Raimundo Paulo Barros Henriques

Post-fire succession of small mammals in the Cerrado of central Brazil

In the Cerrado savannas from Brazil fire events are common and strongly influence the vegetation structure and, consequently, the associated small mammals. In this paper, we investigate changes in the structure of small mammal communities related to sites of different post-fire ages. Mammals were captured in similar Cerrado sites that differed in time since the last burn (1 to 26 yr). We sampled six sites in the wet season of 1997 (phase 1) and, three years later, six sites in the wet and dry seasons (phase 2). Six rodent species and four marsupials were captured. Community composition changed drastically as a function of time since fire. The diversity and abundance of small mammals reached maximum values in the early successional stages. The rodent Calomys tener was present only in early seral stages. The rodent Bolomys lasiurus was more frequent in mid-successional stages and decreased in later seral stages, and the rodent Oryzomys subflavus occupied all successional stages. The marsupial Gracilinanus agilis was dominant in the area that did not burn for at least 23 yr. Changes in composition of the community of small mammals were more accelerated in early successional stages, when there are more drastic vegetational changes. The ability of small mammals to cope with Cerrado fires and the great dissimilarity among post-burning seral stages suggest that a mosaic of areas representing different post-fire seral stages could increase the regional diversity of this group.

Influência da flora das florestas Amazônica e Atlântica na vegetação do cerrado sensu stricto

The contribution of Amazonian and Atlantic floras was analyzed in twelve localities in the cerrado biome. A total of 290 tree and shrub species were recorded in those localities. Of these, 41.1% occurred only in cerrado and are probably endemic, and 58.9% also occurred in Atlantic and/or Amazonian forest. For non-endemic species the contribution of Atlantic forest was greater (44.8%) than Amazonian ones (1.4%), with the remaining 12.7% species found in both forest biomes. The proportions of species with centers of distribution in Atlantic and Amazonian forest showed a slight decrease toward the center of cerrado biome. For the former, the distance explained only 30% of variation in proportions by a polynomial model fit to the data, and for the latter a significant linear model explained 78% of variations. The flora of Amazon forest and Atlantic forest showed a segregation with altitude. The proportions of species with centers of distribution in the Atlantic forest showed a slight increase with altitude, but a polynomial model explained only 18% of this variation. Inversely, there was a linear relationship between the proportions of species with centers of distribution in Amazonian forest and altitude that explained 31% of variation. The differences in contribution patterns of the Atlantic and Amazonian forest flora to the cerrado physiognomy is discussed with respect to climatic changes during the Quaternary and to differences in plant species tolerance to fire and low temperature in the cerrado biome.

Síndromes de dispersão de espécies arbustivo-arbóreas em cerrado sensu stricto do Brasil Central e savanas amazônicas

O objetivo deste trabalho foi identificar as proporcoes das sindromes de dispersao de sementes em areas de cerrado sensu stricto do Brasil Central, comparando-as com as de areas isoladas de savanas amazonicas. Foram utilizadas listas de especies de nove areas de cerrado e cinco areas de savanas amazonicas. Determinou-se a similaridade floristica entre as areas. As sindromes de dispersao de especies ocorrentes nestas areas foram determinadas a partir de dados da literatura. Utilizou-se o teste Qui-quadrado (c2) a fim de detectar possiveis diferencas nas proporcoes de zoocoria e anemocoria entre as areas de cerrado e entre as areas de savanas amazonicas. As medias entre as duas regioes foram comparadas pelo teste t. Nao foram encontradas diferencas significativas para as duas analises (p > 0,05). A media das proporcoes de zoocoria para o cerrado sensu stricto foi de 56,7% ± 5,4 DP e para as savanas amazonicas 55,6% ± 11,7 DP, e a media das proporcoes de anemocoria no cerrado sensu stricto foi de 39,7% ± 6,2 DP e para as savanas amazonicas 44,4% ± 11,7 DP. No cerrado sensu stricto, a autocoria variou de 1,4 a 5%, porem nao se verificou a presenca de especies autocoricas nas savanas amazonicas. A autocoria e uma estrategia de dispersao raramente encontrada no cerrado e sua ausencia nas areas de savanas amazonicas pode estar relacionada a sua baixa eficiencia em colonizar areas isoladas.

Produção primária líquida em área queimada e não queimada de campo sujo de cerrado (Planaltina - DF)

The above-ground net primary production was estimated for two areas of campo sujo of cerrado, one unburnt and the other initially burnt. Production was estimated by using diferences in the above-ground biomass which was sampled at quarterly intervals. The study was planned to coincide with the wet season, between october 1980 and april 1981. The above-ground net primary production of the herbaceous layer in the burnt area (176 ± 33 g m-2) was higher than in the unburnt area (108 ± 26 g m-2). The efficiency of the conversion of solar energy into dry matter was 0,12 ± 0,0,03% for the unburnt campo sujo and 0,19 ± 0,04% for the burnt campo sujo. The quartely production figures had significative correlation with precipitation and soil water, showing that the water is a limiting factor to the herbaceous layer primary production in campo sujo of cerrado.

Variação espacial e influência do habitat na estrutura de comunidades de pequenos mamíferos em áreas de campo rupestre no Distrito Federal

No presente estudo foram investigadas as comunidades de pequenos mamiferos em campos rupestres do Distrito Federal (DF). Foram analisadas a composicao, abundância e riqueza e suas relacoes com a estrutura do habitat e se existe variacao espacial significativa na composicao de especies entre os sitios de campo rupestre. Os pequenos mamiferos foram estudados com o metodo de marcacao e recaptura em sete sitios. O esforco total para os sete sitios foi de 5.680 armadilhas-noite, sendo capturados 157 individuos e oito especies de roedores. Calomys tener e Cerradomys scotti foram as especies mais abundantes do estudo, com 47,1 e 18,0% do total de individuos, respectivamente. Ambas estavam presentes em todos os sitios amostrados. Os resultados mostraram que as areas de campo rupestre do DF apresentam uma fauna de pequenos mamiferos (media de quatro com amplitude de variacao de tres a cinco especies), comparaveis a de outras fisionomias de Cerrado. A complexidade do habitat mostrou-se como um dos principais determinantes na composicao das comunidades de pequenos mamiferos em campo rupestre. Houve distincao entre as comunidades de pequenos mamiferos dos sitios da APA Gama e Cabeca de Veado e dos sitios da APA de Cafuringa. Foi constatada influencia da distância entre os locais sobre a composicao de especies, com a similaridade diminuindo com o aumento da distância entre os sitios. As diferencas nas condicoes ambientais, na estrutura do habitat e o fato de tratar-se de duas possiveis regioes biogeograficas podem explicar as diferencas faunisticas entre as duas regioes.

Registro de Gracilinanus agilis (Marsupialia, Didelphidae) parasitado por Metacuterebra apicalis (Diptera, Cuterebridae) no cerrado de Brasília, Distrito Federal, Brasil

The first report of infection caused by maggots of the botfly Metacuterebra apicalis (Guerin-Meneville) on miceopossums Gracilinanus agilis (Burmeister) is presented. The examined individuals collected in the cerrado vegetation in Brasilia, DF, Brazil, showed infections in ventral area of the body, around genital organs. Two botflies (male and female) emerged in a period of 29 to 31 days.