Mountains are among the most fragile environments on Earth
Full of biodiversity and resources, mountains provide services that both human and ecological communities depend on. However, mountains are under immense pressure from changing biogeochemical and climate conditions. Our goal is to 1) track changes in mountain resources like snow, nitrogen, and phosphorus over time, and to 2) understand how limited resources are connected across a variable landscape.
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Plants are the living foundation of ecosystems, and mountains are no exception. The diversity of tundra plants is truly amazing — lots of different species pack into very small spaces and completely different species inhabitat areas just a few meters away. We study changes in plant composition and diversity over time to better understand the threats that these diversity hotspots face, and how these changes will affect tundra system as a whole.
Where the rest of mountain life cannot persist, microbes find a way. We study microbes living in the highest glaciers and talus fields of Niwot Ridge, to better understand how microbes survive in extreme environments. We also study microbes as critical players in the cycling of nutrients and plant resource uptake, to better understand how this web of interactions buffers of accelerates physical change.
High-elevation lakes are focal points of the mountain landscape. There, we find food webs of phytoplankton and zooplankton that nimbly respond to ice off, flushes of cold snowmelt water, and warmer conditions at the height of the summer. We study long-term shifts in these aquatic communities as a window into the future of life on the mountain.
High-elevation ecosystems function like water towers. They store snow during the winter, and release snowmelt in the spring. Decades of water monitoring show how atmospheric deposition and permafrost thaw can affect the export of many constituents found in our water, such as nitrate, sulfate, and carbon.
Mountain ecosystems develop according to the physical processes of weathering, erosion, and sediment movement. We study the origin and evolution of topographic features at and surrounding Niwot Ridge, as well as how this geomorphology acts as a template on which biological processes develop and change.
At the highest points on the tundra, we collect data on the Earth's atmosphere, climate, and interactions with the Earth’s surface. We measure atmospheric deposition and pollution, use flux towers to understand land-air exchange of carbon and energy, and track changes in temperature and precipitation — many of these records making history as the longest running measures in the continental US.
Mountain animals live at the edge of environmental extremes, and climate change is making their persistence even more uncertain. Studies of animals like pika, marmots, and bees provide indicators of environmental change through shifts in their abundance and distribution over time.
Photo of black sand application at one of the five manipulative the plots. (Chiara Forrester)
Photo taken A few days after initial black sand application (Chiara Forrester).
In 2018, we initiated a multi-year manipulative experiment to better understand the impacts of earlier snowmelt on tundra ecosystems. At peak snow-pack each year, we apply a thin layer of inert black vitreous sand over the snow in each of 5 manipulative plots. Black sand is also added to paired control plots after snowmelt. Within this experiment, we are measuring a variety of ecological responses with methods that allow for comparisons with our long-term monitoring (e.g. plant composition and biomass, soil temperature and soil moisture).
In 2019, we began testing how reduced flushing rates (associated with earlier ice-off on lakes) and increased dissolved organic material (DOM) (associated with encroachment of terrestrial plants in the alpine watershed) interactively affect planktonic biomass and community structure. We will include four replicates per treatment (20 tanks total) for 48 total mesocosms. Although mesocosms cannot capture the full complexity of biological and abiotic interactions unfolding within lakes, we use them here as one of several lines of investigation (alongside long-term data, comparative sampling over an elevation gradient, and ecosystem modeling) to specifically address interactions between phytoplankton and zooplankton.
Visualization of hypothesized effects of increased dissolved organic material and warming on aquatic communities. (Created by Kelly Loria)
We recently installed a wireless sensor network across the Saddle catchment that provides real-time field measurements of air temperature and humidity, snow depth, soil moisture and temperature, and plant productivity and phenology (phenocams). The instrumented area extends from the Saddle site into the Green Lakes Valley through subalpine forest to the saddle stream water sampling site (north of Lake Albion). These detailed measurements will help us better understand spatial variation in patterns of water- vs energy- limitation in our system, as well as provide baseline data for improved modeling of hydrology and connectivity across the landscape.
