. Apêndice 3 58 14. Apêndice 4 57 15. Apêndice 5 58

Summary

– 20% of the known speciesThis represents a substantial fraction of our globe’s total biodiversity and gives

From the viewpoint of terrestrial plants, Brazil is the most biodiverse country in the world and contains from 15 Brazil both a privileged position and a heavy responsibility in the exploration, exploitation and preservation of word biodiversity. This report discusses what is known about this diversity and attempts to evaluate capacity to deal with it in terms of manpower and infrastructure. Terrestrial plants are treated here as four major groups – Bryophytes, Pteridophytes, Gymnosperms and Angiosperms.

The Bryophytes are relatively small, delicate, plants and are represented in Brazil by about 3,100 species – about 2% of the total species known. The country thus possesses a very high proportion of the world bryophyte flora. The number of professional or serious amateur bryologists in Brazil is very limited, with perhaps only 9 or 10 researchers in permanent positions. Although the total number of species can be estimated, bryophyte collections for Brazil are still very limited and a sizeable proportion, including most of the type material essential for nomenclatural studies and taxonomic revisions, are deposited in herbaria in Europe or the U.S..A. Knowledge of regional distributions and occurrence of species in the major biomes is still very incomplete and it is not possible to give accurate data. It is clear, however, that the major regions of bryophyte diversity are in the South and Southeast of Brazil and not in the lowland Amazonian regions which tend to be comparatively poor in bryophytes. At present, the bryologists working in Brazil are capable of identifying much of the material collected in the country, but their limited numbers make it difficult to deal with the demand for identifications as well as carrying out original taxonomic research. Although this group is not of great economic importance, it is of considerable interest from an ecological and evolutionary viewpoint. Major recommendations for this group include : ¾ An increase in the total number of researchers working with the group

¾ Formation of new researchers can be partially completed within Brazil, but the number of potential supervisors is very limited and it may be necessary to send students for overseas training, especially where a recognised expert is available to supervise. ¾ Considerable investment in new collections and studies of geographical distributions is required

¾ Conservation of these organisms depends on the conservation of entire habitats, especially forests, since live collections and storage of spores are not viable options for conservation

The Pteridophytes are a group of larger, vascular plants which, like bryophytes, reproduce by spores and prefer relatively humid, shady habitats. This group is rather less diverse in Brazil, with perhaps about 1,400 species, representing about 10-12% of the world total. The number of researchers working on Pteridophytes in Brazil is also very low. The estimate of overall diversity is probably reasonably accurate, but there are still great taxonomic difficulties with some groups. Knowledge of regional distribution and occurrence in different biomes is somewhat better that that for bryophytes, but still very limited. Like the bryophytes, greatest diversity is found in the South and Southeast of the country and not in the lowland Amazonian forests which tend to be relatively poor in species. Pteridologists working in Brazil are capable of identifying the majority of material found within the country, but once again, tend to be overwhelmed by the quantity of material to be identified and the number of groups still requiring taxonomic revision. Although this group is of limited economic importance (mainly ornamental plants), it is of considerable interest from an ecological and evolutionary viewpoint. Major recommendations : ¾ An increase in the total number of researchers working with the group

¾ Formation of new researchers can be probably mainly be completed within Brazil, but the number of potential supervisors is very limited and it may be necessary to send students for overseas training, especially where a recognised expert is available to supervise. ¾ Considerable investment in new collections and studies of geographical distributions is required

¾ Conservation of these organisms depends on the conservation of entire habitats, especially forests.

Although some ferns are commonly cultivated, there are no comprehensive live collections and some of the other groups of pteridophytes are more difficult to cultivate. Spore storage is probably not a viable option.

The Gymnosperms are a predominantly woody group, with most species forming moderate or large trees. There are probably only 14-16 species of Gymnosperms in Brazil, representing only about 2% of the world total. This is not surprising since the group is commonest in cold-temperate climates. There appear to be no Brazilian specialists working exclusively with this group, but most of the species can be identified without great difficulty, except for the genus Gnetum in the Amazonian area. Economic value is chiefly confined to Araucaria (wood) and Ephedra (ephedrine production), but the genera Gnetum, Ephedra and Zamia are of great interest from an evolutionary point of view. Main recommendations : ¾ Training and formation of specialists in taxonomy of the group is probably not justified, given the small number of species, but investigation of genetic variation and preservation of germplasm of natural populations of Araucaria should receive some priority.

¾ Strong efforts should be made to investigate the ecology and reproductive biology of Gnetum, Zamia and

Ephedra to ensure adequate protection for natural populations of these genera, given their great evolutionary significance and relative rarity world-wide.

plantsNo recent floras or identification manuals are available for the whole of the Brazilian flora and it is

The Angiosperms (flowering plants) are by far the most abundant and dominant of all the terrestrial plants. The Brazilian flora probably contains about 50,0 or more species, representing about 16-20% of the world total. There are probably around 200 researchers in Brazil working actively with the taxonomy and identification of this group of plants, with a further group capable of identifying at least commoner species, and other researchers working with ecology, reproductive biology, cytology and genetic variation. Although this number of researchers is impressive when compared with those working with other groups, they are far from sufficient in the face of the large size of this group and the overwhelming economic and ecological importance of these unlikely that such an undertaking can be contemplated in the immediate future. For the moment, a strategy of developing floras at state level or more restricted areas seems to be a consensus among researchers in Brazil, and attempts to produce a complete flora would require a huge expenditure of time and effort which is simply not feasible at present. Knowledge of geographical and ecological distribution is much more abundant than in other groups but is not available in a concentrated and systematic form, and it is difficult to give accurate data for regional and biome-level diversity. Major recommendations for this group are : ¾ An increase in the number of researchers working in the group is highly necessary. Many large families have very few taxonomists or researchers capable of identifying them with any certainty.

¾ Although this group has been more heavily collected than any other group of terrestrial plants, collections are still manifestly inadequate to estimate total floras and regional or local biodiversity. Much effort needs to be expended on improving existing collections and their preservation and in improving the distribution of collections which are still grossly uneven in many regions.

¾ Support should be given to flora projects at state and local level, but the total number of taxonomists available is insufficient to permit simultaneous execution of all flora projects now being planned.

A number of recommendations are equally applicable to all of the groups considered up to now :- ¾ Investment in formation of human resources is highly necessary if Brazil is ever to become reasonably selfsufficient in managing and identifying its own biodiversity. For many groups, especially in the Amazonian region, the only taxonomists capable of identifying to species level live and work in Europe or the US, and only visit Brazil sporadically.

¾ Training and development of new techniques to speed taxonomic and floristic studies should be a high priority. The use of computerised methods for taxonomic description and identification show enormous promise, but require a massive investment in training and resources to succeed.

¾ A large investment in physical infrastructure and informatization of collections is necessary if these are to adequately serve their purpose of documenting biodiversity and as research instruments. Much of the information required for current decisions on biodiversity management and exploitation can probably only be obtained by an extensive and urgent program of databasing of herbaria and other collections.

¾ Progress in taxonomy and ecology for many groups depends on the availability of identification manuals.

Materials suitable for teaching at undergraduate and post-graduate level are almost non-existent for many groups and production of such manuals should be give high priority. Elaboration of well-illustrated, interactive, computerised identification keys could be of great use in teaching and training and should be encouraged.

¾ Repatriation of data and images of type specimens and other materials held in herbaria and other collections abroad would be enormously useful in speeding and facilitating taxonomic research in Brazilian plants. Consideration should be given to establishing a national effort to remedy the lack of such materials and to make them widely available through the internet or on electronic media such as CD-ROMS

¾ The distribution of researchers and collections throughout the country is very uneven, with a great concentration of workers in the Southeast and South. A strong effort is required to increase the number of taxonomists and ecologists working in hyperdiverse regions such as the Amazon basin and Centre-West region.

¾ The use of molecular techniques in plant systematics is currently “fashionable” and of great importance and needs to be further developed in Brazil, but this should not divert efforts and resources from more basic activities of collecting and alpha taxonomy, which form the basis for all other biodiversity studies and supply the raw materials for more sophisticated applications.

1. Introdução

Neste texto, as plantas terrestres serão tratadas como quatro grandes grupos - Briófitas,

Pteridófitas, Gimnospermas e Angiospermas, tradicionalmente considerados filos (ou divisões). Alguns autores mais recentes tendem a dividir estas plantas em pelo menos 12 subfilos ou filos diferentes (com diversos nomes usados):

- Angiospermas - Magnoliophyta - Gimnospermas - Coniferophyta, Cycadophyta, Ginkgophyta, Gnetophyta

- Pteridófitas - Sphenophyta, Psilophyta, Lycopodophyta, Filicinophyta

- Briófitas - Anthocerophyta, Hepatophyta, Bryophyta

Recentes estudos com seqüências de genes sugerem que uma série de reajustes é necessária, mas a situação destes grandes grupos ainda é confusa. Optamos, portanto, por utilizar as divisões mais antigas, por serem mais convenientes e bem conhecidas, até que haja um consenso sobre os nomes e níveis dos grupos superiores de plantas terrestres.

Entre estas plantas, as Angiospermas são as mais numerosas, mais conhecidas e economicamente mais importantes. São as plantas que dominam praticamente todos os ecossistemas terrestres e, com raras exceções, formam a maior parte da biomassa destes sistemas. Também este grupo reúne o maior número de especialistas em taxonomia, ecologia e fisiologia. Os outros três grupos são bem menores, menos abundantes e geralmente economicamente menos importantes, embora as Gimnospermas sejam de grande valor como fonte de madeira.

2. Briófitas

As briófitas são um grupo de plantas relativamente pequenas e delicadas que tendem a preferir ambientes úmidos e sombreados. Tipicamente são epífitas ou formam pequenas touceiras ou camadas finas na superfície do solo e raramente atingem tamanhos além de alguns centímetros de altura (max. 40 cm). Possuem um ciclo de vida com duas fases distintas - o gametófito e o esporófito - onde, ao contrário das outras plantas terrestres, o gametófito haplóide é dominante. Três classes são reconhecidas tradicionalmente - Anthocerotae, Hepaticae e Musci, mas a maioria das classificações recentes trata estes grupos como três filos - Anthocerophyta, Hepatophyta e Bryophyta.

Figura 2.1 Uma hepática – Lophocolea sp.

Figura 2.1 incluir

As relações filogenéticas entre estes grupos são obscuras e talvez não sejam muito próximos. Dados recentes de seqüências genéticas sugerem que um realinhamento destes grupos seja necessário, com parte das hepáticas mais próxima aos musgos do que as restantes. Face à incerteza no nível e subdivisão apropriados para os subgrupos, no resto deste texto optamos por manter o uso das classes tradicionais.

As briófitas geralmente são descritas como plantas avasculares, mas pelo menos algumas espécies têm tecidos condutores no caule, embora não sejam idênticos em estrutura aos tecidos condutores de plantas vasculares.

(Parte 1 de 8)

Comentários