Lognormal abundance distribution of woody species in a cerrado fragment (São Carlos, southeastern Brazil)

Abstract

-(Lognormal abundance distribution of woody species in a cerrado fragment (São Carlos, southeastern Brazil)). The lognormal distribution model is frequently found in communities, especially those which are rich in species and influenced by many environmental factors, as those of the cerrado. We tested the hypothesis that the abundance distribution of woody plant species in a cerrado fragment fits the lognormal model. We placed 20 lines in a cerrado fragment and sampled, with the point-quarter method, 800 individuals with stem perimeter equal or larger than 3 cm. We plotted the abundance-class histogram of the species, verified its normality with the Kolmogorov-Smirnov test, and estimated the expected number of woody species for this community. Of the 63 obtained species, Anadenanthera falcata (with 185 species), Eriotheca gracilipes (43), Stryphnodendron obovatum (37), and Miconia albicans (36) were the most abundant ones. Twelve species were represented by only one individual. We did not reject the null hypotheses that the distribution of woody component species was normal and, thus, their abundances fitted the lognormal model. Therefore, with our work, we can predict that cerrado plant communities fit the lognormal model. If this pattern is maintained in other cerrado communities, there would be implications for the conservation of this vegetation type, because rare species are susceptible of extinction, and implications to their structure, because the dominant species may act as keystone species.Key words -abundance, cerrado, lognormal distribution, savanna RESUMO -(Distribuição normal-logarítmica de espécies arbustivo-arbóreas em um fragmento de cerrado (São Carlos, Sudeste do Brasil)). O modelo normal-logarítmico é freqüentemente encontrado em comunidades, sobretudo naquelas ricas e determinadas por vários fatores ambientais, como o são as comunidades vegetais de cerrado. Testamos a hipótese de que a distribuição de abundância das espécies arbustivo-arbóreas em uma comunidade vegetal de cerrado sensu stricto se ajusta ao modelo normallogarítmico. Para isso, lançamos 20 linhas em um fragmento de cerrado, nas quais amostramos 800 indivíduos arbustivoarbóreos pelo método de quadrantes. Construímos o histograma da distribuição das freqüências das espécies, verificamos sua normalidade com o teste Kolmogorov-Smirnov e estimamos o número esperado de espécies arbustivo-arbóreas para a comunidade. Das 63 espécies encontradas, Anadenanthera falcata (com 185 indivíduos), Eriotheca gracilipes (43), Stryphnodendron obovatum (37) e Miconia albicans (36) foram as mais abundantes. Doze espécies foram representadas por um único indivíduo. Não rejeitamos a hipótese nula de que a distribuição de espécies arbustivo-arbóreas foi normal e, portanto, suas abundâncias se ajustaram ao modelo normal-logarítmico. Dessa forma, com nosso trabalho, podemos prever que comunidades vegetais de cerrado se ajustam ao modelo normal-logarítmico. Se, de fato, esse padrão se mantiver em outras comunidades de cerrado, existirão implicaçõ...

Frugivory by birds on Miconia albicans (MELASTOMATACEAE), in a fragment of cerrado in São Carlos, southeastern Brazil

“…Fruit richness in the period and the high abundance of M. albicans in the studied area (Oliveira and Batalha, 2005) may be an explanation for the low frequency of visits observed for M. albicans. In comparison to data from the abovementioned literature, M. albicans showed from similar to a 3 times lower frequency of bird visits, while the number of observed species could be considered high (in a range of 11 species for R. lancifolia to 20 for P. glabrata).…”

“…In research performed with woody species in the area, M. albicans appears as the fourth most abundant species (Oliveira and Batalha, 2005). Since each treelet has a huge number of flower buds, flowers and/or fruits, it was necessary to estimate the total from an average of direct counting on three inflorescences per individual.…”

Anurans of a riparian forest in Sao Carlos, state of Sao Paulo, Brazil

“…The Cerrado fragment at the Universidade Federal de São Carlos is relatively well known in terms of flora (see Oliveira & Batalha 2005, Valenti et al 2008) and fauna (see Roque et al 2003, Motta-Júnior 2006, Silva et al 2008). However, no study has surveyed the local anuran fauna.…”

Phenology and frugivory by birds on Miconia ligustroides (MELASTOMATACEAE) in a fragment of cerrado, southeastern Brazil

“…Miconia ligustroides is a common, but not abundant species in this area (Oliveira and Batalha, 2005). Its phenophases (see Figure 1) were accompanied in 30 random selected individuals, every two weeks, between March, 2008 andFebruary, 2009.…”