2009 LTER All Scientists Meeting - NWT

Niwot Ridge LTER Program: Alpine Ecosystems as Early Warning Systems

Mark Williams — Tue, 01 Sep 2009 17:42:43 +0000

Poster Number:

377

Presenter/Primary Author:

Mark Williams

Co-Authors:

Tim Seastedt

Co-Authors:

Diane McKnight

Co-Authors:

Alan Townsend

Co-Authors:

Bill Bowman

Co-Authors:

Steve Schmidt

Co-Authors:

Peter Blanken

The Niwot Ridge (NWT) LTER site was one of the five original LTER sites established in 1980. The LTER program is based at the University of Colorado-Boulder and is administered through the Institute of Arctic and Alpine Research (INSTAAR) and in cooperation with the Mountain Research Station, with special use permits from the US Forest Service.

Spatio-temporal variability in alpine plant species composition on Niwot Ridge, Colorado

Hope Humphries — Tue, 01 Sep 2009 01:34:12 +0000

Poster Number:

364

Presenter/Primary Author:

Hope Humphries

Co-Authors:

Christophe F. Randin

Co-Authors:

Nigel G. Yoccoz

Co-Authors:

Katherine N. Suding

Spatial and temporal changes in alpine plant species composition were analyzed at the landscape, plant community, and individual species levels. We standardized field observations for 88 gridded vegetation plots sampled in 1990, 1997, and 2006 on Niwot Ridge, Colorado and developed spatial environmental data for the study area (snow cover, growing-degree days, time of meltout, and solar radiation). At the landscape scale, growing-degree days increased from 1990 to 2006, while the snow-covered period decreased and meltout occurred earlier.

Effects of forest die-back on soil biological and chemical characteristics of a Colorado Lodgepole pine forest

Tim Seastedt — Mon, 31 Aug 2009 21:03:50 +0000

Poster Number:

353

Presenter/Primary Author:

Yanmei Xiong

Co-Authors:

Tim Seastedt

A forest die-back caused by a beetle outbreak on lodgepole and limber pine was used to assess the relative importance of root inputs to the soil food web and chemistry of soils in the Colorado Front Range. We measured a suite of biological and chemical parameters at six sites containing both live and dead trees. We found an increase in amounts of soil inorganic N, decreased soil lable C, and thus a decreased soil labile C:N ratio.

Student Poster:

Yes

Linking Carbon Quality to In-stream Nitrogen Processing, Boulder Creek, Colorado

Rebecca Barnes — Mon, 31 Aug 2009 18:49:27 +0000

Poster Number:

335

Presenter/Primary Author:

Rebecca Barnes

Co-Authors:

Richard L. Smith

Dissolved organic matter (DOM) dominates the material and energy fluxes within aquatic ecosystems. Carbon fuels the majority of microbial processes, including those that regulate in-stream nitrogen constituents. DOM sources and in situ transformations determine its chemical nature and lability within aquatic systems. Boulder Creek, which is located in the Colorado Front Range and spans an ecosystem gradient from the Continental Divide to the high plains, receives excess atmospheric nitrogen deposition due to its proximity to population centers and agricultural lands.

Carbon cycling above treeline: eddy covariance results from high-elevation alpine tundra at Niwot Ridge, Colorado.

John Knowles — Mon, 31 Aug 2009 18:44:49 +0000

Poster Number:

333

Presenter/Primary Author:

John Knowles

Co-Authors:

Peter D. Blanken

Co-Authors:

Mark W. Williams

Ecosystems in topographically complex (mountainous) terrain are responsible for a majority of land-atmosphere CO2 exchange (net ecosystem exchange; NEE) across the western United States due to high inputs of winter precipitation as snowfall. NEE in these regions has been historically difficult to quantify using the eddy covariance (EC) method, however, due to complexities in surface terrain that lead to irregularities in streamline air flow, particularly advective fluxes during periods of low turbulent mixing.

Student Poster:

Yes

Climate change and soil temperature response across a montane to alpine gradient, Niwot Ridge LTER

Kurt Chowanski — Thu, 27 Aug 2009 16:12:38 +0000

Poster Number:

282

Presenter/Primary Author:

Kurt Chowanski

Co-Authors:

Timothy Kittel

Co-Authors:

Isabel W Ashton

Co-Authors:

Mark Williams

Soil temperature is one of the key determinants of carbon flux, nutrient availability, decomposition rates, and primary productivity in high-elevation and high-latitude ecosystems. Global climate models predict that as air temperatures rise there will be a corresponding increase in soil temperature and a longer snow-free season.

Biogeography of Bacterial Diversity and Function Across a Heterogeneous Alpine Landscape

Andrew King — Tue, 04 Aug 2009 19:53:15 +0000

Poster Number:

198

Presenter/Primary Author:

Andrew King

Co-Authors:

Kristen R. Freemen

Co-Authors:

Katherine F. McCormick

Co-Authors:

Micah Hamady

Co-Authors:

Catherine Lozupone

Co-Authors:

Rob Knight

Co-Authors:

Steve K. Schmidt

Microorganisms have confounded biogeographers because of their high dispersal capability, small size, and vast diversity and abundance. Here we use pyrosequencing, bioinformatics tools, and geospatial modeling to reveal that the genetic relatedness of soil bacteria varies in a predictable pattern across a landscape. Microbial communities showed strong spatial autocorrelation to a distance of 240 meters and this pattern was driven by changes in the genetic relatedness and abundance of specific clades across the landscape.

Student Poster:

Yes

Three-dimensional quantification of meltwater flow through a snowpack using a snow guillotine

Jennifer Petrzelka — Thu, 23 Jul 2009 21:35:46 +0000

Poster Number:

181

Presenter/Primary Author:

Jennifer Petrzelka

Co-Authors:

Erickson, Tyler A

Co-Authors:

Williams, Mark W

In areas containing seasonal snowpacks, snowmelt contributes significantly to the hydrological cycle. Thus, quantifying the spatial distribution of flow through a snowpack is essential to accurate hydrograph interpretation and representation in snowmelt runoff modeling. Movement of liquid water through snowpacks is generally recognized to occur in distinct flow paths rather than as uniform flow through a homogeneous porous medium.

Student Poster:

Yes

An automated system for continuous measurements of trace gas fluxes through snow: an evaluation of the gas diffusion method at a subalpine forest site, Niwot Ridge, Colorado

Brian Seok — Tue, 21 Jul 2009 23:23:08 +0000

Poster Number:

175

Presenter/Primary Author:

Brian Seok

Co-Authors:

Detlev Helmig

Co-Authors:

Mark W Williams

Co-Authors:

Daniel Liptzin

Co-Authors:

Kurt Chowanski

Co-Authors:

Jacques Hueber

An experimental system for sampling trace gas fluxes through seasonal snowpack was deployed at a subalpine site near treeline at Niwot Ridge, Colorado. The sampling manifold was in place throughout the entire snow-covered season for continuous air sampling with minimal disturbance to the snowpack. A series of gases (carbon dioxide, water vapor, nitrous oxide, nitric oxide, ozone, volatile organic compounds) was determined in interstitial air withdrawn at eight heights in and above the snowpack at ~hourly intervals.

Student Poster:

Yes

Use of isotopic and geochemical tracers to identify source waters, flow paths, and residence times of headwater catchments in Boulder Creek Watershed, Colorado

Rory Cowie — Tue, 21 Jul 2009 17:41:25 +0000

Poster Number:

172

Presenter/Primary Author:

Rory Cowie

Co-Authors:

Mark Williams

Co-Authors:

Peter Atkins

An outstanding question for snowmelt-dominated watersheds of the western US is the response of stream flow to changes in climate. We know little about mountain aquifers because they commonly involve structurally complicated rocks, extreme head gradients (ground slope angles 10-40°), and dramatically fluctuating recharge due to seasonal snow-melt. In general, the western United States is predicted to face warmer temperatures and more frequent and prolonged droughts, and we can expect to see a decrease in annual snowpack, earlier onset of snowmelt, and increased evaporation.

Student Poster:

Yes