Seed shadow, seedling recruitment, and spatial distribution of Buchenavia capitata (Combretaceae) in a fragment of the Brazilian Atlantic Forest / Sombra de sementes, recrutamento de plântulas e distribuição espacial de Buchenavia capitata em um fragmento da Floresta Atlântica Brasileira

Here we describe the seed shadow, seedling recruitment, ontogenetic structure and spatial distribution of Buchenavia capitata (an emergent canopy tree) in a 380-ha fragment of the Atlantic forest in northeast Brazil. In particular, we examine seed distribution around 10 parental trees and both seedling recruitment and mortality, during an 18 month period beneath and around parental trees. Moreover, we describe: (1) B. capitata occurrence within treefall gaps; (2) population structure in terms of ontogenetic stages for the whole site; and (3) spatial distribution of adults within an area of 51 hectares. 99 percent of seeds were found beneath parent crowns (n = 4,236) and seed density reached 14.6 ± 29.9 seeds/m² (0-140 seeds/m²). 49 percent of all seeds germinated but seedling mortality reached 100 percent after an 18 month period. In addition, saplings of B. capitata were not found in forest understory and within 30 treefall gaps (94-2,350 m²). The adults showed an average DBH of 69.3 ± 22.1 cm, were 19.2 ± 2.9 m tall and presented a clumped spatial distribution. B. capitata matched some of the features presented by shade intolerant trees or large-gap specialists, and we hypothesize that low rates or even lack of long distance seed dispersal events may be reducing the probability of B. capitata seeds reaching suitable habitats for successful seedling recruitment and growth. Because of that (1) seedlings face high levels of early mortality; (2) there is no sapling recruitment at the study site; and (3) local population faces senility and it is threatened by local extinction.

Neste estudo, são descritas a sombra de sementes, o recrutamento de plântulas, a estrutura ontogenética e a distribuição espacial de Buchenavia capitata (árvore emergente) em um fragmento de 380 ha da floresta Atlântica do Nordeste do Brasil. Particularmente, são examinadas a distribuição de sementes de 10 árvores e o recrutamento e a mortalidade de plântulas durante 18 meses, tanto embaixo quanto em volta dos adultos. Além disso, descrevem-se: (1) a ocorrência de B. capitata em 30 clareiras; (2) a estrutura populacional em termos de estágios ontogenéticos para toda a área; e (3) a distribuição espacial dos adultos dentro de uma área de 51 hectares. Noventa e nove por cento das sementes foram encontradas embaixo das copas das matrizes (n = 4236) e a densidade de sementes alcançou 14,6 ± 29,9 sementes/m² (0-140 sementes/m²). Quarenta e nove por cento de todas as sementes germinaram, mas a mortalidade de plântulas atingiu 100 por cento após 18 meses. Além disso, jovens de B. capitata não foram encontrados no sub-bosque e em 30 clareiras (94-2350 m²). Os adultos mostraram um DAP médio de 69,3 ± 22,1 cm, 19,2 ± 2,9 m de altura e apresentaram uma distribuição espacial agregada. B. capitata apresenta características comuns às árvores intolerantes à sombra ou especialistas de grandes clareiras. Baixas taxas, ou mesmo a ausência, de dispersão de sementes a longa distância podem estar reduzindo a probabilidade de sementes de B. capitata alcançarem hábitats adequados ao recrutamento e ao desenvolvimento das plântulas. Por causa disto (1) as plântulas enfrentam altos níveis de mortalidade; (2) não tem ocorrido recrutamento de jovens; e (3) a população é senil e está ameaçada de extinção local.

Glycosaminoglycan structure and content differ according to the origins of human tumors

The glycosaminoglycans of the tumor mass and from the urine of patients with a nephroblastoma of embryonic origin (Wilms' tumor) and hypernephroma were analyzed. The urine of patients with Wilms/ tumors prior to treatment, and two patients with metastasis contained high levels of hyaluronic acid (2-5 mg/l of urine) when compared to patients after surgery or chemotherapy where the content of hyaluronic acid was less than 0.1 mg/l. Urine of patients with hypernephroma and normal individuals contained even smaller amounts of hyaluronic acid. Normal kidneys contain mainly dermatan sulfate and heparan sulfate, while the hypernephroma and Wilms' tumor contain substantial amounts of chondroitin sulfate. The amount of glycosaminoglycans isolated from Wilms' tumor and hypernephroma were 10 times and 3 times, respectively, greater than normal kidneys. The amonunts of hyaluronic acid in Wilms' tumor varied from 56 to 73 per cent whereas normal kidneys contained about 13 per cent. Chondroitin sulfate was also increased in Wilms' tumor and hypernephroma. It corresponded to 11 per cent and 42 per cent, respectively, of the total glycosaminoglycans. These and other findings indicate that the glycosaminoglycans of Wilms' tumors resemble those present during embryonic development of normal tissues whereas those in hypernephroma are typical of other carinomas of different origins