Landscape Management Using Historical Fire Regimes: Blue River, Oregon

Abstract

Landscapes administered for timber production by the U.S. Forest Service in the Pacific Northwest in the 1950s-1980s were managed with dispersed patch clearcutting, and then briefly in the late 1980s with aggregated patch clear-cutting. In the late 1990s, use of historical landscape patterns and disturbance regimes as a guide for landscape management has emerged as an alternative to the static reserves and standard matrix prescriptions in the Northwest Forest Plan. Use of historical information to guide management recognizes the dynamic and variable character of the landscape and may offer an improved ability to meet ecosystem management objectives.We describe a landscape management plan based in part on interpretations of historical disturbance regimes. The plan contains a reserve system and other landscape areas where three distinct types of timber harvest are prescribed. Timber harvest prescriptions approximate the frequency, severity, and spatial extent of past fires. Future harvest blocks are mapped and used to project forest patterns 200 yr forward and to map resulting landscape structure.This plan is compared with an alternative plan for the same area based on the extensive reserves and prescriptions for matrix lands in the Northwest Forest Plan. The management approach based on historical patterns produced more late-successional habitat (71% vs. 59%), more overstory structure in young stands (overstory canopy cover of 15-50% vs. 15%), larger patches (mean patch size of 48 vs. 26 ha), and less edge between young and old forest (edge density of 19 vs. 37 m/ha). While landscape structures resulting from both plans are historically unprecedented, we feel that landscape management plans incorporating key aspects of ecosystem history and variability may pose less risk to native species and ecological processes.

Forest fuel reduction alters fire severity and long‐term carbon storage in three Pacific Northwest ecosystems

“…Fires can increase (or decrease) in severity depending on how much the weighted fuel index of a given cell exceeds (or falls short of) the fuel level thresholds for each fire severity class (T light , T medium , T high , and T max ), and the probability values for the increase or decrease in fire severity (P i and P d ). For example, while the natural fire severity of many stands of the west Cascades can be described as high severity, other stands of the west Cascades have a natural fire severity that can be best described as being of medium severity (;60-80% overstory tree mortality) (Cissel et al 1999). For these stands, medium-severity fires are scheduled to occur throughout the simulated stand and can increase to a high-severity fire depending on the extent to which the weighted fuel index in a cell exceeds the threshold for a high-severity fire, as greater differences between the fuel index and the fire severity threshold will increase the chance of a change in fire severity.…”

“…For this reason, our experiment incorporated a factorial blocking design where each ecosystem was subjected to four different frequencies of each fuel reduction treatment. We also recognize the fact that fire return intervals can exhibit substantial variation within a single watershed, particularly those with a high degree of topographic complexity (Agee 1993, Cissel et al 1999), so we examined two likely fire regimes for each ecosystem. Historic fire return intervals may become unreliable predictors of future fire intervals (Westerling et al 2006); thus ascertaining the differences in TEC l that result from two fire regimes might be a useful metric in gauging C dynamics resulting from fire regimes that may be further altered as a result of continued global climate change.…”

“…Bork (1985) estimated a mean fire return interval of 16 years for the east Cascades Pinus ponderosa forests, and we also considered a mean fire return interval of 8 years for this system. Cissel et al (1999) reported mean fire return intervals of 143 and 231 years for forests of medium-and high-severity (standreplacing) fire regimes, respectively, among the Tsuga heterophylla-Pseudotsuga menziesii forests of the west Cascades. Less is known about the fire history of the Coast Range, which consists of Tsuga heterophylla-Pseudotsuga menziesii communities in the interior and Tsuga heterophylla-Picea sitchensis communities occu- pying a narrow edge of land along the Oregon Coast.…”

Development of Tree Size Distributions in Douglas‐fir Forests Under Differing Disturbance Regimes

“…Alternatively, the chronic/partial fire model might offer alternatives to hands-off management in matrix forests. Managers might choose to silviculturally emulate the effects of partial fires through partial cuttings (e.g., thinning and underplanting or green-tree retention), or reintroducing partial fires to create snags and coarse woody debris (Cissel et al 1999) to speed up the creation of old-growth structures. Such active management would require a deliberate choice of fire intensity and the amount and pattern of residual trees, i.e., retaining enough large old overstory Pseudotsuga to garner their life-boating effects, but not too many to preclude the regeneration of shade-intolerants such as Pseudotsuga itself.…”

Novel shape indices for vector landscape pattern analysis

“…Landscape pattern analysis based on the patch-matrix model (i.e. landscape pattern indices (LPIs)) or the gradient model (McGarigal et al 2009) has, therefore, received increasing attention in both ecological research and the environmental management communities (Cissel et al 1999, Fu and Chen 2000, Turner 2005). …”