José Felipe Ribeiro

Analysis of the floristic composition of the Brazilian cerrado vegetation II: Comparison of the woody vegetation of 98 areas

An analysis was made of the floristic composition of 98 areas of cerrado and Amazonian savanna, encompassing most of the area of such vegetation in Brazil. A total of 534 species of trees and large shrubs were recorded for these areas, of which 158 (30%) occurred at a single site only. Such unicates and taxa without determinations to specific level were excluded from the study since they provide no basis for comparison. The data were analysed by three techniques of multivariate analysis: (a) a divisive hierarchical classification by Two-way Indicator Species Analysis (TWINSPAN). (b) an agglomerative hierarchical classification by UPGMA (Unweighted Pair-Groups Method using Arithmetic Averages) using the Sorensen Coefficient of Community (CC) as a measure of similarity, and (c) an ordination by Detrended Correspondence Analysis (DCA). The results from all three methods showed great similarity, demonstrating a strong geographic pattern in the distribution of the flora of the cerrado biome and allowing the recognition of southern (Sâo Paulo and S Minas Gerais), southeastern (largely Minas Gerais), central (Federal District, Goias and parts of Minas Gerais), central-western (largely Mato Grosso, Goias and Mato Grosso do Sul) and northern groups (principally Maranhao, Tocantins and Para), as well as a disjunct group of Amazonian savannas. Soil type (mesotrophic or dystrophic) is an important factor in determining floristic composition. The study demonstrated that cerrado vegetation is extremely heterogeneous: none of the 534 species occurred at all sites and only 28 species were present at 50% or more.

Biogeographic patterns, β-diversity and dominance in the cerrado biome of Brazil

From a total woody flora of ca. 1000 species, a suite of 121 species forms an oligarchy dominating the cerrado biome. This mirrors patterns of dominance described in western Amazonian rain forests. Widespread sampling shows that across the biome this suite of species contributes on average 66% of the total species composition, and 75% of the total Importance Value Index in cerrado communities. An analysis of the floristic similarity between six cerrado phytogeographic provinces (southern, central and south-eastern, central-western, far-western, north-eastern, disjunct Amazonian) reveals great heterogeneity within the biome, principally of the less common species. Of the 951 species recorded from 375 floristic surveys across the biome, 494 species (more than half of the total) are found in only one of the provinces, with very few species (37, i.e., 3.9%) found in all six provinces. Each of the provinces contains a significant number of species which are apparently confined to it, ranging from 15 species (1.6% of the total woody cerrado flora) in the far-western province (primarily in the state of Rondônia) to 162 species (17%) in the central-western province. At the local level, floristic similarity can be very high. An analysis of the floristic composition of 13 sites within the Federal District shows a woody flora of 236 species, indicating that 25% of the total woody flora of the cerrado biome is represented in 0.3% of its area, illustrating the great conservation importance of this region. Floristic similarity between sites within the Federal District is high, although much of this similarity is accounted for by ‘oligarch’ species which account for between 59 and 89% of total species recorded per site. Informed conservation judgements within the cerrado need to take account of regional floristic patterns to ensure maximum protection of biodiversity, as the majority of species are not geographically widespread within the biome.

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.

Aspectos fenológicos de seis espécies vegetais em matas de galeria do Distrito Federal

The phenology of Vochysia piramidalis, Tapirira guianensis, Talauma ovata, Tococa formicaria, Miconia pseudonervosa and Miconia chamissois were observed weekly, from April/94 to September/95, on ten individuals of each specie. All species presented perennial leaves maybe due to soil water availability. According to the beginning of the rainy season, V. piramidalis and T. guianensis presented delayed flowering, T. ovata, T. formicaria and M. pseudonervosa precocious flowering, while M. chamissois was classified as late. Miconia pseudonervosa and T. formicaria showed a long period of flowering and V. piramidalis, T. ovata, T. guianensis and M. chamissois a short one. Vochysia piramidalis showed anemochorous dispersal pattern and all the other five species showed zoochorous. Miconia pseudonervosa showed ripeness varying among and within plant. Talauma ovata also showed a long period of immature fruits, but with simultaneous and quick ripening within the same tree. Tapirira guianensis presented a large period of fruit production, simultaneous ripeness and short intervals between reproductive periods. Tococa formicaria and M. chamissois showed a non-simultaneous short fruiting period within the same tree. In general, the zoocoricous species showed fruiting period within the rainy season, with corresponding animal dispersal period.

Crescimento inicial de Piptadenia gonoacantha (Leguminosae, Mimosoideae) sob inundação em diferentes níveis de luminosidade

This study focus on ecological aspects of flooding on five month old seedlings of Piptadenia gonoacantha, a Gallery forest species. Seedling growth rates were evaluated on three levels of sun light (100%, 70% and 40%) and two soil moisture conditions (field capacity and flooded). Flooding reduced aerial and root growth. There was no interaction between light intensity and flooding, except for foliar dry matter (60 days) and top/root ratio (20 days). Full sun light seedlings under flooding had 67% lower foliar dry matter production than shaded ones, after 60 days. Flooded seedlings in all three light levels, had hypertrophic lenticels on submerged stems, after 20 days. In additon, flooding induced root decomposition but no adventicious roots were observed. After 60 days of flooding, seedlings of P. gonoacantha presented 100 % survival and no significant injury on the top portion.

Dinâmica de populações de espécies lenhosas de Cerrado, Balsas, Maranhão

The objective of the present study was to evaluate the population dynamics of 12 woody species. This study was conducted in two fragments of Cerrado stricto sensu in the Gerais de Balsas Colonization Project, located in Southern Maranhao, Brazil, between 1995 and 2002. The frequency distribution in diameter classes showed the reverse J-shape curve for the majority of species studied. The high recruitment rates were registered for Byrsonima coccolobifolia, Sclerolobium paniculatum e Vochysia rufa, in fragment 1, and B. coccolobifolia, Byrsonima crassa, Davilla elliptica and Qualea parviflora, in fragment 2. The high growth rates were registered for B. crassa, Q. parviflora, S. paniculatum and V. rufa, to both fragments. The species that presented high recruitment and high growth rates, probably, will remain as the principal species in the community structure. On the other hand, the populations of Connarus suberosus, D. elliptica, Hirtella ciliata and Erythroxylum deciduum, in fragment 1, and Salvertia convallariaeodora, in fragment 2, did not present high recruitment rates, in this manner, if the tendencies persist these populations will probably have their survival compromised in the future.

Nurse plant effect of Solanum lycocarpum A. St.-Hil. in area of Brazilian Savanna undergoing a process of restoration

The use of nurse plants in ecological restoration aims to reactivate succession processes to improve environmental quality and biodiversity. This study targets Solanum lycocarpum as a nurse species to promote different plant species beneath its crown by microenvironmental changes in a disturbed area in Brazilian Savanna undergoing a process of restoration. The hypothesis is that S. lycocarpum modifies the microenvironment beneath its crown and influence in order to facilitate the density and richness of different plant species. Biotic parameter as density and species-rich biota, dispersal syndromes and habit were sampled. Additionally abiotic parameters were evaluated: litter thickness, light interception, penetration resistance, moisture, soil bulk density, saturated hydraulic conductivity of soil, nutrient content, acidity and soil structure. These parameters were evaluated in ten sampling units beneath S. lycocarpum, called the area of direct influence, ten around the nurse species crown, in the area of indirect influence and ten in open fields nearby without the influence of other trees, in the control area. For the biotic factors, density and species richness were higher beneath the crown of S. lycocarpum than in other treatments, mainly due to more litter accumulation, light interception, higher nutrient content (potassium, calcium and magnesium), more moisture and lower penetration resistance. Results showed the importance of S. lycocarpum as a nurse species in a Brazilian Savanna area, because of their role in local microenvironmental changes to facilitate other plant species and promote succession processes.

Tree diversity and above-ground biomass in the South America Cerrado biome and their conservation implications

Less than half of the original two million square kilometers of the Cerrado vegetation remains standing, and there are still many uncertainties as to how to conserve and prioritize remaining areas effectively. A key limitation is the continuing lack of geographically-extensive evaluation of ecosystem-level properties across the biome. Here we sought to address this gap by comparing the woody vegetation of the typical cerrado of the Cerrado–Amazonia Transition with that of the core area of the Cerrado in terms of both tree diversity and vegetation biomass. We used 21 one-hectare plots in the transition and 18 in the core to compare key structural parameters (tree height, basal area, and above-ground biomass), and diversity metrics between the regions. We also evaluated the effects of temperature and precipitation on biomass, as well as explored the species diversity versus biomass relationship. We found, for the first time, both that the typical cerrado at the transition holds substantially more biomass than at the core, and that higher temperature and greater precipitation can explain this difference. By contrast, plot-level alpha diversity was almost identical in the two regions. Finally, contrary to some theoretical expectations, we found no positive relationship between species diversity and biomass for the Cerrado woody vegetation. This has implications for the development of effective conservation measures, given that areas with high biomass and importance for the compensation of greenhouse gas emissions are often not those with the greatest diversity.