relative abundance

PBG08 Grasshopper density survey in the Patch-Burn Grazing experiment at Konza Prairie

Abstract: 

PBG datasets are associated with a long-term, large-scale study that is addressing the effects of fire-grazing interactions in the context of a Patch-Burn Grazing management system designed to promote grassland heterogeneity. Effects of patch-burn grazing management on plant and animal diversity and the nature and variety of wildlife habitat are being assessed in two replicate management units, each consisting of three pastures (watersheds) designated C03A/C03B/C03C and C3SA/C3SB/C3SC. In each patch-burn grazing unit, one watershed is burned and two that are left unburned in a given year. The burning treatments are rotated annually so that each pasture is burned every third year. Each patch-burn grazing unit is paired with an annually-burned pasture for comparison with traditional grazing systems (C01A and C1SB). All grazing units are stocked with cow/calf pairs from approximately 1 May until 1 Oct at a stocking density equal to 3.2 ha per cow/calf. To examine the impact of patch burning and grazing in all 8 units, we monitor changes in plant species composition, residual biomass, grassland bird populations, insect populations, small mammal populations, soil nutrients, and stream water quality1 (1C3SA/C3SB/C3SC unit only). The KSU Department of Animal Science monitors cattle performance, including weight gain and body condition to assess the economic feasibility of using patch-burn management on a widespread basis. This data set focuses on measuring grasshopper density using ring count method (Onsager 1977*) at watersheds C03A, C03B, C03C, C01A, C3SA, C3SB, C3SC, and C01B. Grazing intensity is estimated (Joern 2005) at each site at time of density measurements to model how grasshopper populations respond to grazing.

Core Areas: 

Data set ID: 

122

Short name: 

PBG08

Purpose: 

To estimate grasshopper densities in the patch-burn grazing experiment.

Methods: 

Location of Sampling Stations: Grasshopper density is determined on upland topographic location. C3A, C3B, C3C, C1A, C3SA, C3SB, C3SC, C1B

Frequency of SamplingGrasshopper densities are sampled once in late Fall (August-September).

Variable Measured: Grasshopper density.

MethodsThree watershed units (C3A, C3B, C3C) constitute 'patches' that are alternately burned in a 3-year rotation within a single, fenced pasture (i.e., patch-burn grazing). Two additional watersheds are serving as controls: a grazed, annually/uniformly-burned watershed (C1A) and an ungrazed, annually/uniformly-burned watershed (1D). At each site, grasshopper densities are sampled using the ring count method (Onsager 1977*), a standard technique for estimating grasshopper densities. Twenty quadrats (0.1 m2) are placed along four transects at each site (80 quadrats per site) and left in place for a minimum of 5 hours. Then, grasshopper densities are counted by slowly approaching each ring and counting the number of grasshoppers within each ring.

*Onsager J.A. (1977). Comparison of 5 methods for estimating density of rangeland grasshoppers (Orthoptera: Acrididae). Journal of Economic Entomology. 70: 187-190. DOI: 10.1093/jee/70.2.187

For additional metadata information see: http://lter.konza.ksu.edu/sites/default/files/DC.pdf

For additional methods information see: http://lter.konza.ksu.edu/sites/default/files/MM.pdf

Data sources: 

Maintenance: 

ongoing

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