Presentation on theme: "Management of cheatgrass fuel loading in the shrub-steppe Steven O. Link, PhD (Botany) Native Plant Landscaping and Restoration LLC 4604 E. Robin Ct. West."— Presentation transcript:
Management of cheatgrass fuel loading in the shrub-steppe Steven O. Link, PhD (Botany) Native Plant Landscaping and Restoration LLC 4604 E. Robin Ct. West Richland, WA
Acknowledgement This work was funded by the Joint Fire Science Program. The work was done in cooperation with the Mid-Columbia River National Wildlife Refuge Complex. Special thanks are given to Randy Hill for help defining the questions and for continued technical support.
Bromus tectorum cover mapping and fire risk Effect of herbicide and herbicide concentration on Elymus wawawaiensis establishment in the shrub-steppe Management of fuel loading in the shrub-steppe: Responses six, seven, and eight years after treatments Fire risk in replanted bunchgrass communities
Bromus tectorum cover mapping and fire risk
Bromus tectorum infestation at the Saddle Mountain element of the Hanford Reach National Monument
High Bromus tectorum fuel load
Low Bromus tectorum fuel load
Lack of continuous fuel limits fire
Experimental Design The fire risk experiment was in plant communities that spanned the range of B. tectorum cover. Bromus tectorum cover was grouped into five classes. Each replicate is comprised of 8 to 18 plots in the three lowest B. tectorum cover classes and 2 to 6 plots at the two highest cover classes. A replicate is a collection of plots where the risk of fire was determined as the proportion of plots that burned. Each class has four replicates. We used 176 square plots, 10 m on a side. Two hundred twenty six plots, 10 m on a side, were used to related B. tectorum cover to color band intensity.
Conclusions Bromus tectorum cover can be mapped using aerial color band reflectance photos taken in late summer. Based on the B. tectorum cover map and the relationship between B. tectorum cover and fire risk, fire risk can now be mapped.
Effect of herbicide and herbicide concentration on Elymus wawawaiensis establishment in the shrubsteppe
Field site at the Columbia National Wildlife Refuge
Bunchgrass Drill Seeding Elymus wawawaiensis (Snake River wheatgrass, Secar cultivar) was drill seeded at a rate of about 7 lb. acre -1 on Feb. 19, Drill rows were 0.3 m apart.
Roundup - 2 oz/acre
Plateau - 2 oz/acre
Plateau - 4 oz/acre
Plateau - 8 oz/acre
Management of fuel loading in the shrub-steppe: Responses six, seven, and eight years after treatments
Our objective was to determine if our strategy to reduce Bromus tectorum cover and thus fire risk is sustainable after implementation. We tested three hypotheses reporting results for 2008, 2009, and Hypothesis 1: Bunchgrasses established in 2003 will show an increasing degree of B. tectorum control over three years (2008, 2009, 2010). Hypothesis 2: Native species richness and cover in Plateau plots will not be different from controls 6, 7, and 8 years after treatment. Hypothesis 3: Alien species cover in Plateau plots will not be different from controls 6, 7, and 8 years after treatment. We monitored populations, flowering, and size of established bunchgrasses. We documented new E. wawawaiensis arising from self- seeding.
Figure 1. Eighteen years after drill seeding, E. wawawaiensis, results in near elimination of B. tectorum.
Figure 4. Alien species cover from 2004 through The slope of the linear regression over time was significantly (p = ) greater than zero.
Figure 10. The relationship between E. wawawaiensis canopy volume and the interference distance with B. tectorum.
Figure 7. Elymus wawawaiensis 8 years after seeding showing senescence (gray tillers) with remaining green tillers mostly near the edge.
Figure 8. Mean and predicted % senescent plants (± 1 sem) in the imazapic seeded plots.
Figure 9. Gray colored senescing E. wawawaiensis seeded in 1986 near the study area in 2009.
Figure 11. Relation between planted bunchgrass density and B. tectorum cover.
Fire risk in replanted bunchgrass communities
Management Implications and Conclusion We conclude that B. tectorum cover can be significantly and sustainably reduced by burning and applying Plateau herbicide at 4 or 8 oz acre -1 in the fall and then drill seeding E. wawawaiensis in the late winter. Seven years after treatment application the density of drill seeded E. wawawaiensis was 1.23 ± 0.24 plants m -2. Doubling the seeding rate may increase density enough to further reduce B. tectorum cover to be closer to the minimal value of 2.8% achieved with E. wawawaiensis density of 2.77 plants m -2.
Research Questions Examine viability of bunchgrass cultivars that arose from small initial populations leading to population bottlenecks that may reduce viability. Are locally sourced native plants more likely to sustain themselves. Examine the fire risk of more restored plant communities. What combination of species leads to significant reductions of fuel cover and increases in bare soil and soil cryptogams. Can Poa secunda provide sufficient interference to reduce Bromus tectorum cover?