Basing Elk Population Limits on Direct Measurements of Vegetation Health and Use Patterns. By: Catherine Schnurrenberger, C.S. Ecological Surveys and Assessments, 11331 Star Pine Rd. Truckee, CA 96161. cadavis@ltol.com
Why do we need effective monitoring of elk impacts? Elk numbers are increasing in Nevada Elk are expanding their range There is concern over competition with livestock and other wildlife species It is easier to manage elk numbers before there are significant detrimental impacts
Elk in Nevada Past and Present McCullough, 1969 Historical Elk Distribution Current Elk Distribution Nevada
Set Clear Goals!!! No reduction in livestock AUMs Healthy Aspen stands No impact on Mule Deer Healthy Riparian areas No direct competition with livestock Protection of special-status species
What have we learned from past monitoring? 1. Need to verify elk use by, pellet counts, fecal analysis, sitings (NDOW, hunters, ranchers). 2. Need to sample plant communities of interest/concern. 3. Elk impact some vegetation types at lower population densities i.e. Aspen stands. 4. Need to incorporate impacts from livestock, wildlife, pathogens and wildfire 5. Need to account for herd movement and variability year to year. 6. Quantitative data is best, most defensible, easiest to compare year to year, but all observations are useful.
How have we monitored to achieve goals? Goal 1. No reduction in AUMs, no direct competition with livestock 2. Healthy Aspen stands 3. Healthy riparian areas 4. No competition with Mule deer Monitoring method 1. Pellet counts, utilization and cover by desired species. 2. Stand structure data, pellet counts, utilization and microhistal analysis. 3. Pellet counts, use on willows and key species. 4. Pellet counts, utilization of key species and microhistal analysis.
Goose Creek Elk Management Area, BLM. 2006 Dinner Springs and Winecup Ranch wet meadow/riparian areas. Dinner Springs (SM17) use by cattle, >90%. No signs of elk use here. WT-04 Private riparian land not grazed by cattle for 5 years, detected 10-15% elk use on key graminoids.
Goose Creek 2006 Sites on left grazed by cattle, sites on right wildlife only. Average Use of Graminoids at Riparian Sites, 2006 Percentage of Key Graminoids Utilized 100 90 80 70 60 50 40 30 20 10 0 83.90 90.00 SM-05 FALL 06 SM-17 FALL 06 SM-06 ( Rip) FALL 06* 0.00 13.50 WT-04 SUMMER 06* Site and Season Monitored
Bruneau River 2003 Deep Creek Riparian little elk use. Sand Creek little use on graminoids and regeneration of willows.
Bruneau River Mesic/Moist Meadow Sites, 2003 Tennesse Creek Mud Springs
Bruneau River Mesic/Moist Meadow Sites, 2003 Taylor Creek Rowland
Graph of Cover at Bruneau River Mesic Sites, 2003 100 90 80 70 60 50 40 30 20 10 0 Percent Foliar Cover from Grasses and Forbs at Mesic or Moist Meadow Sites Cattle No Cattle Cattle Cattle No Cattle Bristol Springs Mud Springs Rowland Taylor Creek Tennessee Creek
Bruneau River Elk Monitoring Deep Creek early spring trailing by elk 2009 Highest use on white wyethia
Jarbidge 2010 Lower Williams Basin willow hedging Lower Williams Basin willow damage, little use on graminoids
Jarbidge 2010 Caudle Creek willow browse by elk Cherry Creek willow browse by livestock
Elk Numbers in Different Areas Area Year Elk numbers Area sq. miles Elk density Bruneau River USFS 2003 650 250 2.6 Bruneau River USFS 2009 1,100 250 4.4 Bruneau River USFS Now 4,000 250 16.0 Jarbidge USFS 2010 1,000 270 3.7 Jarbidge USFS Now 2,500 270 9.3 Goose Creek BLM 2006 1,100 957 1.1 Goose Creek BLM Now 1,900 957 2.0
Upland Sagebrush/grassland This vegetation type is important to livestock and wildlife. This vegetation type is the most abundant throughout Nevada AUMs may be based in part on the amount of key species: bluebunch wheatgrass, Idahoe fescue Allowable use and on/off dates often based on utilization of these key species
Monitoring production and utilization of key bunchgrasses, Goose Creek BLM 2006
Percent Utilization on Bluebunch Wheatgrass, Goose Creek BLM 2006 60 50 40 30 20 10 0 Cattle Cattle Cattle Cattle Cattle Cattle Cattle Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle No Cattle
100 90 80 70 60 50 40 30 20 10 0 Winter Use by Elk at Upland Sites, Bruneau River 2009 Residual Current
There are standardized sampling techniques and guidelines for Aspen Stands Sampling should include: 1) Number of stems/acre by age class 2) Account of stand health including parasites and pathogens 3) Canopy cover by aspen and conifers 4) Quantitative measure of browse by insects and ungulates 5) Measure of rubbing/biting by elk especially on pole size aspen 6) GPS location data 7) Some assessment of the understory plant community Aspen as a Special Concern Aspen stands are declining throughout the west. Age class or stand structure data shows a lack of aspens in the 25 50 year age class (pole/sapling or regenerative age class). Impact on this age class is related to past grazing by livestock. Elk browse is detectable on suckers and saplings and contributes to mortality of these age classes.
Aspen Jarbidge, Caudle Creek.
Jarbidge Cherry Cr. little regeneration Goose Creek aspen stand little regeneration
Jarbidge Deer Creek. Elk wallow and browse. Jarbidge Lower Williams Basin. Current use by elk only no livestock.
Need to verify use by ungulate species Browse of Young Aspen Related to Density of Ungulate Pellets Current and Old Ungulate Pellets/Acre 3000 2500 2000 1500 1000 500 0 Bucks Creek Aspen Ungulate Pellets/acre Elk & Deer Pellets/Acre Browse of Young Aspen Copper Basin Aspen #1 Copper Basin Aspen WP 586 old #2 Deep Creek Aspen Sept Mc Donald Aspen new Pine Mnt Aspen Rattlesnake Aspen Rocky Gulch Aspen Tennessee Aspen 100 90 80 70 60 50 40 30 20 10 0 Percentage of Young Aspen Browsed
Number of Pole versus Sucker Age Class Aspens Related to Current Browse on Suckers, Jarbidge 2010 Ratio of Aspen Poles to Aspen Suckers 1.20 1.00 0.80 0.60 0.40 Ratio Pole/Sucker age class % Current Browse 100% 90% 80% 70% 60% 50% 40% 30% Percentage of Browsed Suckers 0.20 20% 10% 0.00 Caudle Cr Aspen Cherry Cr Aspen Deer Cr Aspen Draw Cr Ridge Aspen Humm. Sprgs Aspen Lime Cr Lower Upper Raker Basin Aspen Williams Cr Aspen Basin Aspen Short Cr Aspen Up Draw Cr Aspen Upper T Cr Aspen Upper Williams Basin Aspen 0%
Illustration: Sequenced Stem Production Current year s growth = cyg Dormant bud = db Lateral bud = lb Previous year s growth = pyg Terminal bud = tb Terminal bud scar = tbs Schematic of willow stems showing annual height growth without browsing (a), with browsing (b), and with an alternating pattern of browsing and nonbrowsing (c). Adapted from Keigley and Frisina (1998). In INCREASED WILLOW HEIGHTS ALONG NORTHERN YELLOWSTONE S BLACKTAIL DEER CREEK FOLLOWING WOLF REINTRODUCTION, Beschta and Ripple, 2007. Arrested, Retrogressive, or Released Growth Type Uninterrupted Growth Type Reproduced courtesy of Keigley and Frisina (1998), in Browsed Plant Method for Young Quaking Aspen, USDA, 2004.
Often a stand with no or few pole or regeneration age aspen and high ungulate browse will have a very high number of sucker or reproduction age aspen.
Microhistal Analysis of Current Year Elk Pellets, Bruneau River Area Grass Forbs Shrubs Aspen 100% 90% Composition by Graminoid, Forb, Shrub and Aspeni 80% 70% 60% 50% 40% 30% 20% 10% 0% Aspen Bucks Cr. Aspen Copper Basin Aspen McDonald Aspen Rattlesnake Aspen WP 583 MM and MS Rattlesnake
Mountain Mahogany
Mature MM highlined, no longer produces lower branches. Severe browse on juvenile MM, this is most likely 30 years old.
Mountain Mahogany by Age Class, Bruneau 2009. Average Stem Density of Mountain Mahogany, by Age Class, 2009 250 Juvenile Immature/ Young Mature Mature Decadent 200 Average Stems/Acre 150 100 50 0 Bridge Gulch MM Merritt Mnt MM Rattlesnake MM Sand Creek MM Telephone Creek MM
Mountain Mahogany Stems per Acre by Age Class Seedling/Juvenile Immature Young Mature Mature Decadent 900 800 700 Number of Stems/Acre 600 500 400 300 200 100 0 Buckhorn Ridge MM Goat Cr MM MM#1 MM#2 N. Cottonwood MM Raker MM T Cr MM Upper Draw Cr MM
Jarbidge 2010, Browse on MM is higher at sites with less understory. Total Understory Plant Cover Related to Use on Mountain Mahogany Average Percentage of Mountain Mahogany Leader Use 60 50 40 30 20 10 0 R² = 0.3827 0 10 20 30 40 50 60 70 80 90 100 Percentage Understory Cover
Closed canopy mature mnt. mahogany stand at T Cr. with no regeneration (left) and an open mnt. mahogany stand with regeneration (right). Jarbidge 2010.
Need to incorporate other impacts, livestock grazing, fire, roads etc. East Ridge Fire burned 54,500 acres of USFS land in 2008. In 2007 the Murphy Fire Complex burned 595,699 acres, 436,402 acres of BLM land in Idaho and Nevada, and 91,185 acres of Forest Service in Nevada.
Effect of fire on aspen stands Average Density of Aspen per Acre, by Age Class Sprout Sucker/Seedling Pole/Sapling Mature Decadent 15000 14000 13000 4114 12000 11000 10000 236 0 Average Stems/Acre 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 Bucks Creek Aspen 4688 764 495 899 270 315 225 225 180 2113 1574 4721 5621 1124 5969 101 225 337 0 135 585 0 585 719 2428 315 719 1248 315 674 360 944 674 360 472 225 540 0 270 315 Copper Basin WP 586 Copper Basin #3 Copper Basin #1 Pine Mnt. Rattlesnake Tennesse Mnt. Deep Creek Rocky Gulch
Effects of Fire on Sagebrush, Bruneau River 2009. Number of Live and Dead Stems/ Acre Burned Sagebush-bunchgrass Sites, Bruneau River 2009 Dead Live 6000 5000 4000 3000 2000 1000 0 Hot Sprg Butte US Rocky Gulch US #1 Rocky Gulch US #2 Taylor Pocket US Wickiup US Stems/acre
Take home message from vegetation monitoring in other areas of Nevada Elk are not competing with livestock in wet meadows and riparian areas. Elk use on upland grasses is so dispersed it is often difficult to measure. Elk have affected aspen regeneration, however stand structure data indicates past livestock use impaired regeneration prior to the presence of elk. Mountain mahogany sites are preferred elk habitat and there may be impacts from elk.
We all care about this land, we all care for this land. May we manage it for future generations.