Flathead High School

ABSTRACT Nutrient limitation of phytoplankton growth in a lake has various effects on lake function and primary producer composition. There is a rich history of using short‐term enrichment experiments to infer the type and degree of limitation in lakes. However, most experiments are analysed independently of one another, lack a common framework for expressing uncertainty, and only represent a single point in time. We conducted a series of phytoplankton nutrient limitation experiments in mountain lakes across northwestern Montana, USA to (a) assess regional patterns of nutrient limitation and (b) examine limitation through time in one large lake. We use a multilevel Bayesian model to better characterise parameter uncertainty across all experiments. The fertilisation effect of phosphorus was consistently larger than that of nitrogen, reflecting low phosphorus concentrations across lakes in this region. Most experiments showed evidence for P limitation or serial P limitation, with some evidence for independent co‐limitation as well. We also show that nutrient limitation in one lake changed over both a growing season and across years from strong P limitation to serial P limitation. Future work should continue to explore methods for analysing collections of nutrient limitation experiments.

While most global productivity is driven by modern photosynthesis, river ecosystems are supplied by locally fixed and imported carbon that spans a range of ages. Alluvial aquifers of gravel-bedded river floodplains present a conundrum: despite no possibility for photosynthesis in groundwater and extreme paucity of labile organic carbon, they support diverse and abundant large-bodied consumers (stoneflies, Insecta: Plecoptera). Here we show that up to a majority of the biomass carbon composition of these top consumers in four floodplain aquifers of Montana and Washington is methane-derived. The methane carbon ranges in age from modern to up to >50,000 years old and is mostly derived from biogenic sources, although a thermogenic contribution could not be excluded. We document one of the most expansive ecosystems to contain site-wide macroinvertebrate biomass comprised of methane-derived carbon and thereby advance contemporary understanding of basal resources supporting riverine productivity.

Summary Community-based stewardship forestry (CBSF) on public lands in the United States is still a fledgling concept. Neither the number of projects completed nor the length of time that has passed since their initial implementation has been sufficient to draw definitive conclusions about the movement's success in improving economic, social, and environmental conditions in forest-dependent communities. What is of most concern now is whether the CBSF fledgling will have a chance to reach its full potential or will instead fall victim to organizational exhaustion, economic malnutrition, or political sniping. Experiences with stewardship collaboratives in northwest Montana have helped define 10 key factors CBSF groups must effectively address if they are to survive: (1) organizational burnout; (2) membership composition, expansion, diversification, and utilization; (3) change in organizational mission or focus; (4) financial viability; (5) responsiveness of federal decision makers to CBSF groups' legislative concerns; (6) continued skepticism among both industry and environmental communities; (7) movement from small demonstration projects to implementation on a larger scale; (8) need for procedural simplification; (9) outreach to the broader community; and (10) institutionalization of a meaningful role for communities in the natural resource policy making and management process. There are no simple solutions to these challenges, but the collective record of CBSF groups so far suggests a level of commitment and staying power sufficient to propel the fledgling through the transition and into full flight.

During 1960s and early 1970s, Mysis relicta were introduced into more that 100 lakes throughout the northwestern U.S.