Frequency grid—a simple tool for measuring grassland establishment

Abstract

Simple, reliable tools are needed by land managers to quantify establishment success when seeding or re-seeding pastures or rangeland. A frequency grid was designed to measure seedling or plant establishment success for a single species, mixtures of species, or single species of a mixture. The frequency grid is a metal frame containing 25 squares (5 x 5) or cells and can be made from concrete reinforcing sheets that have 15 x 15 cm squares. When used, the frequency grid is either randomly or systematically placed within a seeded area. The number of cells containing 1 or more seeded plants are counted. The grid is then flipped, end-over-end, and the counts are repeated. The process is repeated until a total of 100 cells have been counted per sampling location within a seeded area. Counts can be directly converted into frequency of occurrence or stand percentages by dividing the number of cells that contain a seeded plant by 100. The process can be repeated at several locations within a seeded area to characterize establishment success. Multiplying frequency of occurrence percentages by 0.4 provides a conservative estimate of plant density (plants m -2 ). A single measurement of 100 frequency grid cells can be taken in less than 5 minutes. The frequency grid is inexpensive to make, requires minimal training, permits rapid measurements, and provides a meaningful estimate of plant density. The frequency grid has been used to document herbicide efficacy and seeding rates for use in grassland establishment in the central Great Plains and should be easily adaptable for use in other geographic regions.Key Words: planting, rangeland, pasture, plant density, seedling counts Millions of hectares of land have been seeded to grasslands in the Great Plains and other western states. Additional land will likely be seeded in the future to convert marginal cropland to grasslands, upgrade existing seeded grasslands, and to restore degraded rangeland invaded by noxious weeds or damaged by fires. In addition, millions of hectares of pastures are periodically seeded in humid grassland areas worldwide. After each establishment attempt, the questions that managers must answer include: Was the seeding successful? Is the stand adequate for the intended purpose? If not, do only portions of the seeded area need to be planted again? Because of these questions, managers need tools to quantify the success of grassland plantings and not be forced to rely on visual evaluations.The goal of all grassland re-vegetation is to obtain an acceptable number of established plants of the desired, seeded species per unit of land (i.e., density) which is often expressed as plants m -2 . To be of most value, the plant density measurement also should provide an estimate of plant distribution over the unit area. Methods that have been developed to determine plant density and species composition in grasslands include density per quad- ResumenLos manejadores de tierras necesitan herramientas simples y confiables para cuantificar el éxito del estable...

Strategic use of native species on environmental gradients increases diversity and biomass relative to switchgrass monocultures

“…Thus, after two years, basal area at the shoulderslope and midslope positions in this experiment resembled basal area of historic Tallgrass Prairie, as measured by Weaver (1954) (Table 4). Most estimates of success of establishment for seeded stands of native grasses utilize plants per unit area (Cornelius, 1944) or frequency of grid cells occupied by at least 1 tiller (Vogel and Masters, 2001). Cornelius (1944) determined that 10 plants m À2 the year after planting was a good stand for native warm-season grasses, whereas Schmer et al (2006) determined that a good stand of seeded switchgrass would have at least 1 tiller in 40% of the cells in a grid composed of twenty-five 0.02-m 2 cells in the second year after planting.…”

Efficient Methods of Estimating Switchgrass Biomass Supplies

“…Switchgrass stand frequency was high (>90%) in all plots and across years using a frequency grid [25]. Plots at time of harvest were essentially switchgrass monocultures with greatest amounts of non-planted species occurring in the 0 kg N ha -1 treatment plots.…”

“…Recommendations for stand frequencies are generally listed within an optimum range. Perennial grass stand frequencies less than 25% indicate a partial to unsuccessful establishment; stand frequencies between 25% and 50% indicate marginal to adequate stands, and stand frequencies above 50% indicate a fully successful stand [25]. For switchgrass, an establishment stand threshold above 40% showed no significant differences in post-establishment yields [17].…”

“…A total of 25 sample sites were measured per field in 2003, 2004, and 2005 using GAT and a 0.75×0.75-m frequency grid containing 25 cells [25] in June. Sites were stratified based on cultivar and/or topographic characteristics, then quadrats were randomly located within strata.…”

Sustainability Protocols and Certification Criteria for Switchgrass-Based Bioenergy

“…Sources: Martin et al 1982;Muir et al 2001;Vogel et al 2001;Vogel et al 2002;Hanson et al 2005;Fike et al 2006;Mulkey et al 2006;Cramer et al 2007;Lee et al 2007;Mitchell et al 2008;Mitchell et al 2012;NRDC 2014.…”