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Community Land Model version 4.5 (CLM4.5) simulations of water, energy, and carbon fluxes for Saddle vegetation communities, 2008 - 2013

Single point simulations of CLM4.5 that include (1) forcing data that were input to the model and subsequent (2) model output for simulations that approximate conditions in fellfield, dry meadow, moist meadow, wet meadow, and snowbed vegetation communities. Forcing data were generated with observed atmospheric conditions from Tvan, Saddle precipitation, and incoming shortwave radiation measured from the AmeriFlux tower site (US-NR1) from 2008-2013. Wintertime precipitation inputs were modified to approximate average snow depth for each vegetation community observed across the Saddle grid. Land models, like CLM, provide a cohesive framework to investigate biogeophysical and biogeochemical effects of environmental change on ecosystem processes. We used CLM4.5 to investigate if a global-scale model can represent local-scale patterns of water, energy, and carbon fluxes in a heterogeneous mountain environment. Specifically, we were interested in generating testable projections of potential ecosystem responses to climate change. Model output includes half-hourly data on fluxes of energy, water, and carbon, as well as vegetation carbon stocks and edaphic conditions. We also conducted sensitivity analyses to look at ecosystem responses to modifications intended to extend growing season length by decreasing snow albedo and warming air temperatures (black sand and M-A warm, respectively). Information on the variables, units, and data are included as attributed in the network Common Data Form (NetCDF) files for this dataset. For users unfamiliar with using NetCDF files, we have included R scripts that write (forcing data) and read (model output) .nc files include in this data archive. More information about NetCDF files is available at http://www.unidata.ucar.edu/software/netcdf/docs/index.html.

Litter and root decomposition data for Saddle, 1993 - 1994.

Plant tissues, foliage, and roots were collected from Niwot Ridge tundra species and composited into separate 2-gm samples. Foliage was placed in 10x20 cm litter bags with a 2mm^2 mesh to allow entry of invertebrates. Root tissues were placed in 10x20 cm^2 polyester fabric bags to prevent loss of fine root particulates. The foliage litter bags were placed on the tundra surface and secured by 10-penny nails. Root bags were buried in slits 15 cm deep. Each of the 18 1-m^2 research plots, consisted of 2 rows of 5 surface litterbags each. The upper row (with respect to slope) served as the control. The lower row was treated with ammonium nitrate at a rate of 20 g per m^2. Nitrogen will be applied at 3 monthly intervals during each of the growing seasons for the duration of the study. Litter bags (1 surface and 1 buried from each control and treatment) were collected from each plot on 18 September 1993. Additional collections were scheduled to be made in spring and fall of 1994 and spring of 1995. The samples were to be analyzed for changes in total mass, N concentration, and variation in C fractions.

Polygonum bistorta N uptake and storage data for Saddle, 1994.

The patterns of luxury consumption and storage of nitrogen were studied in the rhizomatous alpine herb, Polygonum (Bistorta) bistortoides (Pursh.). Emphasis was placed on understanding the mechanisms, carbon costs, and possible benefits to growth of assimilating and storing excess nitrogen. Nitrogen pools in the rhizome and shoot were measured in fertilized and non-fertilized plants over two growing seasons (the 3rd and 4th growing seasons after initiation of fertilization). Fertilized plants stored more N in the rhizome throughout both seasons and exhibited greater mobilization of N reserves to support growth, compared to non-fertilized plants. Flower, foliar, and preformed bud N concentrations and biomass production rate did not increase in response to fertilization. The increased storage of N without a concomitant influence on biomass production demonstrates that luxury consumption occurs in this species. Fertilized plants relied more heavily on stored N to drive seasonal growth, with translocation from reserves accounting for 56% and 100% of the aboveground N requirement in non-fertilized and fertilized plants, respectively. In fertilized plants, the complete reliance on stored N indicates that the increase in utilization of N from reserves is accompanied by a decrease in utilization of N from current-season uptake. Total plant N content in fertilized plants did not change throughout the entire growing season, demonstrating the absence of net N uptake from the soil. Thus, the uptake and storage of excess N was accompanied by negative feedback to further soil N uptake. Such feedback would constrain the continued accumulation of excess N and eliminate any long term benefits of luxury N uptake in this species. Increased N storage in fertilized plants was accommodated by an increase in the amino acids arginine, the non-protein amino acid, delta-acetyl-ornithine, glutamine, and glutamate. It was found that the entire length of the rhizome, including tissues that are

openCC (other)Sep 2021View details →

25cm NDVI data from UAV campaign at Niwot Ridge Saddle Catchment, 2017

Data collected as part of unmanned aerial vehicle (UAV)/drone campaign during Summer 2017. Investigating snow depth variability and spatiotemporal variations and controls on vegetation productivity within the Niwot Ridge LTER Saddle Catchment.

openCC (other)Apr 2021View details →

Saddle catchment vegetation cover for Distributed Hydrology Soil Vegetation Model (DHSVM), 2 meter, 2019

The Saddle Catchment of the Niwot Ridge LTER is subject to observed and modeled hydrologic connectivity and nuances that is influenced by the variable vegetation across the area. This file was specifically intended to update the Distributed Hydrology Soil Vegetation Model (DHSVM) input file used to simulate vegetation within the Saddle Catchment, as an ongoing method for evaluating modeled hydrologic connectivity. Thus, high resolution vegetation information was used from existing National Ecological Observatory Network (NEON) datasets. NEON has developed a suite of vegetation datasets including a 1m spatial resolution Airborne Observation Platform (AOP) Total Biomass data product. This product is an orthorectified (UTM projection) raster product derived from NEON AOP Imaging Spectrometer (NIS) reflectance data (DP3.30016.001). This vegetation layer was chosen because it visually reflected the differences in vegetation across the Saddle Catchment at a much higher resolution than previous DHSVM vegetation files. Using this gridded biomass product, different vegetation types were manually assigned and translated into to DHSVM vegetation types/codes. The assigning and translating of vegetation types was done by consulting NWT LTER individuals who specialize in the vegetative and soil properties within the Saddle Catchment and using available point-vegetation data from the Saddle Catchment sensor node network. The final product was upscaled to a 2m resolution using R (to match all other DHSVM input files).

Climate and N flux data for Saddle, 1992 - 1995.

Atmospheric gaseous nitric acid (HNO3) plus particulate matter nitrate (NO3) and ammonium (NH4) concentrations were being measured at the Saddle site on an approximately biweekly basis during the winter and on a weekly to twice-weekly basis from April through September. These N species are the dominant contributors to atmospheric N loading at the Saddle site alpine tundra. A 47-mm filter pack with a teflon front filter for NO3 and NH4 collection followed by a nylon filter for HNO3 collection is used to sample the ambient air for 3 to 6 hr. Subsequent colorimetry analysis, performed at the MRS Kiowa Laboratory, is used to obtain the mass of HNO3, NO3, and NH4 on each filter. Air concentrations are then determined by dividing masses by the volume of air sampled.

openCC (other)Oct 2018View details →

Soil chemical and physical property data for Saddle nodal plots, 1986.

Samples were collected from various soil horizons during installation of tension soil solution samplers adjacent to nodal plots in the Saddle. Excavation was limited to minimize disturbance. Consequently, complete soil profile descriptions were not made. Samples were analyzed in the laboratory for various constituents.

Soil methane flux, temperature, moisture, C, and N data for South of saddle, 1991.

Methane emissions were measured from dry and wet meadow plots established by W. Bowman in the Boulder watershed south of the Saddle. The effects of N and P fertilization were evaluated.

Soil methane flux data for Saddle, 1992.

Trace gas samples were collected from 3 alpine tundra vegetation community types (dry meadow, moist meadow, wet meadow) on Niwot Ridge saddle during the summer months of 1992 and 1993 (this data set contains data only from 1992). In addition, samples were collected from a set of control and nitrogen amended plots in both dry and wet meadow community types. Soil temperatures were measured in conjunction with the trace gas sampling. Methane fluxes were calculated from the gas concentration data.

Soil and microbial N data for Saddle, South of saddle, and North of saddle, 1991 - 1992.

Net nitrogen mineralization, nitrification, and microbial nitrogen were measured in dry, moist, and wet meadow plots in 3 different locations on Niwot Ridge: a south-facing slope in the Boulder watershed, across the Saddle, and a north-facing slope. Measurements were made on a monthly basis while soils were unfrozen and once over the period of frozen soil conditions. Associated soil measurements included moisture, temperature, organic N and C, total P, and texture.

openCC (other)Nov 2019View details →

Soil moisture and nutrient data for Saddle grid, 1990.

Soil samples from a 10-cm depth were collected at each vegetated grid stake on the Saddle. These samples were analyzed for carbon and organic matter content. Texture, pH, moisture, and bulk density were also determined. The samples were collected in 1990 and were analyzed at the Soil Testing Laboratory at Colorado State University and at the INSTAAR sedimentology laboratory.

openCC (other)Oct 2018View details →

Air temperature and solar radiation data for Saddle data logger (DP211), 1990 - 2006.

Climatological data were collected from a Niwot Ridge climate station (Saddle) throughout the year using an Omnidata DP211 datapod. This instrument has a sample interval of 5 minutes and records averages of those 5-minute readings every 2 hours. Thus, daily totals represent totals of 288 values. Parameters measured were air temperature (averages) and solar radiation (totals).

Climate data for Saddle chart recorder, 1982 - 1988.

Climatological data were collected from a Niwot Ridge climate station (Saddle at 3525 m) throughout the year. Parameters measured were temperature, relative humidity, solar radiation, wind speed, and run of wind. The station was instrumented with a thermohygrograph (regularly calibrated and checked with maximum and minimum thermometers and psychrometers), which was equipped with a Bourdon tube (to measure temperature) and a banjo-spread hair element (to measure relative humidity). The thermohygrograph was situated in a white, all wood, louvered Stevenson screen which was oriented with the door facing north. Solar radiation was recorded on a bimetalic strip mechanical actinometer. Ninety percent of solar radiation from 360 to 2000 nm was transmitted through the instrument's glass dome. Wind speed (peak gust) was measured near T-Van (3440 m), at a location approximately 400 m south of the Saddle climate station, with a 3-cup, AC-generating anemometer that continuously recorded onto an Esterline Angus strip chart recorder. Run of wind was measured with a Belford totalizing cup anenometer with a counter (at a height of approximately 3 meters above ground) and was located near T-Van as well. Average wind speed was calculated from the peak gust trace. The thermohygrograph, and actinometer both used wind-up or battery-driven clock drives that rotated the recording chart on a right cylindrical drum with a fixed period between 24 h and 861 h depending on the gears used. These clock mechanisms were virtually identical and therefore completely interchangeable among the instruments.

openCC (other)Dec 2018View details →

Aboveground biomass data for Saddle nodal plots, 1982 - 1990.

Estimates of annual primary productivity were made from clip harvests taken within 10 permanently marked plots representing five plant communities. The names of the plant communities (noda) and the associated plot numbers were as follows: fellfield (1 and 12), dry meadow (2 and 11), moist meadow (3 and 10), wet meadow (7 and 9), and snowbed (16 and 19). Maps showing the location of these plots can be found in the JFREA plant laboratory hard copy filing cabinet. Harvested material was separated into 8 above-ground standing crop and 4 composite fractions and weighed.

Aboveground biomass data for Saddle grid plots, 1992 - 1995 and 1997.

During the summer of 1992 10-m transects were established at each of the Niwot Ridge Saddle grid points, with the exception of grid points 1, 13, 30A, 37, 41, 42, 63, and 71. No transects were set up at those locations because they were essentially barren of vegetation or, in the case of grid point 37, were covered with a willow shrub thicket. Transect locations were chosen so that the vegetation along the transect would be consistent with that in the 1x1-m plot used to characterize the species composition at the corresponding Saddle grid point. These transects were established as part of a study designed to quantify any relationship between spectral emissivity and net primary productivity. Spectral measurements were made, using a PS-II (Analytical Spectral Devices) spectrometer (metadata in saddsrad.cw.meta.txt), of approximately 50- x 20-cm plots along a transect immediately prior to it being clip harvested for aboveground biomass determinations. Photographs were taken at the same time that the spectral measurements were made in 1994, but at different times in 1993. The photographs were subsequently used to quantify various cover classes for the harvested portion of the transect (metadata in sadpcovr.cw.meta.txt).