Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Avaliação de Três Cultivares de Panicum maximum Jacq. sob Pastejo: Composição Química e Digestibilidade da Forragem Evaluation of Three Cultivars of Panicum Maximum Jacq. under Grazing: Chemical Composition and in Vitro Organic Matter Digestibility

O estudo foi conduzido com o objetivo de estimar o valor nutritivo da MS de três cultivares de Panicum maximum Jacq. submetidas ao pastejo rotativo, através dos teores de proteína bruta, fibra em detergente neutro, fibra em detergente ácido, lignina, celulose, sílica e digestibilidade in vitro da matéria orgânica em amostras de folhas e colmos. Estudou-se, também, no cultivar Tanzânia, a adubação nitrogenada no final do período chuvoso, adicional à de manutenção comum às demais cultivares. As amostragens foram realizadas em junho, setembro e novembro de 1998 e março de 1999. Algumas diferenças entre tratamentos foram observadas, apresentando, em geral, menor valor nutritivo no cv. Massai, com menores teores de proteína bruta e digestibilidade e maiores teores de fibra em detergente neutro, fibra em detergente ácido e lignina tanto nas folhas, como nos colmos. Sua utilização como opção forrageira deve basear-se em outras características agronômicas. O cv. Mombaça apresentou, em geral, maiores teores de sílica e seu valor nutritivo não foi afetado pela adubação nitrogenada no final do período chuvoso, exceto pelo aumento no teor de proteína bruta e pela redução do conteúdo de lignina e sílica em março. O valor nutritivo dos colmos foi inferior ao das folhas. O início do período chuvoso foi, em geral, a época de maior valor nutritivo da forragem em todos os tratamentos.<br>A study was conducted to evaluate three cultivars of Panicum maximum Jacq. under rotational grazing for the nutritive value,where the estimates of crude protein, neutral detergent fiber, acid detergent fiber, lignin, cellulose, silica, and in vitro digestibility of the organic material were performed in samples of leaves and stems. Additional nitrogen was applied in cv. Tanzania at the end of the rainny season. Samples were taken in June, September, and October 1998 and in March 1999. Some differences among treatments were observed. In general, cv. Massai showed a lower nutritive value with lower crude protein and digestibility, and higher neutral detergent fiber, acid detergent fiber, and lignin, either in samples of leaves or in stems. Therefore, its utilization as a forage option should be based on other agronomic characteristics. The cv. Mombaça exhibited higher concentrations of silica and its nutritive value was not affected by nitrogen fertilization at the end of the rainny season, except for an increase in the percentage of crude protein and a reduction in the amount of lignin and silica in March. The nutritive value of the stems was inferior to the leaves. The nutritive value was highest in all treatments at the beginning of the rainny period

Quality of poultry litter submitted to different treatments in five consecutive flocks Qualidade da cama de frango submetida a diferentes tratamentos em cinco lotes consecutivos

It was evaluated the effects of poultry litter treatment on moisture content, pH, density and volatilized ammonia for five consecutive flocks of broiler chicken breeding. It was used 640 birds per flock as a complete randomized design with eight treatments and four replicates. The treatments were the following: 1 non-treated litter; 2 litter submitted to in-house composting; 3 litter treated with aluminum sulfate; 4 litter submitted to gypsum; 5 litter treated with quicklime; 6 litter treated with dolomitic limestone; 7 litter treated with zeolite and 8 litter treated with charcoal. Chopped elephant-grass hay was used as poultry litter in all flocks. Fermentation in the shed increased moisture content of the litters in the second and first flocks on 21 and 42 days of breeding, respectively. There was no difference on density among treatments. Aluminum sulfate reduced pH of the litters in all flocks at 21 days of breding. On 42 days of breeding, pH of the litters was reduced in the litters with aluminum sulfate and gypsum in the first, second and forth flocks. On 21 days, aluminum sulfate reduced the volatilized ammonia in the first, third and forth flocks, and on 42 days, there was a reduction of volatilized ammonia in the litters with aluminum sulfate in the forth flock. Aluminum sulfate can improve quality of poultry litter of chopped elephant-grass hay by reducing pH and ammonia volatilization.<br>Foram avaliados os efeitos do tratamento da cama de frango sobre o teor de umidade, o pH, a densidade e a amônia volatilizada durante cinco lotes consecutivos de criação de frangos de corte. Foram utilizadas 640 aves por lote em delineamento inteiramente casualizado com oito tratamentos e quatro repetições. Os tratamentos foram: 1 cama não-tratada; 2 cama submetida à compostagem dentro do galpão; 3 cama tratada com sulfato de alumínio; 4 cama tratada com gesso agrícola; 5 cama tratada com cal virgem; 6 cama tratada com calcário dolomítico; 7 cama tratada com zeolita; e 8 cama tratada com carvão vegetal. O feno de capim-elefante picado foi utilizado como cama de frango em todos os lotes. A fermentação no galpão aumentou o teor de umidade das camas no segundo e primeiro lotes aos 21 e 42 dias de criação, respectivamente. Não houve diferença na densidade entre os tratamentos. O sulfato de alumínio reduziu o pH das camas em todos os lotes aos 21 dias de criação. Aos 42 dias, o pH das camas foi reduzido nas camas contendo sulfato de alumínio e gesso agrícola no primeiro, segundo e quarto lotes. Aos 21 dias, o sulfato de alumínio reduziu a amônia volatilizada no primeiro, terceiro e quarto lotes e, aos 42 dias, houve redução da amônia volatilizada das camas contendo sulfato de alumínio no quarto lote. O sulfato de alumínio pode melhorar a qualidade da cama de frango de feno de capim-elefante picado, por reduzir o pH e a volatilização de amônia