Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Purpose</jats:title> <jats:p>Degraded ecosystems can be maintained by abiotic and biotic legacies long after initial disturbances, preventing recovery. These legacies can include changes in arbuscular mycorrhizal fungi (AMF). To inform potential restoration pathways, we aimed to elucidate differences in AMF between intact and degraded ecosystems, their responses to modified soils, and interactions with invasive plants.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>We used a state-and-transition framework to characterise AMF communities, native and exotic plant cover, and soil physicochemical properties across little-modified reference states and degraded states, which were carbon (C) and nitrogen (N) -depleted, intermediate, and CN-enriched, in temperate eucalypt woodlands of south-eastern Australia.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Most ground-layer states differed significantly in their AMF communities, with the CN-enriched states being most distinct. All states had unique taxa and characteristic indicator taxa, but intermediate and CN-enriched states harboured four-to-five times more indicator taxa than the reference state. Consistent with this, richness of AMF was higher in the intermediate and CN-enriched states than in reference states, driven by higher richness of Archaeosporaceae, Diversisporaceae, Glomeraceae, and Paraglomeraceae. Pathway analysis indicated that differences in AMF communities among states were strongly related to differences in native:exotic plant cover ratio, mediated by soil organic matter and nutrients.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>Our results indicate that ecosystem degradation is associated with both loss of AMF taxa and introduction of ‘weedy’ AMF, which in turn potentially contribute to maintenance of degraded ecosystems. We argue that our state-and-transition approach to characterising AMF communities improved our understanding of the different pathways of degradation, elucidating possible constraints to ecosystem recovery.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background and aims</jats:title> <jats:p>Forecasted climate change and overgrazing are threatening the sustainability of dehesas, human-managed ecosystems where pastures, livestock and scattered trees coexist. Pasture quality is particularly sensitive to these global-change drivers, but there are still many gaps to broaden knowledge about the interactive effects of both factors on it. In addition, scattered trees might play a relevant role in maintaining high levels of pasture quality under future scenarios of higher aridity, but its role remains largely unexplored.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>We designed a field manipulative experiment of rainfall exclusion and increased temperature aimed to evaluate the impact of forecasted climate on pasture quality under different historical grazing intensities. To test the potential buffering effect of trees, experimental plots were installed equally in two habitat types: under trees and open grassland.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Warming reduced the nutrient concentration of pasture, while drought increased it. Tree canopy improved soil fertility, which translated into an increase in pasture quality. Livestock exclusion and high grazing intensity caused a decrease in pasture quality, whereas moderate grazing intensity exerted positive effects on it. Finally, warming beneath tree canopy negatively affected the P concentration of pasture, specifically in the site subjected to moderate grazing intensity.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>Our findings suggest that communities subjected to moderate grazing are more sensitive to climate change from a nutritional standpoint, likely because this management type provides high levels of P to the soil. In addition, we highlight the essential role of trees in agroforestry ecosystems to maintain high values of nutritional quality of pasture.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>Increasing zinc (Zn) concentrations in maize grains could contribute to alleviating widespread human Zn deficiency in sub-Saharan Africa (SSA). However, trade-offs between grain Zn concentrations and maize yields have been observed.</jats:p> </jats:sec><jats:sec> <jats:title>Scope</jats:title> <jats:p>Using data from researcher-managed, on-farm and on-station field trials in Kenya, Zambia and Zimbabwe, we aimed (i) to confirm whether this trade-off is found in current farming systems in SSA and (ii) to explore whether genotypic and management options, relevant for the African context, can increase both yields and grain Zn concentrations across several environments.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>An overall negative, but weak relation between maize yields and grain Zn concentrations was found. High yields and high grain Zn concentrations did not co-occur. The negative relation between grain Zn concentrations and yields cannot be bypassed by selecting one of the commercially available varieties used in this study. Nitrogen application increased yields, but had contrasting effects on grain Zn concentrations depending on variety and site. Grain Zn concentrations were positively related with soil organic carbon and P and K availability.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Attaining grain Zn concentrations above the HarvestPlus target of 38 mg kg<jats:sup>−1</jats:sup>, considered adequate for reducing human Zn deficiency, with current commercially available maize varieties and presented management options, is not possible without compromising yield levels. Increasing soil organic matter content and balanced application of N, P and K fertilisers could increase grain Zn concentrations. These practices likely will also increase yields and could be a viable option to bypass the trade-off between maize yields and grain Zn concentrations.</jats:p> </jats:sec>

<jats:title>Abstract </jats:title><jats:sec> <jats:title>Aims</jats:title> <jats:p>This study aimed at elucidating divergent effects of two dominant plant functional types (PFTs) in tundra heath, dwarf shrubs and mosses, on soil microbial processes and soil carbon (C) and nutrient availability, and thereby to enhance our understanding of the complex interactions between PFTs, soil microbes and soil functioning.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>Samples of organic soil were collected under three dwarf shrub species (of distinct mycorrhizal association and life form) and three moss species in early and late growing season. We analysed soil C and nutrient pools, extracellular enzyme activities and phospholipid fatty acid profiles, together with a range of plant traits, soil and abiotic site characteristics.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Shrub soils were characterised by high microbial biomass C and phosphorus and phosphatase activity, which was linked with a fungal-dominated microbial community, while moss soils were characterised by high soil nitrogen availability, peptidase and peroxidase activity associated with a bacterial-dominated microbial community. The variation in soil microbial community structure was explained by mycorrhizal association, root morphology, litter and soil organic matter quality and soil pH-value. Furthermore, we found that the seasonal variation in microbial biomass and enzyme activities over the growing season, likely driven by plant belowground C allocation, was most pronounced under the tallest shrub <jats:italic>Betula nana</jats:italic>.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>Our study demonstrates a close coupling of PFTs with soil microbial communities, microbial decomposition processes and soil nutrient availability in tundra heath, which suggests potential strong impacts of global change-induced shifts in plant community composition on carbon and nutrient cycling in high-latitude ecosystems.</jats:p> </jats:sec>