This study investigated changes in diversity of shrub-tree layer, leaf decomposition rates, nutrient release and soil NO fluxes of a Brazilian savanna (cerrado sensu stricto) under N, P and N plus P additions. Simultaneous addition of N and P affected density, dominance, richness and diversity patterns more significantly than addition of N or P separately. Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. The results indicate that if the availability of P is not increased proportionally to the availability of N, the losses of N are intensified.
Cerrado is the second largest biome in South America and accounted for the second largest contribution to carbon emissions in Brazil for the last 10 years, mainly due to land-use changes. It comprises approximately 2 million km2 and is divided into 22 ecoregions, based on environmental conditions and vegetation. The most dominant vegetation type is cerrado sensu stricto (cerrado ss), a savanna woodland. Quantifying variation of biomass density of this vegetation is crucial for climate change mitigation policies. Integrating remote sensing data with adequate allometric equations and field-based data sets can provide large-scale estimates of biomass. We developed individual-tree aboveground biomass (AGB) allometric models to compare different regression techniques and explanatory variables. We applied the model with the strongest fit to a comprehensive ground-based data set (77 sites, 893 plots, and 95,484 trees) to describe AGB density variation of cerrado ss. We also investigated the influence of physiographic and climatological variables on AGB density; this analysis was restricted to 68 sites because eight sites could not be classified into a specific ecoregion, and one site had no soil texture data. In addition, we developed two models to estimate plot AGB density based on plot basal area. Our data show that for individual-tree AGB models a) log-log linear models provided better estimates than nonlinear power models; b) including species as a random effect improved model fit; c) diameter at 30 cm above ground was a reliable predictor for individual-tree AGB, and although height significantly improved model fit, species wood density did not. Mean tree AGB density in cerrado ss was 22.9 tons ha-1 (95% confidence interval = ± 2.2) and varied widely between ecoregions (8.8 to 42.2 tons ha-1), within ecoregions (e.g. 4.8 to 39.5 tons ha-1), and even within sites (24.3 to 69.9 tons ha-1). Biomass density tended to be higher in sites close to the Amazon. Ecoregion explained 42% of biomass variation between the 68 sites (P < 0.01) and shows strong potential as a parameter for classifying regional biomass variation in the Cerrado.
<p>Coffee has major importance in tropical landscapes from agronomic, economic and ecological perspectives. Yet the conversion of shade-coffee into full sun monocultures has deep effect on the potential of those systems to conserve biodiversity and ecosystems services (such as pest control and pollination). Despite of this, effect of shade on production has not been sufficiently addressed, particularly in Brazil, the world major coffee producer. This study compared the performance of shaded coffee and full sun management in terms of productivity and production costs. The survey was conducted in Municipality of Mirante da Serra, in the Brazilian Amazon and eight coffee agroecosystems, four under shade and four under full sun were investigated. The results indicate that shaded systems have lower production costs requiring less working hours than sun plantations. The average production cost of shaded agroecosystems was 49.63%, while in systems under full sun, this value was 82.2%. Shaded and full sun productivity did not differ significantly, with higher variance in the former, showing that shaded systems are more heterogeneous. Shaded coffee agroecosystems presented an economically and environmentally viable alternative. The lower production cost enhances economic viability of these ecosystems in Amazon as well as in the rest of the tropics. Such efficiency may have influenced the persistence of these managements, despite the worldwide agriculture intensification tendency.</p>
RESUMOEste estudo determinou o custo e o efeito de polímero hidrorretentor (hidrogel) na redução da mortandade de mudas de seis espécies florestais nativas do Cerrado, na recuperação de área degradada em Planaltina -Distrito Federal. Foram testados quatro tratamentos (com e sem hidrogel nas estações seca e chuvosa) em delineamento em blocos casualizados com quatro blocos e três repetições por bloco. ANOVA e teste de Tukey revelaram que o hidrogel reduziu significativamente a mortandade na estação seca, mas não teve efeito significativo na estação chuvosa. Considerando o custo de substituição de mudas mortas, o tratamento sem hidrogel foi mais caro que com hidrogel na estação seca. O plantio no final da estação seca com hidrogel representa alternativa viável para reduzir a mortandade de mudas via mitigação dos efeitos do estresse hídrico pós-transplante no final da estação seca, sem representar custo significativo adicional aos programas de recuperação de áreas degradadas de Cerrado.Palavras-chave: polímero hidrorretentor, recuperação de áreas degradadas, cerrado sensu stricto. Viability of Hydrogel in cerrado sensu stricto Revegetation with Native Species ABSTRACTWe determined the cost and effect of a water retention polymer (hydrogel) in reducing mortality of planted seedlings of six Cerrado forest species in the restoration of a degraded area in Planaltina county -Brazilian Federal District. We tested four treatments (hydrogel use and no hydrogel use in dry and rainy seasons) in a randomized block design, with four blocks and three replications per block. ANOVA and Tukey's test revealed that hydrogel significantly reduced mortality in the dry season, and had no significant effect in the rainy season. Regarding the cost of dead seedlings replacement, the treatment without hydrogel was more expensive than the one with hydrogel in the dry season. Planting at the end of the dry season using hydrogel is a viable alternative in reducing mortality of seedlings via mitigation of water stress effects after transplantation, without significant additional cost to recovery programs of Cerrado degraded areas.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.