Mesoscale gradients of herb richness and abundance in central Amazonia

摘要: There are few hypotheses to explain local understory diversity patterns. is a consensus that climate and soil fertility affect density at large scales, but studies addressed the mechanisms controlling locally. Here, I examine patterns of abundance three herb groups along gradients nutrients topography mesoscale (64 km2) in wet tropical forest, possible factors causing them. Herb richness, diversity, density, cover were measured fifty-nine 250 × 2 m plots systematically distributed over Reserva Ducke, Manaus. responded differently environmental gradients. Whereas pteridophytes increased with altitude slope, Marantaceae decreased. Density sedges altitude, did not vary slope. cation content. Pteridophyte richness slope whereas decreased, both Diversity for decreased pteridophytes. Some these agree what expected from herbs, such as greater flat low plots, where water availability higher probably also light, nutrient plots. The unexpected results slopes, instead bottomlands, suggest biotic or litter-mediated controls may be important set patterns. RESUMO Existem poucas hipoteses para explicar os padroes locais de diversidade do sub-bosque. Existe consenso que clima e fertilidade solo afetam densidade sub-bosque em macro-escala, mas poucos estudos procuraram mecanismos controlam escala local. Neste estudo, eu examino abundância 3 grupos ervas ao longo nutrientes topografia uma floresta umida, possiveis fatores causais. A riqueza, diversidade, cobertura das foram medidas 59 parcelas m, distribuidas sobre 64 km2 na Os responderam forma diferente aos gradientes ambientais. Enquanto samambaias aumentaram com inclinacao terreno, diminuiram. capins aumentou coma nao variou inclinacao. o conteudo solo, pteridofitas. riqueza terreno enquanto decresceu, dos dois nutrientes. diminuiu samambaias. Alguns destes concordam esperado ervas, tais como maior nas planas baixas, onde disponibilidade agua provavelmente luz sao maiores. Entretanto, resultados inesperados pteridofitas nos terrenos mais inclinados, inves baixios, sugerem controles bioticos ou mediados pela liteira podem ser importantes estabelecimento padroes.