RESUMO

Abstract The Atlantic Forest and Cerrado (Brazilian Savannah) contain a large number of endemic species and high species diversity, particularly for medium and large-bodied mammals. However, there is no large-scale assessment of these animals and their spatial distribution. Our study synthesises the literature on medium and large-bodied mammal surveys in the Cerrado and Atlantic Forest to provide insights into their distributions across large spatial scales and identify knowledge gaps to guide future research. We synthesised papers published in three databases, focusing on mammals weighing more than 1kg. Of the 84 papers we found, the majority (57.14%) were on mammals in the Atlantic Forest, while 42.85% were on mammals found in the Cerrado. We gathered records for 116 species, the most common of which were Cerdocyon thous (Linnaeus, 1766), Procyon cancrivorus (Cuvier, 1798) and Chrysocyon brachyurus (Illiger, 1815) (Cerrado); Dasypus novemcinctus (Linnaeus, 1758), Cerdocyon thous (Linnaeus, 1766) and Nasua nasua (Linnaeus, 1766; Atlantic Forest). Our study allowed us to access, for the first time in the Atlantic Forest and Cerrado, the information available about medium and large-bodied mammals. We also highlight important sampling gaps, especially concerning the northern parts of both biomes that we need to address, as well as the differences in density of sampling points that are caused by a smaller concentration of sampling efforts in the Atlantic Forest than what we found in Cerrado. As a consequence, larger extensions of Cerrado present knowledge gaps concerning mammal surveys that need to be investigated in future research.

Resumo A Mata Atlântica e o Cerrado brasileiro abrigam uma enorme quantidade de espécies endêmicas e alta diversidade de espécies, especialmente de mamíferos de médio e grande porte. No entanto, não há uma avaliação em larga escala desses animais e de sua distribuição espacial. Nosso estudo sintetiza a literatura sobre levantamentos de mamíferos de médio e grande porte no Cerrado e na Mata Atlântica, com o objetivo de fornecer informações sobre suas distribuições em larga escala e identificar lacunas no conhecimento para guiar futuras pesquisas. Sintetizamos artigos publicados em três bases de dados, com foco em mamíferos com peso superior a 1 kg. Dos 84 artigos encontrados, a maioria (57,14%) tratava de mamíferos na Mata Atlântica, enquanto 42,85% abordavam mamíferos encontrados no Cerrado. Coletamos registros para 116 espécies, sendo as mais comuns Cerdocyon thous (Linnaeus, 1766), Procyon cancrivorus (Cuvier, 1798) e Chrysocyon brachyurus (Illiger, 1815) (Cerrado); Dasypus novemcinctus (Linnaeus, 1758), Cerdocyon thous (Linnaeus, 1766) e Nasua nasua (Linnaeus, 1766; Mata Atlântica). Nosso estudo também mostra as lacunas no levantamento especialmente em relação às distribuições ao norte dos biomas, que precisam ser resolvidas, assim como a diferença na densidade de pontos que é causada pela menor concentração de amostragens na Mata Atlântica do que o que encontramos no Cerrado. Como consequência, existem largas extensões do Cerrado que apresentam lacunas no levantamento de mamíferos que precisam ser investigados em pesquisas futuras.

RESUMO

Human activities pose a major threat to tropical forest biodiversity and ecosystem services. Although the impacts of deforestation are well studied, multiple land-use and land-cover transitions (LULCTs) occur in tropical landscapes, and we do not know how LULCTs differ in their rates or impacts on key ecosystem components. Here, we quantified the impacts of 18 LULCTs on three ecosystem components (biodiversity, carbon, and soil), based on 18 variables collected from 310 sites in the Brazilian Amazon. Across all LULCTs, biodiversity was the most affected ecosystem component, followed by carbon stocks, but the magnitude of change differed widely among LULCTs and individual variables. Forest clearance for pasture was the most prevalent and high-impact transition, but we also identified other LULCTs with high impact but lower prevalence (e.g., forest to agriculture). Our study demonstrates the importance of considering multiple ecosystem components and LULCTs to understand the consequences of human activities in tropical landscapes.

Assuntos

RESUMO

Tropical forests on upland soils are assumed to be a methane (CH4 ) sink and a weak source of nitrous oxide (N2 O), but studies of wetland forests have demonstrated that tree stems can be a substantial source of CH4 , and recent evidence from temperate woodlands suggests that tree stems can also emit N2 O. Here, we measured CH4 and N2 O fluxes from the soil and from tree stems in a semi-evergreen tropical forest on upland soil. To examine the influence of seasonality, soil abiotic conditions and substrate availability (litter inputs) on trace greenhouse gas (GHG) fluxes, we conducted our study during the transition from the dry to the wet season in a long-term litter manipulation experiment in Panama, Central America. Trace GHG fluxes were measured from individual stem bases of two common tree species and from soils beneath the same trees. Soil CH4 fluxes varied from uptake in the dry season to minor emissions in the wet season. Soil N2 O fluxes were negligible during the dry season but increased markedly after the start of the wet season. By contrast, tree stem bases emitted CH4 and N2 O throughout the study. Although we observed no clear effect of litter manipulation on trace GHG fluxes, tree species and litter treatments interacted to influence CH4 fluxes from stems and N2 O fluxes from stems and soil, indicating complex relationships between tree species traits and decomposition processes that can influence trace GHG dynamics. Collectively, our results show that tropical trees can act as conduits for trace GHGs that most likely originate from deeper soil horizons, even when they are growing on upland soils. Coupled with the finding that the soils may be a weaker sink for CH4 than previously thought, our research highlights the need to reappraise trace gas budgets in tropical forests.

Assuntos

RESUMO

Improved understanding of the nutritional ecology of arbuscular mycorrhizal (AM) fungi is important in understanding how tropical forests maintain high productivity on low-fertility soils. Relatively little is known about how AM fungi will respond to changes in nutrient inputs in tropical forests, which hampers our ability to assess how forest productivity will be influenced by anthropogenic change. Here we assessed the influence of long-term inorganic and organic nutrient additions and nutrient depletion on AM fungi, using two adjacent experiments in a lowland tropical forest in Panama. We characterised AM fungal communities in soil and roots using 454-pyrosequencing, and quantified AM fungal abundance using microscopy and a lipid biomarker. Phosphorus and nitrogen addition reduced the abundance of AM fungi to a similar extent, but affected community composition in different ways. Nutrient depletion (removal of leaf litter) had a pronounced effect on AM fungal community composition, affecting nearly as many OTUs as phosphorus addition. The addition of nutrients in organic form (leaf litter) had little effect on any AM fungal parameter. Soil AM fungal communities responded more strongly to changes in nutrient availability than communities in roots. This suggests that the 'dual niches' of AM fungi in soil versus roots are structured to different degrees by abiotic environmental filters, and biotic filters imposed by the plant host. Our findings indicate that AM fungal communities are fine-tuned to nutrient regimes, and support future studies aiming to link AM fungal community dynamics with ecosystem function.

Assuntos

RESUMO

We maintained a factorial nitrogen (N), phosphorus (P), and potassium (K) addition experiment for 11 years in a humid lowland forest growing on a relatively fertile soil in Panama to evaluate potential nutrient limitation of tree growth rates, fine-litter production, and fine-root biomass. We replicated the eight factorial treatments four times using 32 plots of 40 x 40 m each. The addition of K was associated with significant decreases in stand-level fine-root biomass and, in a companion study of seedlings, decreases in allocation to roots and increases in height growth rates. The addition of K and N together was associated with significant increases in growth rates of saplings and poles (1-10 cm in diameter at breast height) and a further marginally significant decrease in stand-level fine-root biomass. The addition of P was associated with a marginally significant (P = 0.058) increase in fine-litter production that was consistent across all litter fractions. Our experiment provides evidence that N, P, and K all limit forest plants growing on a relatively fertile soil in the lowland tropics, with the strongest evidence for limitation by K among seedlings, saplings, and poles.

Assuntos