Dr. James Petersen was killed during an armed robbery while doing research near Manaus, Brazil, on 13 Aug. 2005. Dr. Petersen was associate professor and chair of the Anthropology Department at University of Vermont. We will miss him as a valued colleague and good friend.

This study investigates the spatial distribution of organic carbon (C) in free stable microaggregates (20-250 m; not encapsulated within macroaggregates) from one Inceptisol and two Oxisols in relation to current theories of the mechanisms of their formation. Two-dimensional micro-and nano-scale observations using synchrotron-based Fourier-transform infrared (FTIR) and near-edge X-ray absorption Wne structure (NEXAFS) spectroscopy yielded maps of the distribution of C amounts and chemical forms. Carbon deposits were unevenly distributed within microaggregates and did not show any discernable gradients between interior and exterior of aggregates. Rather, C deposits appeared to be patchy within the microaggregates. In contrast to the random location of C, there were micronscale patterns in the spatial distribution of aliphatic C-H (2922 cm ). Aliphatic C forms and the ratio of aliphatic C/ aromatic C were positively correlated (r 2 of 0.66-0.75 and 0.27-0.59, respectively) to the amount of O-H on kaolinite surfaces (3695 cm ¡1 ), pointing at a strong role for organomineral interactions in C stabilization within microaggregates and at a possible role for molecules containing aliphatic C-H groups in such interactions. This empirical relationship was supported by nanometer-scale observations using NEXAFS which showed that the organic matter in coatings on mineral surfaces had more aliphatic and carboxylic C with spectral characteristics resembling microbial metabolites than the organic matter of the entire microaggregate. Our observations thus support models of C stabilization in which the initially dominant process is adsorption of organics on mineral surfaces rather than occlusion of organic debris by adhering clay particles.

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[1] Small-scale heterogeneity of organic carbon (C) forms in soils is poorly quantified since appropriate analytical techniques were not available up to now. Specifically, tools for the identification of functional groups on the surface of micrometer-sized black C particles were not available up to now. Scanning Transmission X-ray Microscopy (STXM) using synchrotron radiation was used in conjunction with Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy to investigate nano-scale distribution (50-nm resolution) of C forms in black C particles and compared to synchrotron-based FTIR spectroscopy. A new embedding technique was developed that did not build on a C-based embedding medium and did not pose the risk of heat damage to the sample. Elemental sulfur (S) was melted to 220°C until it polymerized and quenched with liquid N 2 to obtain a very viscous plastic S in which the black C could be embedded until it hardened to a noncrystalline state and was ultrasectioned. Principal component and cluster analysis followed by singular value decomposition was able to resolve distinct areas in a black carbon particle. The core of the studied biomass-derived black C particles was highly aromatic even after thousands of years of exposure in soil and resembled the spectral characteristics of fresh charcoal. Surrounding this core and on the surface of the black C particle, however, much larger proportions of carboxylic and phenolic C forms were identified that were spatially and structurally distinct from the core of the particle. Cluster analysis provided evidence for both oxidation of the black C particle itself as well as adsorption of non-black C. NEXAFS spectroscopy has great potential to allow new insight into black C properties with important implications for biogeochemical cycles such as mineralization of black C in soils and sediments, and adsorption of C, nutrients, and pollutants as well as transport in the geosphere, hydrosphere, and atmosphere.

In Uganda, Ghana and Bangladesh, participatory tools were used for a socio-economic and gender analysis of three topics: climate-smart agriculture (CSA), climate analogue approaches, and climate and weather forecasting. Policy and programmerelevant results were obtained. Smallholders are changing agricultural practices due to observations of climatic and environmental change. Women appear to be less adaptive because of financial or resource constraints, because of male domination in receiving information and extension services and because available adaptation strategies tend to create higher labour loads for women. The climate analogue approach (identifying places resembling your future climate so as to identify potential adaptations) is a promising tool for increasing farmer-to-farmer learning, where a high degree of climatic variability means that analogue villages that have successfully adopted new CSA practices exist nearby. Institutional issues related to forecast production limit their credibility and salience, particularly in terms of women's ability to access and understand them. The participatory tools used in this study provided some insights into women's adaptive capacity in the villages studied, but not to the depth necessary to address women's specific vulnerabilities in CSA programmes. Further research is necessary to move the discourse related to gender and climate change beyond the conceptualization of women as a homogenously vulnerable group in CSA programmes.

We present a framework for prioritizing adaptation approaches at a range of timeframes. The framework is illustrated by four case studies from developing countries, each with associated characterization of uncertainty. Two cases on near-term adaptation planning in Sri Lanka and on stakeholder scenario exercises in East Africa show how the relative utility of capacity vs. impact approaches to adaptation planning differ with level of uncertainty and associated lead time. An additional two cases demonstrate that it is possible to identify uncertainties that are relevant to decision making in specific timeframes and circumstances. The case on coffee in Latin America identifies altitudinal thresholds at which incremental vs. transformative adaptation pathways are robust options. The final case uses three crop-climate simulation studies to demonstrate how uncertainty can be characterized at different time horizons to discriminate where robust adaptation options are possible. We find that impact approaches, which use predictive models, are increasingly useful over longer lead times and at higher levels of greenhouse gas emissions. We also find that extreme events are important in determining predictability across a broad range of timescales. The results demonstrate the potential for robust knowledge and actions in the face of uncertainty.climate change | food security | vulnerability | future scenarios | policy A chieving food security under climate change is a complex public policy issue, a so-called "wicked problem." The magnitude of plausible impacts, and costs of inaction or delayed action, mean that individuals and societies must undertake adaptation actions despite uncertainty. Policymakers are accustomed to making decisions under considerable uncertainty and do not necessarily need systematic reductions in uncertainty to act on climate change (1). Nonetheless, science can make a major contribution by elucidating or prioritizing uncertainties in ways that are helpful to the decision-making processes of national policymakers and other stakeholders (2-4). The purpose of this article is to demonstrate how science can provide practical approaches to addressing uncertainty that can assist adaptation planning for agriculture in developing countries over multiple lead times. We achieve this goal by presenting four case studies linked by a framework that combines a simple uncertainty analysis with a characterization of different approaches to adaptation planning. Impact and Capacity Approaches to Adaptation PlanningAdaptation planning can incorporate scientific information both from projections of climatic impacts and assessments of adaptive capacity (Fig. 1). Impact approaches (5, 6) use statistical or mechanistic models to attach probabilities to possible outcomes under a range of scenarios; they arrive at adaptation options for agriculture and food security via analyses that start with climate forcings and global circulation models, and from these project progressive impacts on local climates, crop physiology, crop yi...

Natural organic matter (NOM) is a highly active component of soils and sediments, and plays an important role in global C cycling. However, NOM has defied molecular‐level structural characterization, owing to variations along the decomposition continuum and its existence as highly functionalized polyelectrolytes. We conducted a comprehensive systematic overview of spectral signatures and peak positions of major organic molecules that occur as part of NOM using near‐edge x‐ray absorption fine structure (NEXAFS) spectroscopy. The spectra of carbohydrates and amino sugars show resonances between 289.10 and 289.59 eV, attributed to 1s‐3p/σ* transitions of O‐alkyl (C‐OH) moieties. They also exhibited distinct peaks between 288.42 and 288.74 eV, representing C 1s–π*C = O transition from COOH functionalities. Amino acids produced a strong signal around 288.70 eV, which can be identified as a C 1s–π*C=O transition of carboxyl/carbonyl (COOH/COO‐) structures. Spectral features near 285.29 eV were ascribed to C 1s–π*C=C transition of ring structure of aromatic amino acids, while spectra between 287.14 and 287.86 eV were attributed to C 1s–π*C‐H and C 1s–σ*C‐H/3p Rydberg‐like excitations from CH and CH2 groups. Phenols and benzoquinone produced strong resonances between 285.08 and 285.37 eV, attributed to the π* orbital of C (C 1s–π*C=C) atoms connected to either C or H (C–H) in the aromatic ring. The next higher excitation common to both phenols and quinone appeared between 286.05 and 286.35 eV, and could be associated with C 1s–π*C=C transitions of aromatic C bonded to O atom in phenols, and to C 1s–π*C=O transitions from aromatic C connected to O atom (C‐OH) in phenols or to a C=O in p‐benzoquinone and some phenols with carbonyl structures, respectively. Nucleobases exhibited complex spectral features with pronounced resonances between 286.02 and 286.84 eV and between 288.01 and 288.70 eV. Molecular markers for black C (benzenecarboxylic acid and biphenyl‐4,4′‐dicarboxylic acid) exhibit sharp absorption bands between 285.01 and at 285.43 eV, possibly from C 1s–π*C=C transition characteristic of C‐H sites or unsaturated C (C=C) on aromatic ring structures. These aromatic carboxylic acids also exhibit broad peaks between 288.35 and 288.48 eV, reflecting C 1s–π*C=O transition of carboxyl functional groups bonded to unsaturated C. This investigation provides a more comprehensive NEXAFS spectral library of biogeochemically relevant organic C compounds. The spectra of these reference organic compounds reveal distinct spectral features and peak positions at the C K‐edge that are characteristic of the molecular orbitals bonding C atoms. Detailed structural information can be derived from these distinctive spectral features that could be used to build robust peak assignment criteria to exploit the chemical sensitivity of NEXAFS spectroscopy for in situ molecular‐level spatial investigation and fingerprinting of complex organic C compounds in environmental samples.

In the highlands of Western Kenya, we investigated the reversibility of soil productivity decline with increasing length of continuous maize cultivation over 100 years (corresponding to decreasing soil organic carbon (SOC) and nutrient contents) using organic matter additions of differing quality and stability as a function of soil texture and inorganic nitrogen (N) additions. The ability of additions of labile organic matter (green and animal manure) to improve productivity primarily by enhanced nutrient availability was contrasted with the ability of stable organic matter (biochar and sawdust) to improve productivity by enhancing SOC. Maize productivity declined by 66% during the first 35 years of continuous cropping after forest clearing. Productivity remained at a low level of 3.0 t grain ha -1 across the chronosequence stretching up to 105 years of continuous cultivation despite full N-phosphorus (P)-potassium (K) fertilization (120-100-100 kg ha )1 ). Application of organic resources reversed the productivity decline by increasing yields by 57-167%, whereby responses to nutrient-rich green manure were 110% greater than those from nutrient-poor sawdust. Productivity at the most degraded sites (80-105 years since forest clearing) increased in response to green manure to a greater extent than the yields at the least degraded sites (5 years since forest clearing), both with full N-P-K fertilization. Biochar additions at the most degraded sites doubled maize yield (equaling responses to green manure additions in some instances) that were not fully explained by nutrient availability, suggesting improvement of factors other than plant nutrition. There was no detectable influence of texture (soils with either 11-14 or 45-49% clay) when low quality organic matter was applied (sawdust, biochar), whereas productivity was 8, 15, and 39% greater (P < 0.05) on sandier than heavier textured soils with high quality organic matter (green and animal manure) or only inorganic nutrient additions, respectively. Across the entire degradation range, organic matter additions decreased the need for additional inorganic fertilizer N irrespective of the quality of the organic matter. For low quality organic resources (biochar and sawdust), crop yields were increasingly responsive to inorganic N fertilization with increasing soil degradation. On the other hand, fertilizer N additions did not 726improve soil productivity when high quality organic inputs were applied. Even with the tested full N-P-K fertilization, adding organic matter to soil was required for restoring soil productivity and most effective in the most degraded sites through both nutrient delivery (with green manure) and improvement of SOC (with biochar).