RESEARCH BRIEF: Cost- benefit analysis of vegetation removal + seeding

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Weighing costs relative to outcomes: woody and invasive plant removal followed by seeding in shrublands and woodlands.

New study by RAMPS researchers examines how the costs of vegetation treatments related to outcomes. 

Background:

The increase of undesirable woody and invasive plants on public and private lands elevates wildfire risk, alters habitat, and can lead to erosion. Expensive vegetation treatments are widely implemented each year and include removal of undesirable species and subsequent seeding. Despite these investments to improve ecosystem health, treatments are rarely evaluated to determine whether more spending improves intended outcomes. We assessed commonly employed vegetation treatments and costs relative to their outcomes across sagebrush shrublands and pinyon-juniper woodlands in the western USA. Our results give managers information on how money spent on various treatment combination relates to desired outcomes, and highlights the areas where more spending can yield better results. Given the growing need and costs of land management actions, we raise the importance of specifying treatment budgets and objectives and coupling this with effectiveness monitoring, to improve future efforts.

Study Sites:

74 sites in Utah’s Watershed Restoration Initiative across big sagebrush and pinyon-juniper plant communities treated between 2004 and 2018.

Treatment combinations of vegetation removal (top) and seeding (bottom).

The study examined four types of treatments typically performmed in the study area. These treatment combinations were chosen for the study because there was enough data across the study area to yield scientifically robust results.

Treatment combinations tested in the study: Herbicide + drill seeding, Harrowing + broadcast seeding, Chaining + Aerial seeding

TREATMENT COMBINATIONS VEGETATION RESPONSES FACTORS ANALYZED
Herbicide + Drill seeding Cover of woody species and cheatgrass Treatment type
Harrowing + Broadcast Seeding Cover of seeded perennial grasses and forbs Costs of vegetation removal, seeding and seed mix
Chaining + Aerial Seeding   Time since treatment
Mastication + Aerial Seeding    

 

Summary of results

The following results are summarized in the table below.

If the desired outcome from a manager was to decrease woody plant cover, then spending more on either mastication + aerial seeding or harrowing + broadcast seeding yeilded better results. However, the mastictaion + aerial seeding treatment costed more than any other treatment for the best outcome. A double-pass with the harrow reduced woody plant cover for a longer period of time.

If the desired outcome was to decrease cheatgrass cover, then the herbicide + drill seeding treatment yielded the best results. The higher cost of applying a second application of herbicide was even better at reducing cheatgrass cover.

If the desired outcome was to increase perennial grass cover, then the herbicide + drill treatment or the harrowing + broadcast seeding treatments worked best. Also, spending money on removal treatments was better than spending this money on seed mixes and seeding treatments for this desired outcome.

If a manager's goal was to increase perennial forb cover and species richness, then the chaining + aerial seeding treatment was the best way to accomplish that goal. In addition, increased costs for this treatment was related to adding more species to the seed mix. The study found that the herbicide + drill treatment was a poor choice for this goal, as it reduced forb cover and species richness.

Figure showing results from the study.

Other Results: 

  • All mechanical vegetation removal treatments increased cover of invasive cheatgrass.
  • Regrowth of woody plants happened at the same rate, regardless of the treatment used.
  • Forb cover increased if seeding was followed by a wet winter.

*  cost-effective treatment means that spending more improved desired outcome.

Assessments of the costs and outcomes of treatments allow for more cost-effective planning, improve outcomes, and offer the opportunity to allocate resources for maximum benefit – also known as getting the “biggest bang for the buck”.

 

Read the Paper

“The biggest bang for the buck: cost-effective vegetation treatment outcomes across drylands of the western USA” by Seth Munson, Ethan Yackulic, Lucas Bair, Stella Copeland and Kevin Gunnell published in Ecological Applications, http://doi.org/10.1002/eap.2151

An infographic summarizing activities of the RAMPS program.

 

 

This study is a part of the USGS Southwest Biological Science Center’s Restoration Assessment & Monitoring Program for the Southwest (RAMPS). RAMPS is an inter-disciplinary network of scientists, land managers & practitioners that strengthens restoration strategies & outcomes across the southwestern US.

WEBSITE: https://usgs.gov/sbsc/ramps

This project was a collaborative effort between USGS and the Utah Department of Natural Resources