Disturbance from fire can affect the abundance and distribution of shrubs and grasses in arid ecosystems. In particular, fire may increase grass and forb production while hindering shrub encroachment. Therefore, prescribed fires are a common management tool for maintaining grassland habitats in the southwest. However, Bouteloua eriopoda (black grama), a dominant species in Chihuahuan Desert grassland, is highly susceptible to fire resulting in death followed by slow recovery rates. A prescribed fire on the Sevilleta National Wildlife refuge in central New Mexico in 2003 provided the opportunity to study the effects of infrequent fires on vegetation in this region. This study was conducted along a transition zone where creosote bushes (Larrea tridentata) are encroaching on a black grama grassland. Before and after the fire, above ground plant productivity and composition were monitored from 2003 to present. Following the prescribed fire, there were fewer individual grass clumps and less above ground grass cover in burned areas compared to unburned areas. This decrease in productivity was primarily from a loss of B. eriopoda. Specifically, B. eriopoda density and cover were significantly lower following the fire with a slow recovery rate in the five years following the fire. Other grasses showed no such adverse response to burning.
To study the effects of infrequent fires on shrub invasion in Chihuahuan desert grassland.
The Sevilleta National Wildlife Refuge is in Socorro County in central New Mexico. The Refuge is along a transition zone between several biomes: Great Plains Grassland, Colorado Plateau, and Chihuahuan Desert. The Burnx study is along a transition zone in the Chihuahuan Desert where the creosote shrubland is encroaching on the black grama grassland. Burnx plots are specifically located on the southern side of McKenzie Flats approximately 2 km southeast of Five Points. GPS coordinates for the Burnx study are: Datum: NAD-27 Latitude: 34 18' 18.0" N Longitude: 106 41' 09.6" W
Locating Permanent Quadrats:
Each replicate plot is 300 m x 300 m and contains a standard Sevilleta mammal trapping web which consists of 12 transects radiating from a central point. Each transect contains 12 numbered stakes for a total of 144 sample points per web. Vegetation is sampled in permanently located 50 cm x 50 cm quadrats at four evenly spaced points along each radius of each web transect (48 permanent quadrats per replicate). The end of each transect is marked with a long rebar stake with smaller rebar stakes occurring in 10 m increments towards the center of the web. Vegetation is measured in only the first four even numbered stakes from the end of the transect on the trapping web. For example, stakes 12, 10, 8, and 6 are measured for the transect that ends with stake 12.
Vegetation is measured in the spring and fall each year. Spring measurements are taken in May when spring annuals have fully matured; and fall measurements are taken in September or October when summer annuals have fully matured and perennial species have reached their peak biomass for the year before the frost.
One corner of a 50 cm x 50 cm quadrat is placed over the sampling stake with the diagonal of the quadrat pointing to the center of the web. The quadrat is placed on the inside of the stake relative to the center point. Cover measurements are taken with a quadrat that is divided in 10 cm x 10 cm sections. Cover of each species rooted in each quadrat is visually estimated in 1% intervals from 1-9%, then in 5% intervals from 10-100%. If a species has a cover less < 1%, the cover is recorded as 0.1%. Only annual plant species are measured in the spring while in the fall both annual and perennial species are measured.
Data are recorded using a palmtop computer. Either a template for Burnx is already on the palmtop or a template must be created by the user. The template has the following fields: Date, Plot, Quad, Spp, Cover and Comments. Open or create Burnx template; save a file on the palmtop with the following format: burnx.mm.dd.yy.initinit. For example, if data was collected on May 13, 2008 by TK the file name would be burnx.05.13.08.tk.
Burnx plots were established in 1991 to study the effects of both fire and antelope disturbance. During the summer of 1993, a prescribed fire was applied to half of the fenced plots and half of the unfenced (open) plots. Therefore, the Burnx study includes four replicates of the following treatments: burned fenced (BF), burned open (BO), control fenced (CF), and control open (CO). In addition, a prescribed fire in 2003 was administered on two of the replicates (3 and 4) for all four treatments.
Data were entered on a palmtop in the field. These files were then downloaded onto the server. The files were run through a perl script and visually assessed for errors. Earlier data were collected on paper and entered into an excel file. These data were checked row by row for any errors. 4 March 2009 tlk Data were qa/qced and obvious errors were corrected. 11 January 2010 tlk
Data were qa/qc'd and errors corrected. Data was them imported into MySQL database.- A.Swann 14 November 2011
Data were qa/qced and obvious errors were corrected. 11 January 2010 tlk
Additional Information on the personnel associated with the Data Collection/Data Processing:
Mike Friggens 1999-September 2001
Karen Wetherill February 7, 2000-August 2009
Terri Koontz February 2000-August 2003 August 2006-Present
Shana Pennington February 2000-August 2000
Heather Simpson August 2000-August 2002
Chris Roberts September 2001-August 2002
Caleb Hickman September 9, 2002-November 15, 2004
Seth Munson September 9, 2002-June 2004
Maya Kapoor August 9, 2003-January 21, 2005
Tessa Edelen August 15, 2004-August 15, 2005
Charity Hall January 31, 2005-January 3, 2006
Yang Xia January 31, 2005-August 2009
Michell Thomey September 3, 2005-August 2008
Jay McLeod January 2006-August 2006
Amaris Swann August 25, 2008-January 2013
John Mulhouse August 2009-Present
Amanda Boutz August 2009-2010
Maya Kapoor April 2010-August 2010
Stephanie Baker October 2010-Present
Megan McClung April 2013-Present