Cryptogam Crust Data from Long-Term Small Mammal Exclosure Study on the Jornada Experimental Range, 1995-2005

Study number:

Data set ID:

210086003

Data Access:

Unrestricted

Dataset status:

completed

Abstract:

Data sources:

data_JornadaStudy_086_smes_cryptogam_crust

Methods:

Field micro-cassette tape recorders

Each study site is 1 km by 0.5 km in area. Three rodent trapping webs and four replicate experimental blocks of plots are randomly located at each study site to measure vegetation responses to the exclusion of small mammals The blocks of study plots are all oriented on a site in a X/Y coordinate system, with the access road to each site forming the X axis. The compass orientation at the Jornada grassland site is to the north, and Jornada creosotebush site is oriented to the south. Treatments within each block include one unfenced control plot (Treatment: C; control), one plot fenced with hardware cloth and poultry wire to exclude rodents and rabbits (Treatment: R; rodent), and one plot fenced only with poultry wire to exclude rabbits (Treatment: L; lagomorph), and one plot fenced with barbed wire to exclude cattle (Treatment B; bovine). There are cattle exclosure plots only at the Jornada grassland site where cattle are present, for a total of 4 measurement plots at each of the grassland site blocks. There are only 3 measurement plots at each of the creosotebush site blocks. The treatments are randomly assigned to each of the four possible plots in each block independently, and their arrangements differ from block to block. Each of the plots in a replicate block are separated by 20 meters. Each experimental measurement plot measures 36 meters by 36 meters. A grid of 36 sampling points are positioned at 5.8-meter intervals on a systematically located 6 by 6 point grid within each plot. A permanent one-meter by one-meter vegetation measurement quadrat is located at each of the 36 points. All cover values are measured from the vegetation measurement frame, which is 1 meter by 1 meter, and partitioned into a grid of 100, 10 cm by 10 cm squares. Cryptogams include lichen, moss, and algae.Cover is measured by counting the number of 10cm squares that are occupied by the cryptogams. Some cryptogam cover has distinctive margins and is easy to define and measure. However, many cryptogam crusts consist of many diffuse small patches that are separated by bare soil, and distributed throughout the quadrat. For such diffuse cover, the actual cover in one typical 10 by 10 cm square (e.g., 0.3) is determined, then multiplied by the number of squares with diffuse cover (e.g., 5). Cover across all squares is added to make one estimate for the quad. For cover values greater than 5, increments of five are used.

Quality Assurance:

SAS programs was used to analyze data

Additional information:

A creosotebush shrub study site and a black grama grassland study site have been established at each of the Sevilleta, Jornada and Mapimi research locations. Each study site is 1 km by 0.5 km in area. Three rodent trapping webs and four replicate experimental blocks of plots are randomly located at each study site to measure vegetation responses to the exclusion of small mammals. The blocks of study plots are all oriented on a site in a X/Y coordinate system, with the access road to each site forming the X axis. The compass orientation at the Jornada grassland site is to the north, and Jornada creosotebush site is oriented to the south. Treatments within each block include one unfenced control plot (Treatment: C; control), one plot fenced with hardware cloth and poultry wire to exclude rodents and rabbits (Treatment: R; rodent), and one plot fenced only with poultry wire to exclude rabbits (Treatment: L; lagomorph), and one plot fenced with barbed wire to exclude cattle (Treatment B; bovine). Note that there are cattle exclosure plots only at the Jornada grassland site where cattle are present, for a total of 4 measurement plots at each of the grassland site blocks. There are only 3 measurement plots at each of the creosotebush site blocks. The treatments were randomly assigned to each of the four possible plots in each block independently, and their arrangements differ from block to block. Each of the plots in a replicate block are separated by 20 meters. Each experimental measurement plot measures 36 meters by 36 meters (see Figure 4). A grid of 36 sampling points are positioned at 5.8-meter intervals on a systematically located 6 by 6 point grid within each plot. A permanent one-meter by one-meter vegetation measurement quadrat is located at each of the 36 points. The 36 quadrats are numbered 1-36, starting with number 1 in the top left corner of each plot, and running left to right, then down one row, and then right to left, and so on. A 2-foot rebar marks the lower right corner of each quadrat, and an aluminum tag on the rebar gives the quad number. 3-inch nails were originally placed in the top left corner of each quadrat. These may be difficult to see. A 3-meter wide buffer area is situated between the grid of 36 points and the perimeter of each plot. Rodent trapping webs are being used to determine the composition of rodent species at each study site, and to estimate densities of each species over time. The use of webs and distance measures to estimate rodent densities is statistically more robust than grid plot sampling and mark-release indices. Each rodent trapping web consists of a series of 12 equally spaced lines radiating from a central point. Each line consists of 12 trap stations. The first trap station is located 5 meters from the center, the next three at 5 meter intervals, and the remaining 8 at ten meter intervals. Each trap line is 100 meters long, and each web is 200 meters in diameter.