Data Set Summary
| Item | Value |
|---|---|
| Dataset ID: | grubr |
| Dataset Title: | SGS-LTER Disturbance intensity and above- and belowground herbivory effects on long-term recovery of shortgrass steppe on the Central Plains Experimental Range, Nunn, Colorado, USA 1977-1990 |
| Abstract: | The importance of disturbance intensity and herbivory by cattle and white grubs, or the larvae of June beetles to recovery of shortgrass steppe ecosystems in Colorado, USA were evaluated over a 14 year time period. Disturbance intensity was defined by survival of the dominant grass species (Bouteloua gracilis) after an outbreak of root feeding activity by white grubs. 16 patches of vegetation consisting of four pairs of adjacent ungrazed-grazed by cattle locations with 2 replicates that were recently affected by white grubs were selected in 1977. Disturbance intensity was determined in 1977 by the area in each patch that contained live tillers of B. gracilis. Permanent plots were lcoated both within and outside of each patch. Plant basal cover and density by species were estimated at time of peak aboveground biomass in 6 different years on each plot. Successional dynamics on patches was similar to areas affected by other types of disturbances, however, rate of recovery was faster for patches affected by grubs. Grazing by cattle was infrequently important to plant recovery, a result similar to effects of grazing on other aspects of shortgrass steppe. Disturbance intensity was important to recovery of B. gracilis since tiller survival in 1977 was linearly related to cover in each year of sampling. For ungrazed patches, initial conditions were important to recovery of B. gracilis for as many as 14 years. For grazed patches, initial conditions decreased and grazing increased in importance through time. Changes in resource quality and more uniform distribution of roots due to grazing likely resulted in more complete mortality of plants by grubs under grazed compared to ungrazed conditions. Persistance of shortgrass steppe ecosystems in spite of disturbances with different intensities are determined at least in part by characteristics of disturbances interacting with the ability ofplants to respond, and in part by the evolutionary history of the system. Although white grubs affect shortgrass communities infrequently, they have large and important effects on plant community structure through time, and represent an important class of disturbance defined by intensity. |
| Methods: | Vegetation was sampled six times from 1977 to 1990 using permanently marked plots located on 4 transects within each patch and the surrounding undisturbed area. Near time of peak aboveground biomass (July 15 to August 15) in each year (1977, 1978, 1979, 1980, 1982 and 1990), plant basal cover and density by species were estimated using 30cm x 30cm quadrats located on each transect. A similar number of quadrats was used to sampled within the patch (avr = 20 quadrats/patch) compared to the undisturbed vegetation (avg=24 quadrats/area). Basal cover of live perennial plants by species, dead Bouteloua gracilis crown, litter, bare ground, and lichens were visually estimated in each quadrat. Density of annuals was determined by counting individual stems. Tillers of B. gracilis were counted in a 10 cm x 10 cm quadrat placed on a standard location with within large quadrat. |
| Principal Investigator: | Bill Lauenroth |
| Long Term Contact: | Bill Lauenroth: wlauenro@uwyo.edu |
| Public Access Status: | open |
| Begin Date: | 7/31/1977 |
| End Date: | 8/31/1990 |
| Sample Frequency: | |
| Long Term Experiment?: | |
| Keywords: | populations, blue grama, disturbance, cover, density, biomass, grasslands, invertebrates, plant/animal interactions, succession, plants |
| Geographic Location: | Bounded by (40.857500N,-104.785833W) and (40.800278S,-104.730556E). Altitude Range: 1645.0 to 1675.1 Meters above sea level |
| Related Datasets: |
SGS-LTER Ecosystem Stress Area - long-term density dataset following nutrient enrichment stress on the Central Plains Experimental Range in Nunn, Colorado, USA 1975-present |
| Related Publications: |
Coffin, D. P., W. A. Laycock, and W. K. Lauenroth. 1998. Disturbance intensity and above- and belowground herbivory effects on long-term (14y) recovery of a semiarid grassland. Plant Ecology. 139: 221233 |
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