ABSTRACT:

These data have been collected at the Reynolds Creek Experimental Watershed by the Northwest Watershed Research Center and the USDA-ARS. Collection began as early as 1962 across these 26 geographically distinct gauge sites. Spatial coordinates, descriptive location names, and other metadata are provided in the header file for each precipitation dataset.

Data columns:
datetime Date & Time (yyyy-mm-dd hh:mm)
ppts Precipitation, Shielded Raingage (mm)
pptu Precipitation, Unshielded Raingage (mm)
ppta Precipitation, Hamon 1971 Dual Gage Wind Corrected (mm)

ABSTRACT:

We describe long term data collected at the Reynolds Creek Experimental Watershed (RCEW) related to below-ground fluxes of energy and water. Soil water content as measured by neutron probe.

These data were collected at locations representing different climates and soils within the RCEW. Spatial variability of water balance within the watershed and well as temporal variability at specific sites is illustrated. High correlation between neutron probe and lysimeter results are the basis for assessing the accuracy of neutron probe-measured changes in soil-water content.

Data columns:
date Date (yyyy-mm-dd)
wat015 Volumetric Water Content at 15 cm (6 in)
wat030 Volumetric Water Content at 30 cm (1 ft)
wat061 Volumetric Water Content at 61 cm (2 ft)
wat091 Volumetric Water Content at 91 cm (3 ft)
wat122 Volumetric Water Content at 122 cm (4 ft)
rel015 Adjusted Volumetric Water Content at 15 cm (6 in)
rel030 Adjusted Volumetric Water Content at 30 cm (1 ft)
rel061 Adjusted Volumetric Water Content at 61 cm (2 ft)
rel091 Adjusted Volumetric Water Content at 91 cm (3 ft)
rel122 Adjusted Volumetric Water Content at 122 cm (4 ft)
pro107 Total Profile Water from Surface to 107 cm depth (cm)
pro137 Total Profile Water from Surface to 137 cm depth (cm)

ABSTRACT:

Snow depth was calculated for the general area of Reynolds Mountain East in Reynolds Creek Experimental Watershed using lidar data collected in November 10-18, 2007 (snow off) and March 19, 2009 (snow on). The raw point clouds were filtered using the BCAL Lidar Tools and then 2007 and 2009 point clouds were georeferenced to each other. The point clouds were then rasterized to 1 m and the 2007 bare earth raster was subtracted from the 2009 snow on raster to create a 1 m snow depth product. (https://bcal.boisestate.edu/tools/lidar and https://github.com/bcal-lidar/tools/wiki/BareDEM).

LiDAR data for Reynolds Creek was acquired by Watershed Sciences, Inc. on March 19th 2009. The total area was 18,532 acres.

Links are provided in the Additional Metadata section below for raw point cloud data (Idaho LiDAR Consortium), and raster products (BSU ScholarWorks).

ABSTRACT:

Lidar-derived raster data collected November 10-18, 2007, including digital elevation model at three (3) meters and five (5) meters; canopy height model at one (1) meter, three (3) meters and five (5) meters and vegetation cover at one (1) meter and five (5) meters.

The lidar survey was conducted by vendor Watershed Sciences, Corvallis, OR. Leica ALS50 Phase II lidar instrument was flown in a Cessna Caravan 208B aircraft over the period of November 10-18, 2007. The data was delivered in LAS 1.1 format with information on return number, easting, northing, elevation, scan angle, and intensity for each return. Point cloud data can be accessed via the Idaho LiDAR Consortium link provided in the Additional Metadata section

A link to BSU ScholarWorks, hosting additional raster products derived from this LiDAR dataset, is provided in the Additional Metadata section. A temporary link to a 3m DEM is also provided in the Additional Metadata section. This raster has been filled and cleaned to remove major artifacts.

ABSTRACT:

These data have been collected at the Reynolds Creek Experimental Watershed by the Northwest Watershed Research Center and the USDA-ARS. Collection began as early as 1977 across five geographically distinct sensor sites at depths ranging from 5-180 cm. Spatial coordinates, descriptive location names, and other metadata are provided in the header file for each soil temperature dataset.

Data columns:
datetime Date & Time (yyyy-mm-dd hh:mm)
stm005 soil temperature at 5 cm depth(°C)
stm010 soil temperature at 10 cm depth (°C)
stm020 soil temperature at 20 cm depth (°C)
stm030 soil temperature at 30 cm depth (°C)
stm040 soil temperature at 40 cm depth (°C)
stm050 soil temperature at 50 cm depth (°C)
stm060 soil temperature at 60 cm depth (°C)
stm090 soil temperature at 90 cm depth (°C)
stm120 soil temperature at 120 cm depth (°C)
stm180 soil temperature at 180 cm depth (°C)

ABSTRACT:

These data have been collected at the Reynolds Creek Experimental Watershed by the Northwest Watershed Research Center and the USDA-ARS. Collection began as early as 1963 across ten geographically distinct sensor sites. Spatial coordinates, descriptive location names, and other metadata are provided in the header file for each streamflow dataset.

Data columns:
datetime Date & Time (yyyy-mm-dd hh:mm)
qcms Calculated Discharge (m^3 s^-1)

ABSTRACT:

Meteorologic measurements are fundamental to the NWRC's mission at Reynolds Creek Experimental Watershed and we have been at it for over 50 years. Air temperature and relative humidity are currently measured at nn sites, precipitation at nn sites, solar radiation at nn sites, and wind speed and/or direction at nn sites.

Data columns:

datetime Date & Time (yyyy-mm-dd hh:mm)
hum3 Relative Humidity Measured ~3 m Above Soil Surface (%)
sol Incoming Solar Radiation (W/m^2)
tmp3 Air Temperature Measured ~3 m Above Soil Surface (°C)
wnd3r Cumulative Wind Run Measured ~3 m Above Soil Surface (km)
wnd3d Instantaneous Wind Direction Measured ~3 m Above Soil Surface (°N)
wnd3sx Maximum Wind Speed Measured ~3 m Above Soil Surface (m/s)
wnd3dr Resultant Mean Wind Direction Measured ~3 m Above Soil Surface (°N)
wnd3sa Mean Horizontal Wind Speed Measured ~3 m Above Soil Surface (m/s)
wnd3sr Resultant Mean Wind Speed Measured ~3 m Above Soil Surface (m/s)
vap3 Water Vapor Pressure Measured ~3 m Above Soil Surface (kPa)
wnd3s Instantaneous Wind Speed Measured ~3 m Above Soil Surface (m/s)

ABSTRACT:

Full waveform lidar data were collected by NASA's Jet propulsion Laboratory (JPL) Airborne Snow Observatory (ASO) in August 2014 for a NASA Terretrial Ecology project (NNX14AD81G). The data were collected using a Riegl LMS Q-1560 dual laser scanner system. The full waveforms were decomposed in Riegl RiPROCESS software to generate 3D point cloud with an average point density of 14-20 pts/m2. The point clouds were corrected for elevation and roll misalignment between adjacent flight lines in TerraScan. A Digital Elevation Model (DEM) of 1 m resolution was derived using the corrected point cloud using BCAL Lidar Tools (https://bcal.boisestate.edu/tools/lidar and https://github.com/bcal-lidar/tools/wiki/BareDEM).

ABSTRACT:

Thirty one years of spatially distributed air temperature, relative humidity, dew point temperature, precipitation amount, and precipitation phase data are presented for the Reynolds Creek Experimental Watershed. The data are spatially distributed over a 10m Lidar-derived digital elevation model at an hourly time step using a detrended kriging algorithm. This dataset covers a wide range of weather extremes in a mesoscale basin (237 km2) that encompasses the rain-snow transition zone and should find widespread application in earth science modeling communities. Spatial data allows for a more holistic analysis of basin means and elevation gradients, compared to point data. Files are stored in the NetCDF file format, which allows for easy spatiotemporal averaging and/or subsetting.

ABSTRACT:

Soil thickness is a fundamental variable in many earth science disciplines but difficult to predict. We find a strong inverse linear relationship between soil depth and hillslope curvature (r2=0.89, RMSE=0.17 m) at a field site in Idaho. Similar relationships are present across a diverse data set, although the slopes and y-intercepts vary widely. We show that the slopes of these functions vary with the standard deviations (SD) in catchment curvatures and that the catchment curvature distributions are centered on zero. Our simple empirical model predicts the spatial distribution of soil depth in a variety of catchments based only on high-resolution elevation data and a few soil depths. Spatially continuous soil depth datasets enable improved models for soil carbon, hydrology, weathering and landscape evolution.

ABSTRACT:

Vegetation biomass estimates across drylands at regional scales are critical for ecological modeling, yet the low-lying and sparse plant communities characterizing these ecosystems are challenging to accurately quantify and measure their variability using spectral-based aerial and satellite remote sensing. To overcome these challenges, multi-scale data including field-measured biomass, terrestrial laser scanning (TLS) and airborne laser scanning (ALS) data, were combined in a hierarchical modeling framework. Data derived at each scale were used to validate an increasingly broader index of sagebrush (Artemisia tridentata) aboveground biomass. First, two automatic crown delineation methods were used to delineate individual shrubs across the TLS plots. Second, three models to derive shrub volumes were utilized with TLS data and regressed against destructively-sampled individual shrub biomass measurements. Third, TLS-derived biomass estimates at 5 m were used to calibrate a biomass prediction model with a linear regression of ALS-derived percent vegetation cover (adjusted R2 = 0.87, p < 0.001, RMSE = 3.59 kg). The ALS prediction model was applied to the study watershed and evaluated with independent TLS plots (adjusted R2 = 0.55, RMSE = 4.01 kg, normalized RMSE = 35%). The biomass estimates at the scale of 5 m is sufficient for capturing the variability of biomass needed to initialize models to estimate ecosystem fluxes, and the contiguous estimates across the watershed support analyzing patterns and connectivity of these dynamics. Our model is currently optimized for the sagebrush-steppe environment at the watershed scale and may be readily applied to other shrub-dominated drylands, and especially the Great Basin, U.S., which extends across five western states. Improved derived metrics from ALS data and collection of additional TLS data to refine the relationship between TLS-derived biomass estimates and ALS-derived models of vegetation structure, will strengthen the predictive power of our model and extend its range to similar shrubland ecosystems.

ABSTRACT:

These data were acquired in October 2015 after the Soda Fire burned approximately 280,000 acres of sagebrush steppe in the northern portion of the Reynolds Creek Experimental Watershed, Owyhee County, Idaho in August of that year. This dataset was collected for Kathleen Lohse, Idaho State University, Department of Biological Sciences, and Mark Seyfried, USDA-ARS Northwest Watershed Research Center. The requested survey area is located approximately 55 km southwest of Boise, ID. The polygon encloses approximately 150 km2.

ABSTRACT:

Soil physical and hydrologic properties were determined on soils ranging from 1425 to 2111 m elevation within the Reynolds Creek Critical Zone Observatory (CZO). Climate varied between elevations, with mean annual precipitation (MAP) from 292 to 800 mm, respectively, and mean annual temperature (MAT) from 9.4 to 5.6 °C. Vegetation was dominated by various sub-species of sagebrush at all sites. Lithology was derived from basalt and Rhyolitic welded tuff at all sites except Johnston Draw, which was derived from granitic parent material. Soils were collected from profiles by genetic horizons down to ~1 m or bedrock. Soil hydraulic properties were determined in the lab using a dew point potentiometer to determine the drier end of the soil water characteristic curves. Estimates of soil water retention and hydraulic conductivity near saturation were determined using a multistep-outflow and evaporation method. Soil bulk densities were also determined, and soil particle size distributions were previously determined (Patton et al. 2017). Using Marquardt-Levenberg type parameter optimization, soil hydraulic parameters for the standard van Genuchten-Mualem water retention and hydraulic conductivity functions were inversely fit. For several rocky subsoils where intact soil cores could not be collected, hydraulic parameters were estimated using a pedotransfer function (RosettaLite v1.1), bracketed using measurements from the nearest soil horizons. Results display subtle increases in soil water storage capacity (1.06%) and effective saturated hydraulic conductivity (~10%) moving from low to high elevations in the watershed. Both alpha (1.9%) and n (1.1%) parameters increased with increasing elevation and rainfall, typical of coarsening soils. In contrast, however, soil particle size distributions had more silt+clay fraction at the highest elevation site. Soil Bulk density was lowest at the high elevation site. Plant available water, determined from weighted average values of field saturated volumentric water content and the water content at the permanent wilting point displayed no trend with elevation or precipitation, suggesting potential tradeoffs in controls on ecohydrological processes with elevation. Not surprising, plant available water was highest in under-shrub soils vs. bare inter-plant patch spaces. In addition, the saturated water holding capacity was greater in surface soils at the low elevation site, with low precipitation, but greater in subsoil horizons at higher elevations with greater precipitation, presumably due to greater eluviation with greater precipitation totals.

ABSTRACT:

The sparse canopy cover and large contribution of bright background soil, along with the heterogeneous vegetation types in close proximity are common challenges for mapping dryland vegetation with remote sensing. Consequently, the results of a single classification algorithm or one type of sensor to characterize dryland vegetation typically show low accuracy and lack robustness. In our study, we improve classification accuracy in a semi-arid ecosystem based on the use of vegetation optical (hyperspectral) and structural (lidar) information combined with the environmental characteristics of the landscape. To accomplish this goal we used both spectral angle mapper (SAM) and multiple endmember spectral mixture analysis (MESMA) for optical vegetation classification. Lidar-derived maximum vegetation height and delineated riparian zones were then used to modify the optical classification. Incorporating the lidar information into the classification scheme increased the overall accuracy from 60% to 89%. Canopy structure can have a strong influence on spectral variability and the lidar provided complementary information for SAM's sensitivity to shape but not magnitude of the spectra. Similar approaches to map large regions of drylands with low uncertainty may be readily implemented with unmixing algorithms applied to upcoming space-based imaging spectroscopy and lidar. As such, widespread studies to develop and understand the nuances associated with these approaches will enable efficient adoption and application.

ABSTRACT:

Detailed hydrometeorological data from the mountain rain-to-snow transition zone are present for water years 2004 through 2014. The Johnston Draw watershed (1.8 km2), ranging from 1497 – 1869 m in elevation, is a sub-watershed of the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho. The dataset includes continuous hourly hydrometeorological variables across a 372 m elevation gradient, on north- and south-facing slopes, including air temperature, relative humidity and snow depth from 11 sites in the watershed. Hourly measurements of solar radiation, precipitation, wind speed and direction, and soil moisture and temperature are available at selected stations. The dataset includes hourly stream discharge measured at the watershed outlet. These data provide the scientific community with a unique dataset useful for forcing and validating models in interdisciplinary studies and will allow for better representation and understanding of the complex processes that occur in the rain-to-snow transition zone.

This version of the data set fixes errors in all data files and supersedes the earlier datasets https://doi.org/10.15482/USDA.ADC/1258769 and https://doi.org/10.15482/USDA.ADC/1245163.

ABSTRACT:

Observations of ecosystem processes across gradients provide invaluable information on the effects of potential shifts in the observed gradient. Ongoing observations from a network of four eddy covariance systems are available to quantify water and carbon fluxes along a climate/elevation gradient within a sagebrush ecosystem. The network is part of the Reynolds Creek Critical Zone Observatory located in southwestern Idaho, USA and contributes to ongoing long-term environmental research and monitoring by the USDA Agricultural Research Service at the Reynolds Creek Experimental Watershed. The sites include a Wyoming big sagebrush site, a low sagebrush site, a post-fire mountain big sagebrush site, and a mountain big sagebrush site located at elevations ranging from of 1425 to 2111 m. Climate variation follows the montane elevation gradient; mean annual precipitation at the sites varies from 290 to 795 mm, and mean annual temperature ranges from is 9.1 to 5.4°C. Annual Gross Ecosystem Production (GEP) for the sites averaged 349, 555, and 814 gC/m2, respectively for the first two years of observation. Annual Net Ecosystem Production (NEP) indicated that the Wyoming big sagebrush site at the lowest elevation was nearly carbon-neutral for 2015, while the other sites had a net flux of 110 to 150 gC/m2 to the ecosystem during the first two years.

ABSTRACT:

This is the AmeriFlux version of the carbon flux data for the site US-Rls RCEW Low Sagebrush. Site Description - The site is located on the USDA-ARS's Reynolds Creek Experimental Watershed. It is dominated by low sagebrush on land managed by USDI Bureau of Land Management.

ABSTRACT:

This is the AmeriFlux version of the carbon flux data for the site US-Rws Reynolds Creek Wyoming big sagebrush. Site Description - The site is located on the USDA-ARS's Reynolds Creek Experimental Watershed. It is dominated by Wyoming big sagebrush on land managed by USDI Bureau of Land Management.

ABSTRACT:

This is the AmeriFlux version of the carbon flux data for the site US-Rms RCEW Mountain Big Sagebrush. Site Description - The site is located on the USDA-ARS's Reynolds Creek Experimental Watershed. It is dominated by mountain big sagebrush on land managed by USDI Bureau of Land Management.

ABSTRACT:

Dryland ecosystems are experiencing more variability and extremes in rainfall and disproportionate shifts in plant community composition, both likely to alter soil carbon (C) cycling and storage. Although most studies focus on changes in soil organic C (SOC) pools, inorganic C (SIC) pools in drylands are susceptible to disturbances and may represent an important sink. We report changes in soil organic carbon (SOC) and inorganic carbon (SIC) isotopic values in the top 1 m of soil profiles following ~20 years of experimental manipulation of water availability and vegetation within a cold-desert ecosystem. The changes in C isotopic values correspond to reported changes in SOC and SIC pools relative to ambient controls. We used a split plot design (n = 3) contrasting vegetation types (split plot), either native Artemisia tridentata spp. tridentata (big sagebrush) communities or monocultures of Agropyron cristatum (crested wheatgrass), a non-native bunchgrass, in manipulations of spring/fall (DORM) or summer (GROW) water availability (whole-plot) all stratified by under-plant vs. inter-plant patch microsite. Despite increases in pedogenic SIC pools in inter-plant patches, under crested wheatgrass in DORM treatments, and under sagebrush in GROW treatments, we detected little corresponding change in SIC-δ13C or δ18O values. Average SIC-δ13C or δ18O values were -4.12 and -13.10‰, respectively, and suggest a mixture of atmospheric and respired carbon dioxide (CO2) sources and groundwater HCO3-. Both SIC and SOC-δ13C values were more depleted in GROW treatments (∆13C = -0.10 and -0.5‰ respectively), while SIC-δ18O values were more enriched (∆18O = 0.02‰). SIC-δ13C profiles became more enriched in surface horizons and deleted at depth relative to ambient. SIC- δ18O values were enriched in surface horizons under crested wheatgrass but not sagebrush. We conclude that both change in the timing and availability of water, and vegetation can change SIC storage and potentially the relative mixture of C sources. However, suitable methods for assessing SIC-C sources with changing storage in native soils are lacking and limit our understanding of SIC in the changing global C budget. Further methodological development is required along with long-term experimental manipulations geared for testing the role of SIC in C sequestration on human timescales.

ABSTRACT:

Dryland ecosystems are experiencing more variability and extremes in rainfall and disproportionate shifts in plant community composition, both likely to alter soil carbon (C) cycling and storage. Despite these trends, we lack long-term experimental data that facilitates predicting shifts in ecosystem function with climate change. This dataset records changes in soil organic carbon (SOC) and inorganic carbon (SIC) storage in the top 1 m of soil profiles following 19 years of experimental manipulation of rainfall and vegetation within a cold-desert ecosystem. A split plot design was employed (n = 3) and included 1) contrasting vegetation types (split plots), either native Artemisia tridentata spp. tridentata (big sagebrush) communities or monocultures of Agropyron cristatum (crested wheatgrass), a non-native bunchgrass, and 2) manipulations of spring/fall or summer rainfall (whole plots). We further stratified the plots by under-plant vs. inter-plant patches. Soil C responses to long-term rainfall treatments varied by vegetation type. Long-term summer rainfall treatments significantly increased both SOC and SIC pools under A. tridentata, with total carbon (TC) pools 1.15 × ambient controls (P = 0.02). Carbon pools in spring/fall rainfall treatments significantly decreased, with TC pools 0.80 × ambient (P = 0.05) due to losses of inorganic carbon. In contrast, A. cristatum increased in SOC but lost SIC in response to both summer and spring/fall rainfall additions, resulting in no change to a slight gain in TC pools (P = 0.29). Both SOC and SIC pools in inter-plant spaces increased with summer rainfall treatments and decreased with spring/fall rainfall regardless of vegetation type. In contrast to most studies that only examine surface soils (0-0.1 m), our findings indicate that increases in cool-season rainfall will cause A. tridentata communities to become a net C source, whereas A. cristatum monocultures may become C sinks – largely due to tradeoffs between SOC and SIC pools. We conclude that consideration of vegetation type, the entire vertical profile, and both organic and inorganic C forms are imperative to predicting responses of dryland ecosystems to changing climate.

ABSTRACT:

Pedotransfer functions (PTFs) have been developed to estimate soil bulk density (BDFF) using the relationships with soil organic carbon content (SOC) and particle size distribution. Current PTF’s implicitly assume that coarse fraction (CF) content and lithology do not influence BDFF. In this study, we examine the influence of CF content and lithology on BDFF estimates by developing PTF’s for total bulk density (BDT), which includes both fine and coarse fragments, using measured SOC in soils derived from felsic and mafic lithologies (148 felsic and 64 mafic, 212 total). Our results show that SOC is highly correlated with BDT in soils derived from felsic (r2 value of 0.79, p2 value of 0.84, p 2 mm), and we adjust BDT with soil pedon CF content to determine fine fraction bulk densities (BDFF-CFadj). A validation subset of 70 samples was used to compare our model against 23 published PTFs. When BDT is corrected for CF, which is highly variable vertically and horizontally within the watershed, we observe substantial improvements (average of 10.05 ± 4.89 %) in BDFF-CFadj estimation and associated errors compared to other PTFs. Findings from our study demonstrate that incorporation of CF and lithology into BDFF estimations can substantially improve BDFF and consequently soil carbon stock estimates.

ABSTRACT:

Soil physical properties, analytical measures and photographs were taken on soils within the Reynolds Creek Experimental Watershed (RCEW), which is an extensively monitored catchment within southwestern Idaho. Samples were collected over a full range of elevation (1187 to 2111 m), vegetation, lithology (granite, basalt, rhyolite, and colluvium), and climate that varies between mean annual temperature (MAT) precipitation (MAP) from 4.7 to 9.2 °C and 233 to 972 mm, respectively. Soils were collected from profiles by genetic horizons and predetermined depth down to ~1 m or mobile-immobile regolith interface. Here, we provide a spatially extensive soil dataset for 93 soil profiles and 560 sub-samples. We make available a complete soil dataset in conjunctions with the System for Earth Sample Registration (SESAR), where all samples have a unique International Geo Sample Number (IGSN).

ABSTRACT:

Reynolds Mountain East (RME) is a small (0.36 km2), extensively monitored catchment within the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho. RME is primarily associated with snow surveys, stream discharge, suspended sediment, and climate measurements; however, many soil profiles have been excavated, described, and analyzed in this catchment. RME has an elevation of ~2100 m, mean annual precipitation (MAP) of ~900 mm/yr, and mean annual temperature (MAT) of ~5.2 ᵒC. Here, we provide a spatially extensive soil dataset for 10 soil profiles and 78 sub-samples with the values of various soil properties and analytical measurements. We make available a complete soil dataset in conjunctions with the System for Earth Sample Registration (SESAR), where all samples have a unique International Geo Sample Number (IGSN).

ABSTRACT:

Soil thickness is a fundamental variable in many earth science disciplines but difficult to predict. We find a strong inverse linear relationship between soil depth and hillslope curvature (r2=0.89, RMSE=0.17 m) at a field site in Idaho. Similar relationships are present across a diverse data set, although the slopes and y-intercepts vary widely. We show that the slopes of these functions vary with the standard deviations (SD) in catchment curvatures and that the catchment curvature distributions are centered on zero. Our simple empirical model predicts the spatial distribution of soil depth in a variety of catchments based only on high-resolution elevation data and a few soil depths. Spatially continuous soil depth datasets enable improved models for soil carbon, hydrology, weathering and landscape evolution.

ABSTRACT:

Mountainous terrain defines many dryland regions and results in pronounced variation in soil thickness and soil organic carbon (SOC) stocks that is not currently captured by carbon and global climate models. Here we quantify how total profile SOC varies with topographic morphometry, aspect and curvature, to estimate SOC storage within a 1.8 km2 granite-dominated catchment in Idaho, U.S.A. We show that north-facing soil pits have on average 2.9 times more total SOC per area than the south-facing sites, and convergent soil pits have on average 6.4 times more total SOC per area compared to divergent sites. Curvature explained 91% of variation in total profile SOC at a 3-m resolution when the entire vertical dimension of SOC was determined. Catchment SOC stocks were determined from this curvature-SOC model and showed that SOC below 0.3 m depth accounted for >50% of the catchment total SOC, indicating substantial underestimation of SOC stocks if only sampled at shallower depths. We conclude that processes responsible for carbon sequestration in soils vary spatially at relatively small scales, and they can be described in a deterministic fashion given adequate elevation data.

ABSTRACT:

Our study used mass flux, particle size distribution and geochemistry to analyze variations in aeolian deposition following the Soda Fire of August 2015 in southwest Idaho.The data presented characterizes the aeolian material deposited in dust traps at a height of 2 meters above the soil surface. Mass data were collected using a microbalance, particle size distributions were analyzed using laser diffractometry, and geochemistry was analyzed using inductively coupled plasma mass spectrometry.

ABSTRACT:

Artemisia spp. play a significant role in hydrological cycling of sagebrush steppe ecosystems. These sagebrush ecosystems cover a wide elevation gradient and are dominated by different species and subspecies of sagebrush. Water balance of sagebrush ecosystems varies along an elevation gradient with pulse-driven ecosystems located at lower elevation and drier sites and water storage (i.e., snow-dominated precipitation) ecosystems located at higher elevation and wetter sites. Thus, it is difficult to predict how water fluxes in these ecosystems will respond to changing climatic conditions along an elevation gradient. The primary objective of this study was to characterize sap flux in three sagebrush communities located along a rain- to snow-dominated regime by comparing hourly, daily, and seasonal sap flux patterns and their relationships with environmental factors. Sap flux was monitored between June 2015 and October 2017 using heat balance sensors. Meteorological data was also measured from adjacent weather stations, including air temperature (Tair), vapor pressure deficit (VPD), solar radiation (SR), and relative humidity (RH). Soil moisture content was also monitored at different depths in three communities during study period. We hypothesized that sap flux would be greater in the shrubs located at the highest, snow-dominated site compared to lower, rain-dominated sites. Our results indicated that daily sap flux was greater (~ 17%) in A.t. wyomingensis at the rain-dominated site (WBS) compared to A.t. vaseyana at the snow-dominated site, likely due to a comparatively longer growing season at the lower site. Sap flux drives several physiological response of desert plants (i.e., gas exchange, water transport, plant hydraulics) and will be impacted by climatic changes. Therefore, accurate estimation of plant water use (i.e., sap flux) and how various environmental factors influence sap flux in different sagebrush communities will help in predicting the role of sagebrush in hydrological cycling in future scenarios.

ABSTRACT:

The SOC (Soil Organic Carbon) pool is a large carbon reservoir that is closely linked to climatic drivers. In complex terrain, quantifying SOC storage is challenging due to high spatial variability. Generally, point data is distributed by developing quantitative relationships between SOC and spatially-distributed, variables like elevation. In many ecosystems, remotely sensed information on above-ground vegetation (e.g. NDVI) can be used to predict below-ground carbon stocks. With this research, we evaluated SOC variability in complex terrain and attempt to improve upon SOC models by incorporating hyperspectral and LiDAR datasets.

ABSTRACT:

Johnston Draw (JD) is a small (1.83 km2), primarily granitic sub-watershed of the Reynolds Creek Experimental Watershed (RCEW) located within the Owyhee Mountain Range in southwestern Idaho, USA. JD is situated on the western portion of the RCEW, primarily oriented east-west, with a mean annual precipitation (MAP) of 550 mm/yr and mean annual temperature (MAT) of 7.4 ᵒC near the outlet. Here, we provide a spatially extensive soil dataset for 45 soil profiles and 228 sub samples over the full range of elevation of 1490-1850 m. Soil profiles have been excavated, described, analyzed for a variety of analytical measurements, and recorded in conjunction with the System for Earth Sample Registration (SESAR), where all samples have a unique International Geo Sample Number (IGSN).

ABSTRACT:

Chamber method was used to compare the ecosystem carbon and water flux among three sagebrush types present along an elevational gradient. Chamber data was also used to model seasonal carbon and water flux based on best environmental parameters. This modeled data was compared with eddy tower data.

ABSTRACT:

Streamflow in arid and semi-arid regions is predominantly temporary but of significant importance for groundwater recharge and biogeochemical processes. However, temporary streamflow regimes remain poorly quantified. We use electrical resistance sensors and USGS stream gauge data to quantify streamflow intermittency as streamflow presence and water presence, which includes streamflow, ponding and soil moisture, in 13 southern Arizona streams spanning a climate gradient (mean annual precipitation from 160 to 750 mm). The monitoring washes were located in largely undisturbed military facilities, long term ecological research areas and a nature preserve. The most arid study washes, Black Gap (BG) and Sauceda Wash (SW), were located within the Barry M. Goldwater Air Force Base near Gila Bend, Arizona in the Lower Gila River Basin. Two semi-arid study washes were located on the Santa Rita Experimental Range near Sahuarita, Arizona in the Santa Cruz River Basin (SS and SR). Nine study sites were located on the Huachuca Mountains near Sierra Vista, Arizona and form part of the San Pedro River Basin. The study sites were located along 3 distinct elevations in 3 canyons: Huachuca Canyon and Garden Canyon which are located within the Fort Huachuca Army Post; and Ramsey Canyon, within the Nature Conservancy’s Ramsey Canyon Preserve. We established three cross-sectional transects 100 m apart at each reach, except Sauceda and Black Gap Washes where there were 5 transects, and installed electrical resistance sensors (TidbiT v2 UTBI-001 data logger, Onset Corporation, Bourne, MA) at the thalweg of each cross-sectional transect to identify surface water presence frequency and duration. The electrical resistance sensors were temperature sensors modified as outlined in Blasch et al. (2002), with 2 electrical leads exposed. We followed the method outlined by Jaeger and Olden (2012) to identify the onset and cessation of runoff. In brief, the onset of runoff is marked by the sudden and rapid increase in the relative electrical conductivity (EC) signal to a less negative or a positive number, while the termination of streamflow is also marked by a similarly sudden shift in the EC signal back to a more negative signal. In this study, EC = -94 indicates dry conditions. We were also able to quantify the duration of surface water presence as moist soil or ponded water because the EC signal for runoff is distinct from that of a moist soil and soil-drying conditions. Raw EC data and derived daily summaries of streamflow and water presence are reported.

ABSTRACT:

The overarching goal of this study is to better understand the relationship between plant carbon (C) and nitrogen (N) isotopic signatures and climate in a sagebrush-steppe ecosystem. Additionally, this study seeks to a) determine how plant isotopic data in the sampled ecosystem compare with global patterns with respect to broader climate gradients; and b) evaluate any additional effects on plant isotopic compositions due to soil attributes (chemical, physical). Climatic effects on C and N isotopes were analyzed by examining plant and soil samples across a climatic gradient within the Reynolds Creek Critical Zone Observatory (RCCZO) (comprised of the USDA ARS Reynolds Creek Experimental Watershed) located in the Owyhee Mountains in southwestern Idaho. Sampling focused on two subwatersheds (Johnston Draw and Whiskey Hills) in July 2015. Soil cores were obtained from both plant and interplant spaces, with a total of 480 samples (120 cores at 4 depth intervals). Samples of plants (n=120) present at each core location were collected at the same time soils were obtained to allow for evaluating relationships between soil and plant processes. At each plant location, samples consist of sagebrush foliar tissue, while samples from interplant plots often consisted of a mixture of grasses and forbs. Soil data include soil moisture, gravimetric water content, soil organic matter, stable carbon and nitrogen isotopes, percent carbon and nitrogen, initial/final/potential nitrate concentration, initial/final/potential ammonium concentration, net nitrification rate, potential net nitrification rate, net mineralization rate, potential net mineralization rate, and pH. Note: the majority of extractions for ammonium concentrations were contaminated so ammonium (and thus mineralization) data is largely unavailable for this study. Plant data includes stable carbon and nitrogen isotopes and percent carbon and nitrogen for sagebrush foliar tissues (perennial leaves only).

ABSTRACT:

Stream drying and wildfire are projected to increase with climate change in the western United States, and both are likely to influence the patterns and processes explaining stream chemistry. To investigate drying and wildfire effects on stream chemistry (carbon, nutrients, anions, cations, and isotopes), we examined seasonal drying in two intermittent streams in southwestern Idaho, one stream that was unburned and one that burned six months prior. We hypothesized that spatiotemporal patterns of stream chemistry would change due to increased evaporation, groundwater dominance, and autochthonous carbon production as water and carbon sources shifted from snowmelt to low flow conditions. With increased nutrients and sunlight available, we expected greater shifts in the burned stream. To capture spatial stream chemistry patterns, we sampled surface water for a suite of analytes in each stream longitudinally with a high spatial scope (50-meter intervals along ~2500 meters). To capture temporal variation during drying, we sampled each stream in April, May, and June (2016). Patterns and processes influencing stream chemistry were generally similar in both streams, but some were amplified in the burned stream. Mean dissolved inorganic carbon (DIC) concentrations increased with drying by 22% in the unburned and by 3-fold in the burned stream. In contrast, mean total nitrogen (TN) concentrations decreased in both streams, with a 16% TN decrease (mostly DON) in the unburned stream and a 5-fold TN decrease (mostly nitrate) in the burned stream. Contrary to expectations, dissolved organic carbon (DOC) concentrations were longitudinally variable but relatively less temporally variant. In addition, we found weak evidence for evapoconcentration with drying. However, consistent with our expectations, both water isotopes and strontium-DIC ratios indicated stream water shifted towards groundwater-dominance, especially in the burned stream. Fluorescence and absorbance measurements showed considerable longitudinal variation in DOC sourcing with seasonal drying in both streams, and temporal shifts from autochthonous to allochthonous carbon sources in the burned stream. Our findings suggest that the effects of fire may magnify chemistry patterns but not the controls with stream drying. This empirical study contributes to advancing our conceptual stream models that incorporate stream drying, wildfire, and the interplay between them.

ABSTRACT:

Soil carbon is the largest terrestrial carbon (C) store but remains a large source of uncertainty in C storage models due to high temporal and spatial variability, and a lack of process understanding. Carbon dioxide (CO2) fluxes are especially difficult in desert ecosystems exhibiting pulses of biogeochemical cycling regulated by antecedent soil conditions. Using the soil CO2 gradient method and measures of soil physical and hydrologic properties, we present a soil respiration model for a cold desert climate and which incorporates antecedent controls on CO2 emissions using Bayesian methods. Soil properties and CO2 measurements between October 2016-2018 were taken from a catchment at 2111 m elevation within the Reynolds Creek Critical Zone Observatory (CZO). Mean annual precipitation is snow-dominated and averages 800 mm. Mean annual temperature is 5.6 °C. Vegetation is dominated by various sub-species of sagebrush. Lithology was derived from basalt and Rhyolitic welded tuff. Soil CO2, soil moisture, and soil temperature sensors at 5 depths within the soil profile recorded every 30 minutes from October 2016 to June 2018. Rates of CO2 efflux and production used modeled soil porosity and hydraulic characteristics to account for changes in diffusivity with variable soil moisture.

ABSTRACT:

This dataset provides surface reflectance measured by the Airborne Visible/Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) instrument during flights over research sites in Idaho and California in 2014 and 2015. AVIRIS-NG measures reflected radiance at 5-nanometer (nm) intervals in the visible to shortwave infrared spectral range between 380 and 2510 nm. Measurements are radiometrically and geometrically calibrated and provided at 1-meter spatial resolution. The data include 72 flight lines covering long-term research sites in the Reynolds Creek Experimental Watershed in southwestern Idaho and Hollister in southeastern Idaho. Several flight lines from a site in the Inyo National Forest near Big Pine, California are included.

ABSTRACT:

Ephemeral and intermittent streams are increasing with climate and land use changes, and alteration in stream water presence or flow duration will likely affect soil nutrient dynamics in channel and riparian zones more than dryland uplands. To investigate the influence of varying climate and stream flow regimes on associated soil nutrient dynamics, we monitored soil moisture and nutrient dynamics over an 18-month period across a range of ephemeral to seasonally- intermittent stream reaches (13) and landscape positions (channel, riparian, upland) in Arizona, USA. The monitoring reaches were located in largely undisturbed military facilities, long term ecological research areas and a nature preserve. The most arid study washes, Black Gap (BG) and Sauceda Wash (SW), were located within the Barry M. Goldwater Air Force Base near Gila Bend, Arizona in the Lower Gila River Basin. Two semi-arid study washes were located on the Santa Rita Experimental Range near Sahuarita, Arizona in the Santa Cruz River Basin (SS and SR). Nine study sites were located on the Huachuca Mountains near Sierra Vista, Arizona and form part of the San Pedro River Basin. The study sites were located along 3 distinct elevations in 3 canyons: Huachuca Canyon and Garden Canyon which are located within the Fort Huachuca Army Post; and Ramsey Canyon, within the Nature Conservancy’s Ramsey Canyon Preserve. We established three cross-sectional transects 100 m apart at each reach, except Sauceda and Black Gap Washes, where there were 5 transects. We measured soil physio-chemical characteristics including bulk density, particle size distribution, % carbon (C) and nitrogen (N) and isotopes. We monitored seasonal soil moisture, soil exchangeable N and phosphorus pools and N transformation rates using both soil extractions and incubations, wet up experiments, as well as in-situ ion exchange resin bags. Site description and soil data are available over an 18 month period and can be associated with decomposition data and streamflow data sets.

ABSTRACT:

Ephemeral and intermittent streams are increasing with climate and land use changes, and alteration in stream water presence or flow duration will likely affect litter decomposition in channel and riparian zones more than dryland uplands. To investigate the influence of varying climate and stream flow regimes on rates of decomposition, we used a space-for-time substitution design and deployed common leaf litter over an 18-month period across a range of ephemeral to seasonally- intermittent stream reaches (10) and landscape positions (channel, riparian, upland) in Arizona, USA. The monitoring reaches were located in largely undisturbed military facilities, long term ecological research areas and a nature preserve. The most arid study washes, Black Gap (BG) and Sauceda Wash (SW), were located within the Barry M. Goldwater Air Force Base near Gila Bend, Arizona in the Lower Gila River Basin. Nine study sites were located on the Huachuca Mountains near Sierra Vista, Arizona and form part of the San Pedro River Basin. The study sites were located along 3 distinct elevations in 3 canyons: Huachuca Canyon and Garden Canyon which are located within the Fort Huachuca Army Post; and Ramsey Canyon, within the Nature Conservancy’s Ramsey Canyon Preserve (one was later dropped owing to a fire). We established three cross-sectional transects 100 m apart at each reach, except Sauceda and Black Gap Washes where there were 5 transects, and installed electrical resistance sensors (TidbiT v2 UTBI-001 data logger, Onset Corporation, Bourne, MA) at the thalweg of each cross-sectional transect to identify surface water presence frequency and duration. Consistent with expectations, rates of litter decomposition (k) decreased significantly in the channels as cumulative percentage (%) of water presence decreased below 40%. Indeed, differences in cumulative duration of water presence as well as channel bed material silt content explained 79% of the variation in k across flow regimes. Collectively, our findings suggest that rates of decomposition in intermittent stream channels will decrease with reduced duration of stream flow and water presence whereas rates in riparian zones will be less responsive to changes in climate and associated subsidies of stream flow.