skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Point-Quarter Distance and Dimension Measurements to Calculate Shrub Density and Estimate Shrub ANPP in a Chihuahuan Desert Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico
Title: Point-Quarter Distance and Dimension Measurements to Calculate Shrub Density and Estimate Shrub ANPP in a Chihuahuan Desert Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico
In an effort to better quantify NPP of Creosotebush in the Five-Points region, it was decided to test the Point-Quarter method against the standard 1-m2 quadrat method that has been in use since 1998. Transects were laid out across the 5 mammal trapping webs as well as across burned and unburned plots of the Mixed Shrub site (MS). Repeated measures of the same bushes are performed seasonally. Whole shrubs of various size classes are collected, sorted, and weighed to develop regressions for biomass. Purpose: Data was collected initially to determine density and dimensions of creosote bush in the Five points area on core rodent webs and on burned and unburned plots following the 2003 prescribed burn. It was decided to expand the project by continuing measurements through time to quantify the change in shrub size and with simultaneous harvest of shrubs to measure NPP.  more » « less
Award ID(s):
1655499
PAR ID:
10424118
Author(s) / Creator(s):
;
Publisher / Repository:
Environmental Data Initiative
Date Published:
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, AoB PLANTS)
    Mitchell, Patrick (Ed.)
    Abstract In highly disturbed environments, clonality facilitates plant survival via resprouting after disturbance, resource sharing among interconnected stems and vegetative reproduction. These traits likely contribute to the encroachment of deep-rooted clonal shrubs in tallgrass prairie. Clonal shrubs have access to deep soil water and are typically thought of as relatively insensitive to environmental variability. However, how leaf physiological traits differ among stems within individual clonal shrubs (hereafter ‘intra-clonal’) in response to extreme environmental variation (i.e. drought or fire) is unclear. Accounting for intra-clonal differences among stems in response to disturbance is needed to more accurately parameterize models that predict the effects of shrub encroachment on ecosystem processes. We assessed intra-clonal leaf-level physiology of the most dominant encroaching shrub in Kansas tallgrass prairie, Cornus drummondii, in response to precipitation and fire. We compared leaf gas exchange rates from the periphery to centre within shrub clones during a wet (2015) and extremely dry (2018) year. We also compared leaf physiology between recently burned shrubs (resprouts) with unburned shrubs in 2018. Resprouts had higher gas exchange rates and leaf nitrogen content than unburned shrubs, suggesting increased rates of carbon gain can contribute to recovery after fire. In areas recently burned, resprouts had higher gas exchange rates in the centre of the shrub than the periphery. In unburned areas, leaf physiology remained constant across the growing season within clonal shrubs (2015 and 2018). Results suggest single measurements within a shrub are likely sufficient to parameterize models to understand the effects of shrub encroachment on ecosystem carbon and water cycles, but model parameterization may require additional complexity in the context of fire. 
    more » « less
  2. ; ; (, Global Change Biology)
    Abstract The expansion of shrubs across the Arctic tundra may fundamentally modify land–atmosphere interactions. However, it remains unclear how shrub expansion pattern is linked with key environmental drivers, such as climate change and fire disturbance. Here we used 40+ years of high‐resolution (~1.0 m) aerial and satellite imagery to estimate shrub‐cover change in 114 study sites across four burned and unburned upland (ice‐poor) and lowland (ice‐rich) tundra ecosystems in northern Alaska. Validated with data from four additional upland and lowland tundra fires, our results reveal that summer precipitation was the most important climatic driver (r = 0.67,p < 0.001), responsible for 30.8% of shrub expansion in the upland tundra between 1971 and 2016. Shrub expansion in the uplands was largely enhanced by wildfire (p < 0.001) and it exhibited positive correlation with fire severity (r = 0.83,p < 0.001). Three decades after fire disturbance, the upland shrub cover increased by 1077.2 ± 83.6 m2 ha−1, ~7 times the amount identified in adjacent unburned upland tundra (155.1 ± 55.4 m2 ha−1). In contrast, shrub cover markedly decreased in lowland tundra after fire disturbance, which triggered thermokarst‐associated water impounding and resulted in 52.4% loss of shrub cover over three decades. No correlation was found between lowland shrub cover with fire severity (r = 0.01). Mean summer air temperature (MSAT) was the principal factor driving lowland shrub‐cover dynamics between 1951 and 2007. Warmer MSAT facilitated shrub expansion in unburned lowlands (r = 0.78,p < 0.001), but accelerated shrub‐cover losses in burned lowlands (r = −0.82,p < 0.001). These results highlight divergent pathways of shrub‐cover responses to fire disturbance and climate change, depending on near‐surface permafrost and drainage conditions. Our study offers new insights into the land–atmosphere interactions as climate warming and burning intensify in high latitudes. 
    more » « less
  3. ; ; ; ; (, Environmental Data Initiative)
    {"Abstract":["In 2003, the U.S. Fish and Wildlife Service conducted a prescribed\n burn over a large part of the northeastern corner of the Sevilleta\n NWR. This study was designed to look at the effect of fire on\n above-ground net primary productivity (ANPP) within different\n vegetation types. Net primary production (NPP) is a fundamental\n ecological variable that measures rates of carbon consumption and\n fixation. Estimates of NPP are important in understanding energy\n flow at a community level as well as spatial and temporal responses\n to a range of ecological processes. While measures of both below-\n and above-ground biomass are important in estimating total NPP, this\n study focuses on above-ground net primary production (ANPP).\n Above-ground net primary production (ANPP) is equal to the change in\n plant mass, including loss to death and decomposition, over a given\n period of time. To measure this change, ANPP is sampled twice a year\n (spring and fall) for all species in each of three vegetation types.\n In addition, volumetric measurements are obtained from adjacent\n areas to build regressions correlating biomass and volume. Three\n vegetation types were chosen for this study: mixed grass (MG), mixed\n shrub (MS) and black grama (G). Forty permanent 1m x 1m plots were\n installed in both burned and unburned sections of each habitat type.\n The core black grama site included in SEV129 was incorporated into\n this dataset as an unburned control, so an additional unburned G\n site was not created. The data for this site is noted as site=G and\n treatment=C (i.e., control). The original mixed-grass unburned plot\n caught fire unexpectedly in the fall of 2009 and was subsequently\n moved to the south. Volumetric measurements are made using\n vegetation data from permanent plots collected in SEV156, "Burn\n Study Sites Quadrat Data for the Net Primary Production Study"\n and regressions correlating biomass and volume constructed using\n seasonal harvest weights from SEV157, "Net Primary Productivity\n (NPP) Weight Data.""]} 
    more » « less
  4. (, NSF Arctic Data Center)
    Stem counts of tall shrubs (height from 0.3 to greater than 2 meters) during 2019, 2020, 2021 and 2022 as sampled within n = 594 5-meter radius plots (area = 78.5 square meters), each centered on a selected white spruce adult called "Focal Tree". The purpose of this dataset was to examine spatial variation in tall shrub densities of the most important genera across the Brooks Range and in relation to local microclimates. It also provides a baseline for future shrub stem counts to determine changes in abundance. 
    more » « less
  5. ; ; ; ; (, Environmental Data Initiative)
    {"Abstract":["In 2003, the U.S. Fish and Wildlife Service conducted a prescribed\n burn over a large part of the northeastern corner of the Sevilleta\n National Wildlife Refuge. Following this burn, a study was designed\n to look at the effect of fire on above-ground net primary\n productivity (ANPP) (i.e., the change in plant biomass, represented\n by stems, flowers, fruit and foliage, over time) within three\n different vegetation types: mixed grass (MG), mixed shrub (MS) and\n black grama (G). Forty permanent 1m x 1m plots were installed in\n both burned and unburned (i.e., control) sections of each habitat\n type. The core black grama site included in SEV129 is used as a G\n control site for analyses and does not appear in this dataset. The\n MG control site caught fire unexpectedly in the fall of 2009 and\n some plots were subsequently moved to the south. For details of how\n the fire affected plot placement, see Methods below. In spring 2010,\n sampling of plots 16-25 was discontinued at the MG (burned and\n control) and G (burned treatment only) sites, reducing the number of\n sampled plots to 30 at each.To measure ANPP (i.e., the change in\n plant biomass, represented by stems, flowers, fruit and foliage,\n over time), the vegetation variables in this dataset, including\n species composition and the cover and height of individuals, are\n sampled twice yearly (spring and fall) at each plot. The data from\n these plots is used to build regressions correlating biomass and\n volume via weights of select harvested species obtained in SEV157,\n "Net Primary Productivity (NPP) Weight Data." This biomass\n data is included in SEV185, "Burn Study Sites Seasonal Biomass\n and Seasonal and Annual NPP Data.""]} 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email