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The Polaris Project, a National Science Foundation-funded program at the Woodwell Climate Research Center, aims to comprehensively address minority participation in climate and Arctic science research. The project implemented design principles to recruit, motivate, and retain African Americans, Hispanics, Native Americans or Alaskan Natives, and women through immersive, field research experiences. The project included undergraduate and graduate students from environmental science, ecology, hydrology, biology, forestry, and geology. Ninety-five percent of participants identified as African American, Hispanic, Native American or Alaskan Native, and/or female. Critical participant outcomes included development of interdisciplinary research projects, involvement in self-efficacy and advocacy experiences, and increased awareness and discussion of Arctic research careers. All outcomes contributed to the Polaris Project's role as a model climate science research program.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2006.02.012 Byline: Susan M. Bertram, John D. Schade, James J. Elser Abstract: Recent findings in the field of ecological stoichiometry indicate that the relationships among key macronutrient elements (e.g. carbon, nitrogen and phosphorus) of organisms and their resources may underlie variation in fitness-conferring behaviours. The amount of phosphorus in an individual's body is often correlated with its rate of growth and reproduction, and low-phosphorus diets are known to reduce growth in a number of insect and crustacean herbivores. These findings suggest that the stoichiometric imbalance between organismal biomass requirements and the relative scarcity of nutrients in nature may underlie variation in condition-dependent behaviours. Here we investigate relationships between body elemental composition and long-distance mate attraction signals produced by male Texas field crickets, Gryllus texensis. Signalling was strongly and positively correlated with the percentage of phosphorus present in the body, but was not correlated with the percentage of carbon or nitrogen present. We also found evidence suggesting that callers and noncalling satellites differ in their elemental composition. To our knowledge, our data are the first to indicate that there may be a relationship between total body phosphorus content and a sexually selected trait. We present a preliminary evaluation of proximate hypotheses to account for the observed patterns. Our results indicate that a stoichiometric perspective may help us to understand the causes of variation in behaviour. Author Affiliation: School of Life Sciences, Arizona State University, U.S.A. Article History: Received 17 February 2005; Revised 28 May 2005; Accepted 27 February 2006 Article Note: (miscellaneous) MS. number: A10095R

Climate change is causing an intensification in tundra fires across the Arctic, including the unprecedented 2015 fires in the Yukon‐Kuskokwim (YK) Delta. The YK Delta contains extensive surface waters (∼33% cover) and significant quantities of organic carbon, much of which is stored in vulnerable permafrost. Inland aquatic ecosystems act as hot‐spots for landscape CO2 and CH4 emissions and likely represent a significant component of the Arctic carbon balance, yet aquatic fluxes of CO2 and CH4 are also some of the most uncertain. We measured dissolved CH4 and CO2 concentrations (n = 364), in surface waters from different types of waterbodies during summers from 2016 to 2019. We used Sentinel‐2 multispectral imagery to classify landcover types and area burned in contributing watersheds. We develop a model using machine learning to assess how waterbody properties (size, shape, and landscape properties), environmental conditions (O2, temperature), and surface water chemistry (dissolved organic carbon composition, nutrient concentrations) help predict in situ observations of CH4 and CO2 concentrations across deltaic waterbodies. CO2 concentrations were negatively related to waterbody size and positively related to waterbody edge effects. CH4 concentrations were primarily related to organic matter quantity and composition. Waterbodies in burned watersheds appeared to be less carbon limited and had longer soil water residence times than in unburned watersheds. Our results illustrate the importance of small lakes for regional carbon emissions and demonstrate the need for a mechanistic understanding of the drivers of greenhouse gasses in small waterbodies. Key Points: Waterbody size and shape have strong nonlinear effects on CO2, with the highest concentrations in small, complex, waterbodiesDissolved organic carbon quantity and composition are the most important drivers of CH4 concentrations in waterbodiesWildfires increase the sensitivity of waterbody CO2 and CH4 concentrations to degraded permafrost in upstream watersheds [ABSTRACT FROM AUTHOR]

1. Nutrient spiralling provides a conceptual framework and a whole-system approach to investigate ecosystem responses to environmental changes. We use spiralling metrics to examine how the coupling of nitrogen and phosphorus uptake varies between streams dominated by either heterotrophic (i.e. bacteria-dominated) or autotrophic (algal-dominated) microbial communities. 2. Algae generally exhibit greater capacity to store nutrients than bacteria because of differences in cellular structures. These differences led us to hypothesise that the uptake of N and P in heterotrophic ecosystems should have reduced stoichiometric variation in response to changes in supply N : P compared to autotrophic ecosystems when assimilation dominates nutrient uptake. 3. To test this hypothesis, we used an array of serial nutrient additions in several streams in the South Fork Eel River watershed in Northern California. In one set of experiments, N and P were added alone and simultaneously in separate experiments to two small, heterotrophic streams to assess uptake rates and interactions between nutrient cycles. In a second set of experiments, N and P were added simultaneously at a range of N : P in one heterotrophic and one autotrophic stream to assess differences in uptake responses to changes in supply N : P. 4. Results of these experiments suggest two important conclusions. First, increased N supply significantly shortened P uptake lengths, while P addition had little impact on N uptake in both streams, indicating that uptake of non-limiting nutrients is tightly coupled to the availability of the limiting element. Second, changes in P uptake and uptake ratios ( U : U) with increased supply N : P supported our hypothesis that heterotrophic streams are more homeostatic in their responses to changes in nutrient supply than autotrophic streams, suggesting that physiological controls on nutrient use scale up to influence ecosystem-scale patterns in nutrient cycling. [ABSTRACT FROM AUTHOR]

Human activities have resulted in increased nitrogen deposition and atmospheric CO2 concentrations in the biosphere, potentially causing significant changes in many ecological processes. In addition to these ongoing perturbations of the abiotic environment, human-induced losses of biodiversity are also of major concern and may interact in important ways with biogeochemical perturbations to affect ecosystem structure and function. We have evaluated the effects of these perturbations on plant biomass stoichiometric composition (C:N:P ratios) within the framework of the BioCON experimental setup (biodiversity, CO2, N) conducted at the Cedar Creek Natural History Area, Minnesota. Here we present data for five plant species: Solidago rigida, Achillea millefolium, Amorpha canescens, Lespedeza capitata, and Lupinus perennis. We found significantly higher C:N and C:P ratios under elevated CO2 treatments, but species responded idiosyncratically to the treatment. Nitrogen addition decreased C:N ratios, but this response was greater in the ambient CO2 treatments than under elevated CO2. Higher plant species diversity generally lowered both C:N and C:P ratios. Importantly, increased diversity also led to a more modest increase in the C:N ratio with elevated CO2 levels. In addition, legumes exhibited lower C:N and higher C:P and N:P ratios than non-legumes, highlighting the effect of physiological characteristics defining plant functional types. These data suggest that atmospheric CO2 levels, N availability, and plant species diversity interact to affect both aboveground and belowground processes by altering plant elemental composition. [ABSTRACT FROM AUTHOR]