Geology topics

P.C. Trenham

Publications and source records attributed to P.C. Trenham.

3 recordsLinked to original sources

USGS2005

Estimated ultraviolet radiation doses in wetlands in six national parks

Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia (Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/Kings Canyon (Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools, field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B dose estimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks was 19.3 W-h m −2 (range of 3.4–32.1 W-h m −2 ). The mean dose was lowest in Acadia (13.7 W-h m −2 ) and highest in Rocky (24.4 W-h m −2 ). Doses were significantly different among all parks. These wetland doses correspond to UV-B flux of 125.0 μW cm −2 (range 21.4–194.7 μW cm −2 ) based on a day length, averaged among all parks, of 15.5 h. Dissolved organic carbon (DOC), a key determinant of water-column UV-B flux, ranged from 0.6 (analytical detection limit) to 36.7 mg C L −1 over all wetlands and parks, and reduced potential maximal UV-B doses at 1-cm depth by 1%–87 %. DOC concentration, as well as its effect on dose, was lowest in Sequoia and highest in Acadia (DOC was equivalent in Acadia, Glacier, and Rocky). Landscape reduction of potential maximal UV-B doses ranged from zero to 77% and was lowest in Sequoia. These regional differences in UV-B wetland dose illustrate the importance of considering all aspects of exposure in evaluating the potential impact of UV-B on aquatic organisms.

Acadia National Park, Glacier National Park, Great↗

USGS2005

Distribution patterns of lentic-breeding amphibians in relation to ultraviolet radiation exposure in western North America

An increase in ultraviolet-B (UV-B) radiation has been posited to be a potential factor in the decline of some amphibian population. This hypothesis has received support from laboratory and field experiments showing that current levels of UV-B can cause embryo mortality in some species, but little research has addressed whether UV-B is influencing the distribution of amphibian populations. We compared patterns of amphibian presence to site-specific estimates of UV-B dose at 683 ponds and lakes in Glacier, Olympic, and Sequoia–Kings Canyon National Parks. All three parks are located in western North America, a region with a concentration of documented amphibian declines. Site-specific daily UV-B dose was estimated using modeled and field-collected data to incorporate the effects of elevation, landscape, and water-column dissolved organic carbon. Of the eight species we examined ( Ambystoma gracile, Ambystoma macrodactylum, Bufo boreas, Pseudacris regilla, Rana cascadae, Rana leuteiventris, Rana muscosa, Taricha granulosa ), two species ( T. granulosa and A. macrodactylum ) had quadratic relationships with UV-B that could have resulted from negative UV-B effects. Both species were most likely to occur at moderate UV-B levels. Ambystoma macrodactylum showed this pattern only in Glacier National Park. Occurrence of A. macrodactylum increased as UV-B increased in Olympic National Park despite UV-B levels similar to those recorded in Glacier. We also found marginal support for a negative association with UV-B for P. regilla in one of the two parks where it occurred. We did not find evidence of a negative UV-B effect for any other species. Much more work is still needed to determine whether UV-B, either alone or in concert with other factors, is causing widespread population losses in amphibians.

California, Montana, Washington↗

USGS2004

Designing monitoring programs in an adaptive management context for regional multiple species conservation plans

Increasing numbers of regional, multiple species conservation plans have been developed in California since the early 1990s. However, building effective monitoring and adaptive management programs to support these plans has remained a challenge. In addition to collecting data on the status of resources and the results of management actions, monitoring programs for these plans need to resolve critical uncertainties and channel information into effective decisionmaking. Because of the broad goals of many regional conservation plans, monitoring programs need to address ecosystem integrity and biodiversity while also tracking species ?covered? by plan permits. In this document we provide a step-by-step procedure for developing effective monitoring programs in an adaptive management context. The guidance provided here has been gleaned from experience with large multiple species plans in southern California. The process begins with clearly defining program objectives, partitioning the program into manageable but meaningful pieces, and developing management-oriented conceptual models of system function. Then, based on the objectives and conceptual models, monitoring recommendations and critical uncertainties can be identified and a coordinated program designed. We include practical examples and insights from programs in southern California and discuss the evolution of monitoring and adaptive management programs through three successive stages: 1) inventorying resources and identifying relationships; 2) pilot testing of long-term monitoring and resolving critical management uncertainties; and 3) implementing long-term monitoring and adaptive management. Ultimately, the success of regional conservation planning depends on the ability of monitoring programs to confront the challenges of adaptively managing and monitoring complex ecosystems and diverse arrays of sensitive species.

Technical Report↗