Jonathan W. Long

Science synthesis to support socioecological resilience in the Sierra Nevada and southern Cascade Range.

A team of scientists integrated recent research to inform forest managers, stakeholders, and interested parties concerned with promoting socioecological resilience in the Sierra Nevada, southern Cascade Range, and Modoc Plateau. Among the focal topics were forest and fire ecology; soils; aquatic ecosystems; forest carnivores including Pacific fisher, marten, and California spotted owl; air quality; and the social, economic, and cultural components of socioecological systems. The synthesis adopted a holistic perspective by focusing on issues that cross scientific disciplines and considering the integrated nature of terrestrial and aquatic systems and the interconnections between restoration of ecological processes and the social and economic concerns of communities. A central theme is the importance of restoring key ecological processes to mitigate impacts of widespread stressors to socioecological resilience, including changes in climate, fire deficit and fuel accumulations, air pollution, and pathogens and invasive species. Key findings from the synthesis were that (1) efforts to promote resilience of socioecological systems increasingly consider the interaction of social values and ecological processes in pursuit of long-term mutual benefits and social learning for local communities and larger social networks; (2) strategic placement of treatments to reduce hazardous fuel accumulations and to restore fire as an ecosystem process within large landscapes can lower the risk of uncharacteristically large, severe, and dangerous fires, and their associated impacts to sensitive wildlife species; and (3) science suggests a need for active treatment in some riparian and core wildlife habitat to restore fire and its ecological benefits. Forest landscape management will need to be adaptive as the impacts of stressors and treatments on a range of socioecological values are determined by further research and monitoring.

Consequences of Ignoring Geologic Variation in Evaluating Grazing Impacts

Abstract The geologic diversity of landforms in the Southwest complicates efforts to evaluate impacts of land uses such as livestock grazing. We examined a research study that evaluated relationships between trout biomass and stream habitat in the White Mountains of east-central Arizona. That study interpreted results of stepwise regressions and a nonparametric test of “grazed and ungrazed meadow reaches” as evidence that livestock grazing was the most important factor to consider in the recovery of the Apache trout (Oncorhynchus apache Miller). That study had assumed that geologic variation was insignificant in the study area. However, lithologic and topographic differences between the felsic slopes of Mount Baldy and adjacent mafic plateaus influence many attributes of trout habitat. We tested the robustness of the earlier study by using its dataset and its method of stepwise regression, but with the addition of a variable representing geologic variation. The results suggested that geology was a highly significant predictor of trout biomass (P < 0.0001), whereas bank damage by ungulates was not a useful predictor of residual variation in trout biomass after accounting for geology (r2 = 0.015, P = 0.290). However, the associations between natural variation and land use impacts in this spatial dataset confound attempts to make inferences concerning effects of livestock grazing upon trout. Despite fundamental problems in the analysis, the results of the earlier study were repeatedly cited in scientific literature and debates about grazing management. To fairly decipher relationships between ecological production and livestock grazing in diverse landscapes requires temporal studies with reliable methodologies and proper controls for landscape variation. Ignoring geologic variation has the potential to mislead conservation policies by inappropriately implicating land use, by undervaluing inherently favorable habitats, and by inflating expectations for inherently less favorable habitats.

Geologic influences on Apache trout habitat in the White Mountains of Arizona

Abstract Geologic variation has important influences on habitat quality for species of concern, but it can be difficult to evaluate due to subtle variations, complex terminology, and inadequate maps. To better understand habitat of the Apache trout (Onchorhynchus apache or O. gilae apache Miller), a threatened endemic species of the White Mountains of east-central Arizona, we reviewed existing geologic research to prepare composite geologic maps of the region at intermediate and fine scales. We projected these maps onto digital elevation models to visualize combinations of lithology and topography, or lithotopo types, in three-dimensions. Then we examined habitat studies of the Apache trout to evaluate how intermediate-scale geologic variation could influence habitat quality for the species. Analysis of data from six stream gages in the White Mountains indicates that base flows are sustained better in streams draining Mount Baldy. Felsic parent material and extensive epiclastic deposits account for greater abundance of gravels and boulders in Mount Baldy streams relative to those on adjacent mafic plateaus. Other important factors that are likely to differ between these lithotopo types include temperature, large woody debris, and water chemistry. Habitat analyses and conservation plans that do not account for geologic variation could mislead conservation efforts for the Apache trout by failing to recognize inherent differences in habitat quality and potential.

Understanding ecological contexts for active reforestation following wildfires

To forestall loss of ecological values associated with forests, land managers need to consider where and when to prioritize active reforestation following major disturbance events. To aid this decision-making process, we summarize recent research findings pertaining to the Sierra Nevada region of California, USA to identify contexts in which active reforestation or passive recovery may best promote desirable post-fire ecological trajectories. Based on our synthesis, we suggest conceptual frameworks for assessing landscape conditions and determining areas that may be the highest priorities for tree planting to avoid persistent loss of conifer forests. Field studies have shown that some large patches of high severity burn can have relatively low levels of natural regeneration, especially among desired pine species. The accumulation of fuels and competition with shrubs and resprouting hardwoods may hinder the reestablishment of mature conifer trees. However, severe fires could also play a restorative role, by promoting non-conifer forested communities, such as meadows, shrubfields, and open forests with significant hardwood components. Such communities were historically rejuvenated and maintained by fire but have been replaced by conifer forest due in part to fire suppression. Reforestation in such areas may run counter to restoring ecological function and the ecosystem services that are provided by non-conifer communities. Through this framework, managers and stakeholders may better understand the contexts in which planting and passive recovery may better support ecological restoration.

Erosion and Restoration of Two Headwater Wetlands Following a Severe Wildfire

Wildfire can damage headwater wetlands, yet the value of post-fire restoration treatments in channels has been contested. Staff from the White Mountain Apache Tribe, students from the local Cibecue Community School, and researchers from the U.S. Forest Service collaboratively recorded channel responses over 13 years at two headwater wetlands lying within watersheds that were severely burned by the Rodeo-Chediski wildfire (Arizona, U.S.) in 2002. One site, Turkey Spring, was left largely untreated for 11 years following the fire, while the second site, Swamp Spring, was treated in 2005 by placing large rock riffle formations and vegetation transplants to prevent further incision and stimulate wetland development. The treatment was soon followed by cessation of channel incision and reestablishment of native wetland vegetation, while headcutting caused extensive erosion at the untreated site for eight years. Radio-carbon dating indicated that the eroding soils at Turkey Spring were over 8,000 years old. This study demonstrates that headwater wetlands in this region are vulnerable to extreme incision events following high severity wildfires, but that such impacts can be partially and gradually reversed. Targeted treatments of incising channels may be warranted to conserve wetlands, soils and associated values that have established over thousands of years.