The sage-grouse habitat mortgage: effective conifer management in space and time

Authors: Boyd, Chad; KERBY, JAY - Nature Conservancy; SVEJCAR, TONY - Oregon State University; Bates, Jonathan - Jon; JOHNSON, DUSTIN - Oregon State University; Davies, Kirk

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2016
Publication Date: 1/15/2017
Citation: Boyd, C.S., Kerby, J., Svejcar, T., Bates, J.D., Johnson, D., Davies, K.W. 2017. The sage-grouse habitat mortgage: effective conifer management in space and time. Rangeland Ecology and Management. 70(1):141-148. doi:10.1016/j.rama.2016.08.012.

Interpretive Summary: The presence of even small amounts of conifers > 1 m in height within sage-grouse habitat dramatically reduces habitat quality for this species and necessitates conifer control to maintain habitat value. We estimated the amount of conservation effort needed to control conifers by developing a novel metric (“conservation volume”) that integrates the spatial area of conifer control with the desired temporal management horizon and used this approach as a base layer to compare cutting vs fire-based conifer control techniques in sage-grouse habitat. Efforts to control conifers using cutting may have short treatment lifetime and are relatively expensive compared to fire-based control, which is comparatively inexpensive, may have longer treatment lifetime, but has the disadvantage temporarily reducing or eliminating sagebrush, and consequently, sage-grouse habitat. We concluded that utilizing a combination of fire and cutting treatments is most financially and ecologically sustainable over the long time horizons (100 years) involved in managing conifer-prone sage-grouse habitat.

Technical Abstract: Management of conservation-reliant species can be complicated by the need to manage ecosystem processes that operate at extended temporal horizons. One such process is the role of fire in regulating abundance of expanding conifers that disrupt sage-grouse habitat in the northern Great Basin of the US. Removing conifers by cutting has a beneficial effect on sage-grouse habitat. However, effects may last only a few decades because conifer seedlings are not controlled and the seed bank is fully stocked. Fire treatment may be preferred because conifer control lasts longer than for mechanical treatments. The amount of conservation needed to control conifers at large temporal and spatial scales can be quantified by multiplying land area by the time needed for conifer abundance to progress to critical thresholds (i.e. “conservation volume”). The contribution of different treatments in arresting conifer succession can be calculated by dividing conservation volume by the duration of treatment effect. We estimate that fire has approximately twice the treatment life of cutting at time horizons approaching 100 years, but, has high up-front conservation costs due to temporary loss of sagebrush. Cutting has less up-front conservation costs because sagebrush is unaffected, but is more expensive over longer management time horizons because of decreased durability. Managing conifers within sage-grouse habitat is difficult because of the necessity of not only maintaining the majority of the landscape in sagebrush habitat, but the threshold for negative conifer effects occurs fairly early in the successional process. The time needed for recovery of sagebrush creates limits to fire use in managing sage-grouse habitat. Utilizing a combination of fire and cutting treatments is most financially and ecologically sustainable over long time horizons involved in managing conifer-prone sage-grouse habitat.