Restoration projects based on meeting ecological objectives should consider natural variability, different land use histories, and recent mortality events, and avoid applying a uniform approach. Effective restoration strategies (both passive and active) are more likely when based on identification of specific restoration needs (e.g., age structure alteration, invasive species control) for a given landscape, and when validated by scientific evidence that: a) elucidates key differences between historical and contemporary conditions; and b) identifies underlying causes of those differences. Restoration efficacy may be further enhanced when potential future interactions among land use, invasive species, and climate are considered. In this presentation, I discuss these topics in light of biomass harvest potential in piñon-juniper ecosystems, with a focus on the Colorado Plateau and the Four-Corners region.

The historical context of pinyon-juniper woodland dynamics in the Great Basin is reviewed with particular emphasis on implications for biomass utilization. Separation of “persistent” from “expansion” woodlands provides an initial landscape classification for informing restoration planning. Much of the current woodland area can be considered persistent, in that: (a) mixed-age woodland (including old trees) currently occupies areas of low fire risk where trees have long been present; (b) woodland in an early- to mid-successional stage occupies area that burned within past decades; or (c) woodland in an early- to mid-successional stage occupies area that was deforested during the late 19th Century. The second and third types are often erroneously considered expansion woodland. Guidelines are provided for field identification of the three types of persistent woodland. Biomass use for ecological restoration of persistent woodlands could include thinning or fuelbreak construction for reduction of fire spread and risk of subsequent conversion to non-native species dominance.

Expansion woodland, defined as locations where trees have recently invaded plant community types that had been in a nonforested state for multiple centuries, can be of at least two types: (a) tree invasion into adjacent plant communities as a result of over-grazing and/or fire exclusion; and (b) range expansion of pinyon and juniper species in response to climate change of recent decades. The first case seems a reasonable target for ecological restoration in the form of conversion from woodland to other vegetation types, whereas removal of trees in the second case would counter the direction of managing for adaptation to future climate change. The state of current research is reviewed for distinguishing these two cases.

With clear targets set at appropriate spatial and temporal scales, biomass use of pinyon-juniper woodlands can possibly help to satisfy multiple landscape restoration objectives. These might include diverse goals that go beyond reduction of fire risk and invasive plant dominance, including the maintenance of a diverse habitat mosaic comprised of various successional stages, fostering of landscapes resilient to disturbance and climate change, and supporting local economies. Doing so effectively requires careful consideration of the ecological context for what has caused changes in tree population processes and distribution in the past, and for understanding the likely trend of such changes in the future. This ecological context varies across the landscape with land-use history and site environment. Yet without an effort to grapple with this complexity, we risk repeating the mistakes of the past: rampant deforestation, environmental degradation leading to weed infestation, and widespread chainings that met neither the goals of long-term tree removal nor establishment of resilient plant communities. To maintain public trust, ecological restoration should incorporate pinyon-juniper woodlands as a valued landscape component to be managed sustainably at the level of landscape planning, providing essential context for site-specific projects aimed at tree removal.