Controlling Invasive Grasses to Reduce Wildfire Risk in Arid Lands

Invasive perennial and annual grasses (e.g., buffelgrass, fountain grass, cheatgrass) change desert fuel structure by creating continuous, fine fuels that carry fire across landscapes historically resistant to large, intense wildfires. Effective control requires an integrated program of monitoring, rapid response, removal, fuel breaks, and long-term restoration to re-establish native vegetation patterns.

1. Monitor and map invasions early

Survey priority areas annually: roadsides, wash corridors, disturbed sites, and near urban edges. Use a simple presence/cover rating (none, trace, patch, dominant) by 100 m transects. Where resources allow, augment field work with high-resolution satellite or drone imagery to map large, continuous infestations and track spread over time.

2. Prioritize treatment units

Rank patches for action using four criteria: proximity to infrastructure or valued resources (towns, springs, reserves), infestation size and connectivity (small isolated patches first when eradication is feasible), invasion stage (young seedlings easier to remove), and available capacity and funding. Treat high-risk corridors that would increase landscape fuel continuity if left unchecked.

3. Mechanical and manual removal

For small patches and seedlings, hand-pulling before seed set is highly effective. For larger tussocks or clonal stands, use targeted mowing or brush-cutting timed to remove biomass before seeding. Remove cut material from the site or chip it to prevent creating added fuel beds. Avoid heavy soil disturbance that promotes reinvasion.

4. Targeted chemical control

Apply selective herbicides (e.g., glyphosate or grass-selective products where permitted) in spot treatments during active growth but before flowering. Use basal-stem or cut-stem applications where feasible to reduce non-target impacts. Always follow label directions, local regulations, and minimize spray drift into native vegetation.

5. Prescribed fire and wet-season mowing as tools (with caution)

Prescribed burns or strategic mowing can reduce fuel loads where safe and legal, but in many arid systems these actions risk damaging biological soil crusts and native seedlings. Use them only as part of a documented fuels-management plan and combine with post-treatment restoration to prevent reinvasion.

6. Create and maintain strategic fuel breaks

Establish fuel breaks by restoring native patchiness—widen existing barren strips, remove invasive grasses along key containment lines, and maintain them through annual monitoring. Fuel breaks should be placed to protect high-value assets and to compartmentalize the landscape so wildfires cannot spread uninterrupted through invasive grass fuels.

7. Restore native plant communities

After invasive removal, stabilize soils and outcompete seedlings by re-establishing native grasses, shrubs, or forbs adapted to local microsites. Use local-genotype seed mixes, time seeding to favorable wet seasons, and apply mulch or soil amendments only when they aid establishment without promoting invasives.

8. Grazing and land-use adjustments

Manage livestock intensity and timing to avoid creating bare ground that favors invasive grass establishment. Where practical, rotate grazing or defer during vulnerable seasons and fence critical restoration zones until native cover is re-established.

9. Community engagement and rapid-response networks

Train landowners, managers, and volunteers to recognize target invasive grasses and report sightings. Establish rapid-response teams with mapped priorities, treatment kits, and seed sources so emergent patches are removed before they produce seed.

10. Monitor outcomes and adapt

Track treatment effectiveness with simple metrics: change in percent cover, patch size, and seedbank presence. Re-treat surviving plants and adjust methods as needed. Long-term monitoring helps identify whether additional tactics (biological control trials, altered disturbance regimes) are warranted.

Combining early detection, prioritized rapid response, careful removal, fuel-break placement, and native restoration breaks the invasive grass–fire feedback loop and lowers wildfire risk in arid lands. Local regulations, available budgets, and ecological context should guide specific methods and timing.

Sources

• Monitoring and Removal of Invasive Grasses for Restoration of Dry Desert Systems (Southwest Fire Science Consortium; 2023-07-24)