Physical Sciences and Mathematics Commons^™

Impacts Of Climate Change On The Surface Water Balance Of The Central United States, 1984-2007, Bo Dong

School of Natural Resources: Dissertations, Theses, and Student Research

The climate system and the hydrologic cycle are strongly connected with each other. Understanding the interactions between these two systems is important, since variations in climate can trigger extensive changes in the hydrologic cycle, with significant impacts on agriculture, ecosystems, and society. Observations over the central U.S. in recent decades show numerous changes in climatic variables. This includes decreases in cloud cover and wind speed, increases in air temperature, and seasonal shifts in precipitation rate and rain/snow fraction. To assess the impacts of these variations in climate on the regional water cycle, a terrestrial ecosystem/land surface hydrologic model (Agro-IBIS) is …

Agricultural Landuse Change Impacts On Bioenergy Production, Avifauna, And Water Use In Nebraska's Rainwater Basin, Daniel R. Uden

School of Natural Resources: Dissertations, Theses, and Student Research

Agriculture is an economically important form of landuse in the North American Great Plains. Since 19^th Century European settlement, conversion of grasslands to rowcrops has increased food and bioenergy production, but has decreased wildlife habitat. Future agricultural landuse changes may be driven by alternative energy demands and regional climatic changes. Landuse change and its drivers could affect bioenergy production, wildlife populations and natural resources, and considering the potential impacts of impending changes in advance could assist with preparations for an uncertain future.

This study addressed how the conversion of marginally productive agricultural lands in the Rainwater Basin region of …

Complex Terrain Leads To Bidirectional Responses Of Soil Respiration To Inter-Annual Water Availability, Diego Andrés Riveros-Iregui, Brian L. Mcglynn, Ryan E. Emanuel, Howard E. Epstein

School of Natural Resources: Faculty Publications

Research on the terrestrial C balance focuses largely on measuring and predicting responses of ecosystem-scale production and respiration to changing temperatures and hydrologic regimes. However, landscape morphology can modify the availability of resources from year to year by imposing physical gradients that redistribute soil water and other biophysical variables within ecosystems. This article demonstrates that the well-established biophysical relationship between soil respiration and soil moisture interacts with topographic structure to create bidirectional (i.e., opposite) responses of soil respiration to inter-annual soil water availability within the landscape. Based on soil respiration measurements taken at a subalpine forest in central Montana, we …

Interannual And Spatial Impacts Of Phenological Transitions, Growing Season Length, And Spring And Autumn Temperatures On Carbon Sequestration: A North America Flux Data Synthesis, Chaoyang Wu, Alemu Gonsamo, Jing Ming Chen, Werner A. Kurz, David T. Price, Peter M. Lafleur, Rachhpal S. Jassal, Danilo Dragoni, Gil Bohrer, Christopher M. Gough, Shashi B. Verma, Andrew E. Suyker, J. William Munger

School of Natural Resources: Faculty Publications

Understanding feedbacks of ecosystem carbon sequestration to climate change is an urgent step in developing future ecosystem models. Using 187 site-years of flux data observed at 24 sites covering three plant functional types (i.e. evergreen forests (EF), deciduous forests (DF) and non-forest ecosystems (NF) (e.g., crop, grassland, wetland)) in North America, we present an analysis of both interannual and spatial relationships between annual net ecosystem production (NEP) and phenological indicators, including the flux-based carbon uptake period (CUP) and its transitions, degree-day-derived growing season length (GSL), and spring and autumn temperatures. Diverse responses were acquired between annul NEP and these indicators …

A Diatom Record Of Late Pliocene Cooling From The Ross Sea Continental Shelf, And-1b, Antarctica, Charlotte Sjunneskog, Diane Winter

ANDRILL Research and Publications

A late Pliocene – early Pleistocene, 2.9–2.0Ma, diatom record from the Antarctic Geological Drilling Program (ANDRILL) MIS drillcore AND-1B is presented. This core, recovered from beneath the Ross Ice Shelf south of Ross Island, comprises multiple diatomaceous-sediment units deposited during interglacial periods with open water over the core site. These represent interglacial phases of orbitally paced climate cycles and are punctuated by glacial advances. Extant diatom assemblages have limited presence in the late Pliocene record, which makes environmental interpretation less straight forward. We employ modern ecological data in combination with late Pliocene to present variation in diatom assemblages across the …

Diversity And Distribution Of Mongolian Fish: Recent State, Trends And Studies, Yuri Dgebuadze, Bud Mendsaikhan, Ayurin Dulmaa

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

The studies in recent years (2000-2011) have allowed to make more precise the list and ranges of Mongolian fish. This is connected with new findings as well as the continuing process of invasion of alien species. Climate change and increase of human impact transformed ranges and local distribution of fish during last 30 years. Bias on ratio of ecological guilds, number of pathological findings are increasing, and declining of local diversity, rate of growth and fecundity of many species of fish are observed. In the course of long-term observation was confirmed periodically drying of waters of the Central Asian Lake …

Global Air Temperature Variability Independent Of Sea-Surface Temperature Influences, Andrew C. Comrie, Gregory J. Mccabe

United States Geological Survey: Staff Publications

Mean global surface air temperature (SAT) and sea surface temperature (SST) display substantial variability on timescales ranging from annual to multi-decadal. We review the key recent literature on connections between global SAT and SST variability. Although individual ocean influences on SAT have been recognized, the combined contributions of worldwide SST variability on the global SAT signal have not been clearly identified in observed data.Weanalyze these relations using principal components of detrended SST, and find that removing the underlying combined annual, decadal, and multi-decadal SST variability from the SAT time series reveals a nearly monotonic global warming trend in SAT since …

Hurricane Disturbance And Recovery Of Energy Balance, Co2 Fluxes And Canopy Structure In A Mangrove Forest Of The Florida Everglades, Jordan G. Barr, Vic Engel, Thomas J. Smith, José D. Fuentes

United States Geological Survey: Staff Publications

Eddy covariance (EC) estimates of carbon dioxide (CO2) fluxes and energy balance are examined to investigate the functional responses of a mature mangrove forest to a disturbance generated by Hurricane Wilma on October 24, 2005 in the Florida Everglades. At the EC site, high winds from the hurricane caused nearly 100% defoliation in the upper canopy and widespread tree mortality. Soil temperatures down to −50 cm increased, and air temperature lapse rates within the forest canopy switched from statically stable to statically unstable conditions following the disturbance. Unstable conditions allowed more efficient transport of water vapor and CO₂ from …

Responses Of Antarctic Pack-Ice Seals To Environmental Change And Increasing Krill Fishing, Jaume Forcada, Philip N. Trathan, Peter L. Boveng, Ian L. Boyd, Jennifer M. Burns, Daniel P. Costa, Michael Fedak, Tracey L. Rogers, Colin J. Southwell

United States Department of Commerce: Staff Publications

The compound effects of changing habitats, ecosystem interactions, and fishing practices have implications for the management of Antarctic krill and conservation of its predators. For Antarctic pack-ice seals, an important group of krill predators, we estimate the density and krill consumption in the West Antarctic Peninsula (WAP)–Western Weddell Sea area, the main fishery region; and we consider long-term changes in suitable pack-ice habitat, increased fishing pressure and potential krill declines based upon predictions from declines in sea ice cover. More than 3 million crabeater seals consumed over 12 million tonnes of krill each year. This was approximately 17% of the …