Examinando por Autor "Ladd, B."
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Ítem Acceso Abierto Application of biochars to sandy and silty soil failed to increase maize yield under common agricultural practice(Elsevier, 2014) Borchard, N.; Siemens, J.; Ladd, B.; Möller, A.; Amelung, W.Adding biochar to tropical soils is a strategy for improving crop yield and mitigating climate change, but how various biochar types affect crop yield and the properties of temperate soils is still in dispute. Here, we evaluated how slow-pyrolysis charcoal and two biochars derived from energy production (gasification coke and flash-pyrolysis char) affected the growth of Zea mays L. and the related properties of sandy and silty soils within a 3-year mesocosm experiment. Fertilization was performed to optimize plant growth as would be done under common agricultural practice. Analyses included the monitoring of yield, plant and soil nutrients, aggregate stability, cation exchange and water holding capacity, and black carbon content. The results showed that the added biochars did not affect crop yield at an application rate of 15gbiocharkg-1 of soil. Increasing the application rate of slow-pyrolysis charcoal to 100gkg-1 resulted in decreased plant biomass in the second and third year of the experiment, likely as a result of nutrient imbalances and N-immobilization. We did not detect any degradation of the added black carbon; however, beneficial effects on plants were limited by the small and transient effect of these biochars on the physical and chemical properties of soil. Overall, our results indicate that the added carbon from biochars is stored in soil, but all treatments tested failed to improve plant yield for the studied temperate soils under the given application rates and common agricultural practice. © 2014 Elsevier B.V.Ítem Acceso Abierto Biochar research activities and their relation to development and environmental quality. A meta-analysis(Springer-Verlag France, 2017) Mehmood, K.; Chávez Garcia, E.; Schirrmann, M.; Ladd, B.; Kammann, C.; Wrage-Mönnig, N.; Siebe, C.; Estavillo, J.M.; Fuertes-Mendizabal, T.; Cayuela, M.; Sigua, G.; Spokas, K.; Cowie, A.L.; Novak, J.; Ippolito, J.A.; Borchard, N.Biochar is the solid product that results from pyrolysis of organic materials. Its addition to highly weathered soils changes physico-chemical soil properties, improves soil functions and enhances crop yields. Highly weathered soils are typical of humid tropics where agricultural productivity is low and needs to be raised to reduce human hunger and poverty. However, impact of biochar research on scientists, politicians and end-users in poor tropical countries remains unknown; assessing needs and interests on biochar is essential to develop reliable knowledge transfer/translation mechanisms. The aim of this publication is to present results of a meta-analysis conducted to (1) survey global biochar research published between 2010 and 2014 to assess its relation to human development and environmental quality, and (2) deduce, based on the results of this analysis, priorities required to assess and promote the role of biochar in the development of adapted and sustainable agronomic methods. Our main findings reveal for the very first time that: (1) biochar research associated with less developed countries focused on biochar production technologies (26.5 ± 0.7%), then on biochars’ impact on chemical soil properties (18.7 ± 1.2%), and on plant productivity (17.1 ± 2.6%); (2) China dominated biochar research activities among the medium developed countries focusing on biochar production technologies (26.8 ± 0.5%) and on use of biochar as sorbent for organic and inorganic compounds (29.1 ± 0.4%); and (3) the majority of biochar research (69.0±2.9%) was associated with highly developed countries that are able to address a higher diversity of questions. Evidently, less developed countries are eager to improve soil fertility and agricultural productivity, which requires transfer and/or translation of biochar knowledge acquired in highly developed countries. Yet, improving local research capacities and encouraging synergies across scientific disciplines and countries are crucial to foster development of sustainable agronomy in less developed countries. © 2017, The Author(s).Ítem Acceso Abierto Black carbon and soil properties at historical charcoal production sites in Germany(Elsevier, 2014) Borchard, N.; Ladd, B.; Eschemann, S.; Hegenberg, D.; Möseler, B.M.; Amelung, W.The use of charcoal as a soil amendment is currently of great interest to sequester carbon and improve soil fertility, however, studies of sites where charcoal amendments to the soil have been made many years ago are lacking at the moment. In this study we investigated historical charcoal production sites in Germany that have not been in use for >60years, and evaluated the effects of the former charcoal inputs on soil and vegetation parameters relative to those of adjacent, unamended areas. Surface soil samples (0-5, 5-20cm) were taken from five sites located on extremely acidic (Siegerland, pH3.8-4.1) and base rich soils (Eifel, pH4.8-5.3) in species poor (Luzulo-Fagetum) and species rich (Hordelymo-Fagetum) beech forests, respectively. We determined stocks of black carbon (BC) and natural soil organic carbon (SOC=total C minus BC) as well as of soil nutrient stocks (NO3-N, P, K, Mg), cation exchange capacity and water holding capacity, and we mapped plant composition to calculate richness and evenness. The results showed that historical charcoal production sites were enriched with BC and also exhibited increased stocks of natural SOC and total N possibly due to enhanced stabilization of natural SOC by the charcoal. The availability of nitrate-nitrogen, phosphate and potassium was increased when the charcoal was added to the base rich soils and less so when charcoal was added to the extremely acidic soils. Plant biodiversity was not different between the sites of historical charcoal addition and the reference sites. We conclude that charcoal additions may increase soil carbon storage capacity over prolonged periods of time without negatively affecting plant ecological interactions over the long term. © 2014 Elsevier B.V.Ítem Acceso Abierto Carbon accrual rates, vegetation and nutrient dynamics in a regularly burned coppice woodland in Germany(Blackwell Publishing Ltd, 2017) Borchard, N.; Adolphs, T.; Beulshausen, F.; Ladd, B.; Gießelmann, U.C.; Hegenberg, D.; Möseler, B.M.; Amelung, W.Historically, large areas of forest in Europe were managed as coppice woodland to produce wood-based fuel for the smelting industry. We hypothesized that this practice produced a legacy effect on current forest ecosystem properties. Specifically, we hypothesized that the historical form of coppicing may have produced a legacy of elevated stocks of soil organic carbon (SOC), nutrients and black carbon (BC) in soil as fire was routinely used in coppiced woodland to clear land. We further hypothesized that these changes in soil properties would result in increased biodiversity. To test these hypotheses, we sampled the surface soil (0–5, 5–10 and 10–20 cm) from a chronosequence of forest sites found in the Siegerland (Germany) that had been coppiced and burned 1, 2, 3.5, 6, 8, 11 and 17 years before present. Mature beech and spruce forests (i.e., >60 years) were also sampled as reference sites: to provide a hint of what might occur in the absence of human intervention. We measured stocks of SOC, BC, NO3-N, P, K, Mg, as well as cation exchange and water-holding capacity, and we mapped plant composition to calculate species richness and evenness. The results showed that coppicing in combination with burning soil and litter improved soil nutrient availability, enhanced biodiversity and increased SOC stocks. The SOC stocks and biodiversity were increased by a factor of three relative to those in the mature beech and spruce forests. This study shows that traditional coppicing practice may facilitate net C accrual rates of 20 t ha−1 yr−1 and maintain high biodiversity, indicating that aspects of traditional practice could be applied in current forest management to foster biodiversity and to mitigate climate change. © 2016 The Authors Global Change Biology Bioenergy Published by John Wiley & Sons Ltd.Ítem Acceso Abierto Carbon isotopic signatures of soil organic matter correlate with leaf area index across woody biomes(Blackwell Publishing Ltd, 2014) Ladd, B.; Peri, P.L.; Pepper, D.A.; Silva, L.C.R.; Sheil, D.; Bonser, S.P.; Laffan, S.W.; Amelung, W.; Ekblad, A.; Eliasson, P.; Bahamonde, H.; Duarte-Guardia, S.; Bird, M.1. Leaf area index (LAI), a measure of canopy density, is a key variable for modelling and understanding primary productivity, and also water use and energy exchange in forest ecosystems. However, LAI varies considerably with phenology and disturbance patterns, so alternative approaches to quantifying stand-level processes should be considered. The carbon isotope composition of soil organic matter (δ13CSOM) provides a time-integrated, productivity-weighted measure of physiological and stand-level processes, reflecting biomass deposition from seasonal to decadal time scales. 2. Our primary aim was to explore how well LAI correlates with δ13CSOM across biomes. 3. Using a global data set spanning large environmental gradients in tropical, temperate and boreal forest and woodland, we assess the strength of the correlation between LAI and δ13CSOM; we also assess climatic variables derived from the WorldClim database. 4. We found that LAI was strongly correlated with δ13CSOM, but was also correlated with Mean Temperature of the Wettest Quarter, Mean Precipitation of Warmest Quarter and Annual Solar Radiation across and within biomes. 5. Synthesis. Our results demonstrate that δ13CSOM values can provide spatially explicit estimates of leaf area index (LAI) and could therefore serve as a surrogate for productivity and water use. While δ13CSOM has traditionally been used to reconstruct the relative abundance of C3 versus C4 species, the results of this study demonstrate that within stable C3- or C4-dominated biomes, δ13CSOM can provide additional insights. The fact that LAI is strongly correlated to δ13CSOM may allow for a more nuanced interpretation of ecosystem properties of palaeoecosystems based on palaeosol 13C values. © 2014 The Authors.Ítem Acceso Abierto Carbon storage in a high-altitude Polylepis woodland in the Peruvian Andes(Birkhauser Verlag AG, 2014) Vásquez, E.; Ladd, B.; Borchard, N.Polylepis woodland occurs in Peru's tropical highlands at elevations between 3,500 and 5,000 m above sea level and Polylepis is the most common tree at timberline in South America. The objective of this study was to assess the total ecosystem carbon stock in a Polylepis incana woodland, i.e., aboveground biomass (canopy trees and understory), root biomass and soil carbon stocks were all quantified. As part of this study, an allometric equation for the quantification of the aboveground biomass of individual P. incana trees was developed for the first time. The most important carbon pool was the soil (39.7 ± 6.9 kg m-2) followed by the aboveground biomass of Polylepis trees (3.8 ± 0.7 kg m-2). The total ecosystem carbon stock was estimated to be 43.9 ± 7.6 kg m-2; thus, 90.6 % of the ecosystem carbon stock is soil carbon. © 2014 Swiss Botanical Society.Ítem Acceso Abierto Cookstoves: a design popular in Peru(Nature Publishing Group, 2014) Khatun, K.; Ladd, B.[No abstract available]Ítem Acceso Abierto How are soil carbon and tropical biodiversity related?(Cambridge University Press, 2016) Sheil, D.; Ladd, B.; Silva, L.C.R.; Laffan, S.W.; Van Heist, M.This article discusses how biological conservation can benefit from an understanding of soil carbon. Protecting natural areas not only safeguards the biota but also curtails atmospheric carbon emissions. Opportunities for funding biological conservation could potentially be greater if soil carbon content is considered. In this article current knowledge concerning the magnitude and vulnerability of soil carbon stocks is reviewed and the relationship of these stocks to biological conservation values is explored. Looking at two relatively well-studied tropical regions we find that 15 of 21 animal species of conservation concern in the Virunga Landscape (Central Africa), and nine of ten such species in the Federal District of Brazil (Central Brazil), rely on carbon-rich habitats (alluvial and/or wetlands). At national scales, densities of species, endemics and threatened taxa (plants, mammals, birds, reptiles, amphibians and fish) show positive and significant relations with mean soil carbon content in all but two cases (threatened amphibians and threatened fish). Of more than 1000 threatened species in 37 selected tropical nations, 85% rely on carbon-rich habitats. This tendency is observed in plants, mammals, reptiles, amphibians and crustaceans, while birds appear more evenly distributed. Research to clarify and explore these relationships is needed. Soil carbon offers major opportunities for conservation. © Foundation for Environmental Conservation 2016.Ítem Acceso Abierto Modelling soil carbon content in South Patagonia and evaluating changes according to climate, vegetation, desertification and grazing(MDPI AG, 2018) Peri, P.L.; Rosas, Y.M.; Ladd, B.; Toledo, S.; Lasagno, R.G.; Pastur, G.M.In Southern Patagonia, a long-term monitoring network has been established to assess bio-indicators as an early warning of environmental changes due to climate change and human activities. Soil organic carbon (SOC) content in rangelands provides a range of important ecosystem services and supports the capacity of the land to sustain plant and animal productivity. The objectives in this study were to model SOC (30 cm) stocks at a regional scale using climatic, topographic and vegetation variables, and to establish a baseline that can be used as an indicator of rangeland condition. For modelling, we used a stepwise multiple regression to identify variables that explain SOC variation at the landscape scale. With the SOC model, we obtained a SOC map for the entire Santa Cruz province, where the variables derived from the multiple linear regression models were integrated into a geographic information system (GIS). SOC stock to 30 cm ranged from 1.38 to 32.63 kg C m-2. The fitted model explained 76.4% of SOC variation using as independent variables isothermality, precipitation seasonality and vegetation cover expressed as a normalized difference vegetation index. The SOC map discriminated in three categories (low, medium, high) determined patterns among environmental and land use variables. For example, SOC decreased with desertification due to erosion processes. The understanding and mapping of SOC in Patagonia contributes as a bridge across main issues such as climate change, desertification and biodiversity conservation. © 2018 by the authors.Ítem Acceso Abierto Nitrogen pollution and the meltdown of urban ecosystems(Molecular Diversity Preservation International Publishing (MDPI), 2016) Ladd, B.Urban ecosystems are carrying an extinction debt. Mitigating this debt will require the development of a predictive framework that improves our understanding of the factors causing decline of native biodiversity in urban areas. I argue that nitrogen is a common currency around which such a predictive framework could be built. I first summarise the evidence that shows the probable extent of nitrogen enrichment in urban ecosystems. I then review the body of empirical evidence that describes how nitrogen enrichment affects ecosystem process and function. By unifying these two bodies of empirical evidence, I generate a series of testable hypotheses that may allow for a better understanding of native biodiversity loss in urban areas. © 2016 by the author.Ítem Acceso Abierto On the use of hedonic price indices to understand ecosystem service provision from urban green space in five Latin American megacities(MDPI AG, 2017) de Mola, U.L.; Ladd, B.; Duarte, S.; Borchard, N.; La Rosa, R.A.; Zutta, B.Latin American (LA) megacities are facing enormous challenges to provide welfare to millions of people who live in them. High rates of urbanization and limited administrative capacity of LA cities to plan and control urban growth have led to a critical deficit of urban green space, and therefore, to sub-optimal outcomes in terms of urban sustainability. This study seeks to assess the possibility of using real estate prices to provide an estimate of the monetary value of the ecosystem services provided by urban green space across five Latin American megacities: Bogota, Buenos Aires, Lima, Mexico City and Santiago de Chile. Using Google Earth images to quantify urban green space and multiple regression analysis, we evaluated the impact of urban green space, crime rates, business density and population density on real estate prices across the five mentioned megacities. In addition, for a subset of the data (Lima and Buenos Aires) we analyzed the effects of landscape ecology variables (green space patch size, connectivity, etc.) on real estate prices to provide a first insight into how the ecological attributes of urban green space can determine the level of ecosystem service provision in different urban contexts in Latin America. The results show a strong positive relationship between the presence of urban green space and real estate prices. Green space explains 52% of the variability in real estate prices across the five studied megacities. Population density, business density and crime had only minor impacts on real estate prices. Our analysis of the landscape ecology variables in Lima and Buenos Aires also show that the relationship between green space and price is context-specific, which indicates that further research is needed to better understand when and where ecological attributes of green space affect real estate prices so that managers of urban green space in LA cities can optimize ecological configuration to maximize ecosystem service provision from often limited green spaces. © 2017 by the authors.Ítem Acceso Abierto REDD+ en Latinoamérica: el caso de Perú [REDD+ in Latin America: the case of Peru](2013) Ladd, B.; Peri, P.L.The question of how developing countries like Peru can participate effectively in the REDD+ (reducing emissions from deforestation and forest degradation) policy initiative of the United Nations has been the focus of considerable debate recently. The aim of this study was to detect the main challenges associated with monitoring deforestation and forest degradation and also to analyze the policy challenges associated with implementing REDD in Peru. To participate effectively in this process, it is essential that the Peruvian national government formulates a national response since it is unlikely that provincial agencies managing natural resources will be able to develop the necessary expertise to carry out effective monitoring, reporting and verification, and because the underlying factors driving deforestation will require a large investment and a coordinated response at the country level.Ítem Acceso Abierto The effects of land management (grazing intensity) vs. the effects of topography, soil properties, vegetation type, and climate on soil carbon concentration in Southern Patagonia(Academic Press, 2016) Peri, P.L.; Ladd, B.; Lasagno, R.G.; Martínez Pastur, G.Grazing is an economically important activity in Southern Patagonia's steppe and woodland ecosystems. In the past, emphasis has been on maximizing the provisioning capacity of these ecosystems with little concern for the longer term conservation of the ecosystem services related to climate regulation, like carbon sequestration. This is changing rapidly as livestock producers in the region work to develop a certification scheme for sustainable land management for Patagonians rangelands. This study is a scientific contribution towards this broader social objective in which we test whether soil C concentration in topsoil (10 cm depth) can be used as an indicator of rangeland condition. Data on climate, soil chemistry, topography, ecosystem type and stocking rates were obtained from the PEBANPA network of permanent plots database for 145 sites across Southern Patagonia. These variables were used as independent variables in a partial least squares regression in which top soil C was the dependent variable. The effects of land use (stocking rate) on top soil C were barely detectable at the regional scale in Patagonia. Top soil C was however strongly associated with other independent variables, notably soil chemistry and climate variables and also vegetation type. Thus, changes in land use management may not have a significant impact on soil carbon sequestration in these types of ecosystems. This may be because many factors interact to determine top soil C such that the footprint of overgrazing on top soil C is drowned out at the regional scale by other variables. This highlights the need for further work to develop indicators for sustainable land management in the region. © 2016 Elsevier LtdÍtem Acceso Abierto Using knowledge of plant persistence traits to optimize strategies for post-mine ecological restoration on the peruvian altiplano(International Mountain Society, 2018) Flores-Alvarez, J.L.; Ladd, B.; Velez-Azañero, A.; De Mola, U.L.; Bonser, S.The Peruvian Altiplano is an important center of mining activity. As a key hotspot for endemic biodiversity in Peru, it also has conservation value. Thus, ecological restoration strategies need to be developed to ensure that mining impacts on these biodiversity values are minimized. As a step toward this larger objective, we measured the composition of the soil seed bank on the Peruvian Altiplano and compared it with the standing vegetation in different plant communities. We calculated evolved persistence traits to evaluate the suitability of topsoil removal, storage, and redeployment as an ecological restoration strategy for the Peruvian Altiplano. The comparison demonstrates low similarities (Sorensen Index for sites A: 0.15, B:0.27, C:0.11, and D:0.12) between the seed bank and the standing vegetation. The flora of the germinable soil seed bank is dominated by ephemeral species. Meanwhile, the standing flora contains a higher percentage of perennial species, many of which invest in the capacity to persist via resprouting from underground storage organs. It is clear that the well-established restoration technique of topsoil removal, storage, and redeployment needs to be tested and will probably need modification to be an effective strategy for the Peruvian Altiplano. The required modifications are relatively straightforward and would ensure that this low-cost and effective restoration technique could be applied to good effect on the Peruvian Altiplano. © 2018 Li Flores-Alvarez et al.