Nitrogen dynamics in red alder

Red alder (Alnus rubra Bong.) is recognized as an important source of nitrogen to ecosystems that it inhabits. I examined N dynamics within alder trees, alder leaf litter, and the soil beneath alder leaf litter. ¹⁵Nitrogen, a stable isotope of N, was used as a tracer to follow the movement of N through the various systems of interest. Red alder trees were labeled with ¹⁵NO₃⁻ and ¹⁵NH₄⁺ using the stem-injection method. Leaves were sampled 3 and 15 mo subsequent to injection within several crown positions, including top, bottom, proximal, medial, and distal. Stem injection of both ¹⁵NH₄⁺ and ¹⁵NO₃⁻ at levels approaching one percent of crown N effectively labeled red alder trees. Although more variable, ¹⁵NO₃⁻ may have been more efficient in initial labeling. The distribution of ¹⁵N was uniform at the time of the first sampling, but was diluted in the distal and top positions by the second sampling. There was a clear increase in total N concentration toward the periphery of the tree. This increase became more pronounced with increasing crown size and crown closure. Crown position with respect to light availability may be the most important determinant in crown N allocation in red alder foliage. To study the transfer of N from red alder trees to the soil, ¹⁵N-labeled red alder foliage was allowed to decompose in the field for 21 mo. The concentration of ¹⁵N was measured in remaining detritus and at 0-5 and 5-15 cm depths in four soil fractions below the detritus. The soil fractions investigated included the light- and heavy-fractions of the soil, the chloroform-labile (microbial biomass) pool, and the whole-soil. Some recovery of ¹⁵N was noted in vegetation growing in the plots. The alder litter lost 78% of its mass, 77% of the total initial N, and only 64% of the total initial ¹⁵N. Although the heavy-fraction contained 77 to 88% of the total nitrogen, the concentration of N in the light-fraction was 3.5 times that in the heavy-fraction. Whole-soil recoveries were higher than the summed fractions for total N and for ¹⁵N in the top 5 cm. Light-fractions exhibited higher percent recoveries of ¹⁵N than heavy-fractions. Percent recovery of ¹⁵N in the chloroform-labile N fraction was not significant. The majority of nitrogen released from the leaves was concentrated within the top five centimeters of soil. After 21 mo of decomposition, alder detritus acted as a net source of N, most of which remained in the labile pools of the fractionated soil

Fire effects on temperate forest soil C and N storage

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116995/1/eap20112141189.pd

Beyond planning tools: Experiential learning in climate adaptation planning and practices

In the past decade, several dedicated tools have been developed to help natural resources professionals integrate climate science into their planning and implementation; however, it is unclear how often these tools lead to on-the-ground climate adaptation. Here, we describe a training approach that we developed to help managers effectively plan to execute intentional, climate-informed actions. This training approach was developed through the Climate Change Response Framework (CCRF) and uses active and focused work time and peer-to-peer interaction to overcome observed barriers to using adaptation planning tools. We evaluate the effectiveness of this approach by examining participant evaluations and outlining the progress of natural resources projects that have participated in our trainings. We outline a case study that describes how this training approach can lead to place and context-based climate-informed action. Finally, we describe best practices based on our experience for engaging natural resources professionals and helping them increase their comfort with climate-informed planning

Ancient Plasmodium genomes shed light on the history of human malaria

Malaria-causing protozoa of the genus Plasmodium have exerted one of the strongest selective pressures on the human genome, and resistance alleles provide biomolecular footprints that outline the historical reach of these species1. Nevertheless, debate persists over when and how malaria parasites emerged as human pathogens and spread around the globe1,2. To address these questions, we generated high-coverage ancient mitochondrial and nuclear genome-wide data from P. falciparum, P. vivax and P. malariae from 16 countries spanning around 5,500 years of human history. We identified P. vivax and P. falciparum across geographically disparate regions of Eurasia from as early as the fourth and first millennia bce, respectively; for P. vivax, this evidence pre-dates textual references by several millennia3. Genomic analysis supports distinct disease histories for P. falciparum and P. vivax in the Americas: similarities between now-eliminated European and peri-contact South American strains indicate that European colonizers were the source of American P. vivax, whereas the trans-Atlantic slave trade probably introduced P. falciparum into the Americas. Our data underscore the role of cross-cultural contacts in the dissemination of malaria, laying the biomolecular foundation for future palaeo-epidemiological research into the impact of Plasmodium parasites on human history. Finally, our unexpected discovery of P. falciparum in the high-altitude Himalayas provides a rare case study in which individual mobility can be inferred from infection status, adding to our knowledge of cross-cultural connectivity in the region nearly three millennia ago.This project was funded by the National Science Foundation, grants BCS-2141896 and BCS-1528698; the European Research Council (ERC) under the European Union’s Horizon 2020 programme, grants 851511-MICROSCOPE (to S. Schiffels), 771234-PALEoRIDER (to W.H.) and starting grant 805268-CoDisEASe (to K.I.B.); and the ERC starting grant Waves ERC758967 (supporting K. Nägele and S.C.). We thank the Max Planck-Harvard Research Center for the Archaeoscience of the Ancient Mediterranean for supporting M. Michel, E. Skourtanioti, A.M., R.A.B., L.C.B., G.U.N., N.S., V.V.-M., M. McCormick, P.W.S., C.W. and J.K.; the Kone Foundation for supporting E.K.G. and A.S.; and the Faculty of Medicine and the Faculty of Biological and Environmental Sciences at the University of Helsinki for grants to E.K.G. A.S. thanks the Magnus Ehrnrooth Foundation, the Sigrid Jusélius Foundation, the Finnish Cultural Foundation, the Academy of Finland, the Life and Health Medical Foundation and the Finnish Society of Sciences and Letters. M.C.B. acknowledges funding from: research project PID2020-116196GB-I00 funded by MCIN/AEI/10.13039/501100011033; the Spanish Ministry of Culture; the Chiang Ching Kuo Foundation; Fundación Palarq; the EU FP7 Marie Curie Zukunftskolleg Incoming Fellowship Programme, University of Konstanz (grant 291784); STAR2-Santander Universidades and Ministry of Education, Culture and Sports; and CEI 2015 project Cantabria Campus Internacional. M.E. received support from the Czech Academy of Sciences award Praemium Academiae and project RVO 67985912 of the Institute of Archaeology of the Czech Academy of Sciences, Prague. This work has been funded within project PID2020-115956GB-I00 ‘Origen y conformación del Bronce Valenciano’, granted by the Ministry of Science and Innovation of the Government of Spain, and grants from the Canadian Institutes for Health Research (MZI187236), Research Nova Scotia (RNS 2023-2565) and The Center for Health Research in Developing Countries. D.K. is the Canada research chair in translational vaccinology and inflammation. R.L.K. acknowledges support from a 2019 University of Otago research grant (Human health and adaptation along Silk Roads, a bioarchaeological investigation of a medieval Uzbek cemetery). P.O. thanks the Jane and Aatos Erkko Foundation, the Finnish Cultural Foundation and the Academy of Finland. S. Peltola received support from the Emil Aaltonen Foundation and the Ella and Georg Ehrnrooth Foundation. D.C.S.-G. thanks the Generalitat Valenciana (CIDEGENT/2019/061). E.W.K. acknowledges support from the DEEPDEAD project, HERA-UP, CRP (15.055) and the Horizon 2020 programme (grant 649307). M. Spyrou thanks the Elite program for postdocs of the Baden-Württemberg Stiftung. Open access funding provided by Max Planck Society

Influences of nitrogen on carbon dynamics in forest soil and density fractions

Application of N fertilizer is a common forest management practice in the Pacific Northwest, yet the long-term influence of fertilization on forest soil properties is not well known. Although elevated N often increases mineralization of C and N from labile organic matter, negative effects have been documented in recalcitrant organic matter and whole soil. Using a series of paired plots in which one of each pair had undergone long-term N fertilization, I investigated the effects of elevated N on C and N mineralization in forest soils and organic fractions. The O2 horizons (O2), whole soils (WS), light fractions (LF), heavy fractions (HF), and physically recombined fractions (RF), from the paired plots were incubated in the laboratory for 300 d. For control soils, an additional "summed" fraction (SF), was computed from LF and HF results. Prior to analysis of the effects of elevated N, a general test of the density fractionation technique was conducted in the control soils. The LF and HF were hypothesized to represent labile and recalcitrant fractions in soil, but C and N were not substantially more stable in the HF during the incubation. Total cumulative respiration and N mineralization were similar for both the SF and the WS, but C and N mineralization in both fractions were higher than in the RF. The depressed respiration in the RF might be explained by an antagonistic interaction between the varied microbial communities that degrade LF and HF; in the heterogeneous WS, these communities may be spatially separated. The density separation technique appears to be a viable method for isolating and studying different soil fractions, but these fractions should be considered more carefully in the context of microbial interaction and soil spatial heterogeneity. Elevated N depressed cumulative respiration to a similar extent in all substrates. The mechanisms most involved in degrading these substrates are negatively affected by elevated N, but may not be the same in each substrate. While laboratory results may not withstand the variability of the natural environment, the potential for elevated N to stabilize C in soil suggests the need for more detailed field measurements

Incorporation of nitrogen from decomposing red alder leaves into plants and soil of a recent clearcut in Oregon

Nitrogen incorporation from red alder (Alnus rubra Bong.) into an Oregon upland mesic forest soil was studied by tracing the fate of 15N added as 15N-labeled alder leaf litter. The recovery of 15N in vegetation, litter, light- and heavy-fractions of the soil, the chloroform-labile (microbial biomass) pool, and the whole soil were investigated after a 21-month field incubation of the labeled litter. 15N abundances well in excess of normal values were measured in vegetation growing in the plots, perhaps 3% of the 15N excess initially added. Additionally, the recovery of initial 15N after 21 months was 31% in remaining litter, 34% in the upper 5 cm of soil, and 4% in the 5–15 cm depth class. Alder litter had lost 78% of its mass, 77% of the total initial N (14N + 15N), and 64% of the initial 15N. 15N recovery was higher in the light fraction than in the heavy fraction. The soil heavy fraction accounted for 77 to 88% of the total soil N; however, the concentration of N in the light fraction was 3.5 times that in the heavy fraction. Recovery of excess 15N in the chloroform-labile N fraction was not significantly different from zero. After 21 months of decomposition, alder detritus was a net source of N; most of which remained in the top 5 cm of soil where it was concentrated in the more labile pools of soil N, and some of which was incorporated into growing plant tissue.Keywords: nitrogen incorporation, nitrogen source, soil nitrogen, red alder (Alnus rubra), leaf litter, leaf decompositio

Black Carbon’s Properties and Role in the Environment: A Comprehensive Review

Produced from incomplete combustion of biomass and fossil fuel in the absence of oxygen, black carbon (BC) is the collective term for a range of carbonaceous substances encompassing partly charred plant residues to highly graphitized soot. Depending on its form, condition of origin and storage (from the atmosphere to the geosphere), and surrounding environmental conditions, BC can influence the environment at local, regional and global scales in different ways. In this paper, we review and synthesize recent findings and discussions on the nature of these different forms of BC and their impacts, particularly in relation to pollution and climate change. We start by describing the different types of BCs and their mechanisms of formation. To elucidate their pollutant sorption properties, we present some models involving polycyclic aromatic hydrocarbons and organic carbon. Subsequently, we discuss the stability of BC in the environment, summarizing the results of studies that showed a lack of chemical degradation of BC in soil and those that exposed BC to severe oxidative reactions to degrade it. After a brief overview of BC extraction and measurement methods and BC use for source attribution studies, we reflect upon its significance in the environment, first by going over a theory that it could represent parts of what is called the ‘missing sink’ of carbon in global carbon cycle models. Elaborating upon the relationship of BC with polycyclic hydrocarbons, we show its significance for the sorption and transport of pollutants. A description of pulmonary-respiratory health effects of soot BC inhalation is followed by a discussion on its impact on climate and climate change. We explain how soot BC acts as a global warming agent through light (and heat) absorption and how it reduces the snow’s albedo and promotes its uncharacteristic thawing. On a more positive note, we conclude this review by illustrating recent observations and simulations of how pyrolytic processes can stabilize plant carbon stocks in the form of biochar BC that can sequester carbon and can help mitigate climate change, in addition to improving soil fertility

Operationalizing environmental justice through tools and approaches of the Climate Change Response Framework

Presented at the Environmental justice in the Anthropocene symposium held on April 24-25, 2017 at the Lory Student Center, Colorado State University, Fort Collins Colorado. This symposium aims to bring together academics (faculty and graduate students), independent researchers, community and movement activists, and regulatory and policy practitioners from across disciplines, research areas, perspectives, and different countries. Our overarching goal is to build on several decades of EJ research and practice to address the seemingly intractable environmental and ecological problems of this unfolding era. How can we explore EJ amongst humans and between nature and humans, within and across generations, in an age when humans dominate the landscape? How can we better understand collective human dominance without obscuring continuing power differentials and inequities within and between human societies? What institutional and governance innovations can we adopt to address existing challenges and to promote just transitions and futures?Includes bibliographical references.The Forest Service recognizes that climate change poses a multi-generational challenge that spans borders, transcends unilateral solutions, and demands shared learning and resources (USDA Forest Service 2011). The Climate Change Response Framework (CCRF, www.forestadaptation.org) grew from this recognition, and was formally launched in 2009 to address the major challenges that land managers face when considering how to integrate climate change into their planning and management. Practitioners whose livelihoods and communities depend on healthy forests face daunting challenges when responding to rapid forest decline or preparing for future change, particularly tribal natural resources professionals and tribal communities (Vogesser et al. 2013). Emphasizing climate services support for these rural communities can help them build adaptive capacity in their cultural and economic systems, often considered fundamental to environmental justice. Supporting climate-informed decision-making by these practitioners and communities requires climate service organizations to show up, listen, and then creatively work with practitioners to meet their own goals on the lands they manage. The emphasis of the CCRF on stewardship goals, as opposed to climate change and its effects, represents a subtle but important shift in focus to people and their values

Black Carbon’s Properties and Role in the Environment: A Comprehensive Review

Produced from incomplete combustion of biomass and fossil fuel in the absence of oxygen, black carbon (BC) is the collective term for a range of carbonaceous substances encompassing partly charred plant residues to highly graphitized soot. Depending on its form, condition of origin and storage (from the atmosphere to the geosphere), and surrounding environmental conditions, BC can influence the environment at local, regional and global scales in different ways. In this paper, we review and synthesize recent findings and discussions on the nature of these different forms of BC and their impacts, particularly in relation to pollution and climate change. We start by describing the different types of BCs and their mechanisms of formation. To elucidate their pollutant sorption properties, we present some models involving polycyclic aromatic hydrocarbons and organic carbon. Subsequently, we discuss the stability of BC in the environment, summarizing the results of studies that showed a lack of chemical degradation of BC in soil and those that exposed BC to severe oxidative reactions to degrade it. After a brief overview of BC extraction and measurement methods and BC use for source attribution studies, we reflect upon its significance in the environment, first by going over a theory that it could represent parts of what is called the ‘missing sink’ of carbon in global carbon cycle models. Elaborating upon the relationship of BC with polycyclic hydrocarbons, we show its significance for the sorption and transport of pollutants. A description of pulmonary-respiratory health effects of soot BC inhalation is followed by a discussion on its impact on climate and climate change. We explain how soot BC acts as a global warming agent through light (and heat) absorption and how it reduces the snow’s albedo and promotes its uncharacteristic thawing. On a more positive note, we conclude this review by illustrating recent observations and simulations of how pyrolytic processes can stabilize plant carbon stocks in the form of biochar BC that can sequester carbon and can help mitigate climate change, in addition to improving soil fertility.soil carbon sequestration; carbon budget; atmospheric pollution; polycyclic aromatic hydrocarbons; climate; biochar