Geology topics

Constance I. Millar

Publications and source records attributed to Constance I. Millar.

7 recordsLinked to original sources

USGS2020

Climate‐change refugia: Biodiversity in the slow lane

Climate‐change adaptation focuses on conducting and translating research to minimize the dire impacts of anthropogenic climate change, including threats to biodiversity and human welfare. One adaptation strategy is to focus conservation on climate‐change refugia (that is, areas relatively buffered from contemporary climate change over time that enable persistence of valued physical, ecological, and sociocultural resources). In this Special Issue, recent methodological and conceptual advances in refugia science will be highlighted. Advances in this emerging subdiscipline are improving scientific understanding and conservation in the face of climate change by considering scale and ecosystem dynamics, and looking beyond climate exposure to sensitivity and adaptive capacity. We propose considering refugia in the context of a multifaceted, long‐term, network‐based approach, as temporal and spatial gradients of ecological persistence that can act as “slow lanes” rather than areas of stasis. After years of discussion confined primarily to the scientific literature, researchers and resource managers are now working together to put refugia conservation into practice.

Frontiers in Ecology and the Environment↗

USGS2020

Validating climate‐change refugia: Empirical bottom‐up approaches to support management actions

Efforts to conserve biodiversity increasingly focus on identifying climate‐change refugia – areas relatively buffered from contemporary climate change over time that enable species persistence. Identification of refugia typically includes modeling the distribution of a species’ current habitat and then extrapolating that distribution given projected changes in temperature and precipitation, or by mapping topographic features that buffer species from regional climate extremes. However, the function of those hypothesized refugia must be validated (or challenged) with independent data not used in the initial identification of the refugia. Although doing so would facilitate the incorporation of climate‐change refugia into conservation and management decision making, a synthesis of validation methods is currently lacking. We reviewed the literature and defined four methods to test refugia predictions. We propose that such bottom‐up approaches can lead to improved protected‐area designations and on‐the‐ground management actions to reduce influences from non‐climate stressors within potential refugia.

Idaho, Montana, Wyoming↗

USGS2015

Temperate forest health in an era of emerging megadisturbance

Although disturbances such as fire and native insects can contribute to natural dynamics of forest health, exceptional droughts, directly and in combination with other disturbance factors, are pushing some temperate forests beyond thresholds of sustainability. Interactions from increasing temperatures, drought, native insects and pathogens, and uncharacteristically severe wildfire are resulting in forest mortality beyond the levels of 20th-century experience. Additional anthropogenic stressors, such as atmospheric pollution and invasive species, further weaken trees in some regions. Although continuing climate change will likely drive many areas of temperate forest toward large-scale transformations, management actions can help ease transitions and minimize losses of socially valued ecosystem services.

Science↗

USGS2013

Alpine treeline of western North America: Linking organism-to-landscape dynamics

Although the ecological dynamics of the alpine treeline ecotone are influenced by climate, it is an imperfect indicator of climate change. Mechanistic processes that shape the ecotone—seed rain, seed germination, seedling establishment and subsequent tree growth form, or, conversely tree dieback—depend on microsite patterns. Growth forms affect wind and snow, and so develop positive and negative feedback loops that create these microsites. As a result, complex landscape patterns are generated at multiple spatial scales. Although these mechanistic processes are fundamentally the same for all forest-tundra ecotones across western North America, factors such as prior climate, underlying geology and geomorphology, and genetic constraints of dominant tree species lead to geographic differences in the responses of particular ecotones to climate change.

Physical Geography↗

USGS2010

Responding to climate change: A toolbox of management strategies: Chapter 11

Climate change and its effects are writ large across the landscape and in the natural and cultural heritage of parks and wilderness. They always have been and always will be. The sculpted walls of Yosemite National Park and the jagged scenery of the Sierra Nevada wilderness would not be as spectacular if periods of glaciation had not been followed by periods of deglaciation. High biodiversity in forests of the Great Smoky Mountains reflects a legacy of climate change, migrating species, and isolated climatic refugia. Fossils unearthed at Dinosaur National Monument reflect a time when the climate was very different than it is today, as do ruins left by peoples who practiced agriculture in places in the American Southwest where food production is not possible today. Over eons, climate change has molded the diversity of life and landscape in areas now protected as parks and wilderness.

Book chapter↗

USGS2010

Shifting environmental foundations: The unprecedented and unpredictable future: Chapter 4

As described in Chapter 2, protected area managers have been directed, through statutes and agency policy, to preserve natural conditions in parks and wilderness. Although preserving naturalness has always been a challenge for managers, there has never been much question about whether this is the right thing to do. But given what is known now about the pace and magnitude of ongoing global changes, the appropriateness of naturalness as a management goal must be reexamined. A host of anthropogenic environmental stressors are reshaping ecosystems, including those protected in parks and wilderness. Pollution is now ubiquitous worldwide, and invasive species are common in most landscapes. Habitats have become highly fragmented, and climatic changes are dramatically altering the abiotic conditions in which biota live. Given these changes, some attempts to restore and maintain naturalness may at best be ineffective; at worst, they could waste precious resources and even contribute to loss of some of the values that managers are trying to protect.

Book chapter↗

USGS2009

Guiding concepts for park and wilderness stewardship in an era of global environmental change

The major challenge to stewardship of protected areas is to decide where, when, and how to intervene in physical and biological processes, to conserve what we value in these places. To make such decisions, planners and managers must articulate more clearly the purposes of parks, what is valued, and what needs to be sustained. A key aim for conservation today is the maintenance and restoration of biodiversity, but a broader range of values are also likely to be considered important, including ecological integrity, resilience, historical fidelity (ie the ecosystem appears and functions much as it did in the past), and autonomy of nature. Until recently, the concept of “naturalness” was the guiding principle when making conservation‐related decisions in park and wilderness ecosystems. However, this concept is multifaceted and often means different things to different people, including notions of historical fidelity and autonomy from human influence. Achieving the goal of nature conservation intended for such areas requires a clear articulation of management objectives, which must be geared to the realities of the rapid environmental changes currently underway. We advocate a pluralistic approach that incorporates a suite of guiding principles, including historical fidelity, autonomy of nature, ecological integrity, and resilience, as well as managing with humility. The relative importance of these guiding principles will vary, depending on management goals and ecological conditions.

Frontiers in Ecology and the Environment↗