Theodore A. Sickley

Assessing potential gray wolf restoration in the northeastern United States : A spatial prediction of favorable habitat and potential population levels

The northeastern United States was previously identified under the U.S. Endangered Species Act (ESA) as a potential location for restoration of a population of the endangered eastern timber wolf or gray wolf (Canis lupus). The gray wolf has been protected under the ESA since 1974. We used Geographic Information Systems (GIS) and a logistic regression model based on regional road abundance to estimate that the Northeastern states from Upstate New York to Maine contain >77,000 km 2 of habitat suitable for wolves. Using current habitat distribution and available ungulate prey (deer and moose), we estimate the area is capable of sustaining a population of approximately 1,312 wolves (90% CI = 816-1,809). This estimate is equivalent to new, much higher potentials estimated for northern Wisconsin and Upper Michigan, where wolves are rapidly recovering in the U.S. Midwest. Potential wolf densities vary from a low of 53,500 km 2 ) is capable of supporting approximately 1,070 wolves (90% CI = 702-1,439). Such large areas are increasingly rare and important for wolf recovery if populations large enough to have long-term evolutionary viability are to be maintained within the United States. However, large-scale restoration of a top carnivore like the wolf has other consequences for overall forest biodiversity in eastern forests because wolf recovery is dependent on high levels of ungulate prey, which in turn have other negative effects on the ecosystem. In the United States, planning for wolf restoration in the Northeast should take advantage of experience elsewhere, especially the upper Midwest.

Causes and Implications of Species Restoration in Altered Ecosystems

gered Species Act of 1973 one year after passage. Since that time, natural recolonization and population recovery of wolves in the western Great Lakes region of the United States (the Lake States-Minnesota, Wisconsin, and Michigan) has been a notable success of the Act (Refsnider 1994). At the time of listing, the wolf was extirpated throughout the United States outside Alaska except for remnant populations in northeast Minnesota and on Isle Royale, in Lake Superior (Mech 1970). Since protection under the Act, the wolf population has in-

Simulating the Effects of Fire Reintroduction Versus Continued Fire Absence on Forest Composition and Landscape Structure in the Boundary Waters Canoe Area, Northern Minnesota, USA

The Boundary Waters Canoe Area (BWCA) Wilderness of northern Minnesota, USA, ememplifies how fire management and natural disturbance determine forest composition and landscape structure at a broad scale. Historically, the BWCA (>400,000 ha) was subject to crown fires with a mean rotation period of 50–100 y. Fires often overlapped, creating a mosaic of differently aged stands with many stands burning frequently or, alternatively, escaping fire for several centuries. The BWCA may never have reached a steady-state (defined as a stable landscape age-class structure). In the early 1900s, a diminished fire regime began creating a more demographically diverse forest, characterized by increasingly uneven-aged stands. Shade-tolerant species typical of the region began replacing the shade-intolerant species that composed the fire-generated even-aged stands. Red pine (Pinus resinosa) stands are relatively uncommon in the BWCA today and are of special concern. The replacement of early-to-midsuccessional species is occurring at the scale of individual gaps, producing mixed-species multiaged forests. We used LANDIS, a spatially explicit forest landscape model, to investigate the long-term consequences of fire reintroduction or continuing fire absence on forest composition and landscape structure. Fire reintroduction was evaluated at three potential mean fire rotation periods (FRP): 50,100, and 300 y. Our model scenarios predict that if fire reintroduction mimics the natural fire regime (bracketed by FRP = 50 and 100 y), it will be most successful at preserving the original species composition and landscape structure, although jack pine (Pinus banksiana) may require special management. With limited fire reintroduction, all of the extant species are retained although species dominance and landscape structure will be substantially altered. If fire remains absent, many fire-dependent species will be lost as local dominants, including red pine. The landscape appears to be in a state of rapid change and a shift in management to promote fire may need to be implemented soon to prevent further deviation from historic, presettlement conditions.

Spatial Controls of Pre–Euro-American Wind and Fire Disturbance in Northern Wisconsin (USA) Forest Landscapes

We elucidate spatial controls of wind and fire disturbance across northern Wisconsin (USA), where climatic and topographic gradients are not strong, using data from the original US Public Land Survey (PLS) notes. These records contain information on the location and extent of heavy windthrows and stand-replacing fires prior to Euro-American settlement. The spatial patterns of windthrow and fire were spatially clustered at all scales in this historical environment, with stronger associations at local than regional scales. Logistic regression shows environmental variables to have a strong influence on this pattern. In the case of heavy windthrow, environmental drivers of disturbance pattern are fairly consistent across the region. The effects of climate and vegetation are predominant at all scales, but effects are often indirect, with strong interactions between them. Interactions between these two drivers and soil characteristics are also sometimes present. In contrast, models of stand-replacing fire show simple and direct control within and across fire-prone landscapes of historical northern Wisconsin, with climate and physiography as the main factors explaining the distribution of fire disturbance. This simple and direct control is lost at the regional scale, where climate, physiographic, soil, and vegetation variables, along with interactions between them, are significant factors. Contrary to other regions, the topographic effects are generally not important in predicting either wind or fire disturbance. Our work suggests that, in landscapes that lack strong environmental patterning, climate maintains its role as a primary driver of these natural disturbances, but topography is replaced by interactions and feedbacks with other forms of environmental heterogeneity.

Change in Occupied Wolf Habitat in the Northern Great Lakes Region

The concept of w olf habitat and relative suitability has changed significantly over the past several decades. In large part, this occurred because of insights gained during expansion of the wolf population in the northern Great Lakes states (Mech 1970 ; Erb and DonCarlos, this volume; Beyer et al., this volume; Wydeven et al., this volume). Protection from intentional killing of wolves since 1974, under the Endangered Species Act of 1973, began the process of wolf population growth and expansion in northeastern Minnesota, with eventual recolonization of northern Wisconsin and upper Michigan (Beyer et al., this volume; Wydeven et al., this volume). In 1955, W isconsin game manager John Keener wrote about wolves, “This animal is a symbol of the true wilderness. He cannot tolerate the advancing civilization of his wild home” (Keener 1955 : 22). As late as the 1980s it was still generally believed that wolves required wilderness to survive, though research was beginning to show otherwise (Mech et al. 1988 ; Mech 1989) . This concept lasted for so long in part because wolves had persisted only in the Boundary Waters Canoe Area Wilderness and adjacent areas of the Superior National Forest in northeastern Minnesota (Erb and DonCarlos, this volume), as well as Isle Royale National Park in Lake Superior (Vucetich and Peterson, this volume). Gradually, it became clearer that the role of wilderness was largely one of protection for wolves from killing through reduced human accessibility, rather than any innate requirements of wolves and their behavior (Mech 1995) . With protection, wolves colonized areas with greater human presence. At the same time, remoteness clearly has a positive effect on wolf survival because of reduced conflict with humans, reduced accidental killing of wolves (such as by vehicles), and perhaps less disease, as well as less intentional illegal killing. Remoteness provides one relative factor in defining degrees of habitat suitability for wolves. The other important factor is prey abundance. Ironically, in today’s human-dominated landscape, these factors are often in conflict. Human-dominated landscapes, both forests subject to harvesting and re-growth and agricultural lands, support high levels of prey (white-tailed deer,

L. D. Mech Critique of Our Work Lacks Scientific Validity

Abstract An accompanying article in this issue of the Bulletin (Mech 2006) purports to critique our past research. L. D. Mech attempts to show that our model of prospective, preferred gray wolf (Canis lupus) habitat (Mladenoff et al. 1995, 1997, 1999, Mladenoff and Sickley 1998) has been incorrect. We first state clearly that we are not opposed to the re-assessment of our work based on new data. However we believe the Mech paper contains both serious conceptual and methodological flaws that render its conclusions invalid. Our own analysis, based on logic and current techniques (Mladenoff et al. 2005), shows that the model has behaved according to our predictions and continues to successfully predict wolf recolonization in Wisconsin, USA, over more than 25 years. However, the serious flaws of Mech (2006) alone show that he is incorrect in his putative critique of our work.