Treesearch

Projections of future climate were selected for four well-established general circulation models (GCMs) forced by each of three greenhouse gas (GHG) emissions scenarios recommended by the Intergovernmental Panel on Climate Change (IPCC), namely scenarios A2, A1B, and B1 of the IPCC Special Report on Emissions Scenarios. Monthly data for the period 1961-2100 were downloaded mainly from the web portal of the Coupled Model Intercomparison Project (Phase 3) of the Program for Climate Model Diagnosis and Intercomparison, and subsets of data covering North America were extracted. Scenario data...

Nursery plants are in a period of high risk from the time they leave the protected environment of the nursery to when they are outplanted. During handling and shipping, nursery stock may be exposed to many damaging stresses, including extreme temperatures, desiccation, mechanical injuries, and storage molds. This is also the period of greatest financial risk, because nursery plants have reached their maximum value right before shipping (Paterson et al., 2001). Adams and Patterson (2004) concluded that improper handling of nursery stock had more impact on plant quality than the type of...

Restoration is one of five focal areas of the Grassland, Shrubland and Desert Ecosystems Science Program (GSD). Our program mission is to develop and deliver knowledge and tools that will help to sustain and restore grasslands, shrublands and deserts threatened by invasive species, disturbances, urban pressures and climate change. Scientists in our program develop methods for restoring ecosystems with native plants, assess genetic variation and resilience among plant subspecies, and design and test restoration treatments to determine best restoration treatment practices. Studies focus on...

Current guidelines for predicting increases in shear stress in open-channel bends were developed from investigations that were primarily prismatic in cross section. This study provides possible increases in shear stress relative to approach flow conditions resulting from planimetric and topographic geometric features. Boundary shear stress estimates were determined by several methods utilizing acoustic Doppler velocimeter (ADV) and Preston tube data in a physical model of a full meander representing native topographic features found in the Middle Rio Grande. Methods examined include: the...

Hydraulic conditions associated with channel bends in meandering rivers include secondary, helical currents, mass shift of flow to the outside of the bend, and increased erosion along the outer streambank. Such outer-bank erosion may result in undesired plan-form migration of the stream course, placing valuable land holdings or infrastructure in jeopardy. A type of in-stream transverse rock structure, the vane dike, has been installed in field scenarios to mitigate problematic hydraulics associated with migrating river bends. Flows around vanes and similar structures have been modeled...

The Middle Rio Grande is a 29-mi reach of the Rio Grande River in central New Mexico that extends from downstream of Cochiti Dam to Bernalillo, New Mexico. A series of anthropogenic factors including the construction of flood control levees and Cochiti Dam have altered the historically-braided morphology of the Middle Rio Grande to a more sinuous, degrading reach, with less overall channel migration within a natural floodplain area. Concentration of flow within an incised channel has caused areas of bank erosion and threatened riverside infrastructure, farmland productivity, irrigation...

The 29 papers in this proceedings are divided into the main organized sessions of the 16th Wildland Shrub Symposium, including the plenary session to introduce the theme of threats to shrubland ecosystem integrity, impacts of energy development and reclamation on ecosystem function, invasive plant ecology. wildlife habitats: impacts and restoration opportunities, historical perspectives in shrublands, ecosystem threats due to fire in the Mojave Desert, and modeling and monitoring of shrubland ecosystems. An overarching goal of the symposium was to make linkages between research and management.

In a world where the metrics of the carbon economy have become a major issue, it may come as a surprise that intact cold desert shrublands can sequester significant amounts of carbon, both as biomass and in the form of SOC (soil organic carbon). Xerophytic shrubs invest heavily in belowground biomass, placing fixed carbon in an environment where it turns over only very slowly. In order for humans to gain this important ecosystem service, desert shrublands must be kept intact and prevented from frequent burning. The biggest threat to shrubland integrity is the invasion of exotic annual...

Modeling of aquatic microhabitat in streams has been typically done over short channel reaches using one-dimensional simulations, partly because of a lack of high resolution. subaqueous topographic data to better define model boundary conditions. The Experimental Advanced Airborne Research Lidar (EAARL) is an airborne aquatic-terrestrial sensor that allows simultaneous high resolution surveying in both environments over spatial domains of up to several hundred kilometers of stream length. Here we use the USGS two-dimensional finite difference fluid dynamics model, FaSTMECH, run under the...

Thermal regimes in rivers and streams are fundamentally important to aquatic ecosystems and are expected to change in response to climate forcing as the Earth’s temperature warms. Description and attribution of stream temperature changes are key to understanding how these ecosystems may be affected by climate change, but difficult given the rarity of long-term monitoring data. We assembled 18 temperature time-series from sites on regulated and unregulated streams in the northwest U.S. to describe historical trends from 1980–2009 and assess thermal consistency between these stream categories...