Treesearch

In this technical note, a steady-state analytical solution of concentrations of a parent solute reacting to a daughter solute, both of which are undergoing transport and multirate mass transfer, is presented. Although the governing equations are complicated, the resulting solution can be expressed in simple terms. A function of the ratio of concentrations, In (daughter/parent + P), can be used as a metric of mass transfer and reaction if the reactions are mostly confined to the immobile domain, where P is the ratio of production of daughter to decay of parent. This metric is applied with...

Most spatially explicit hydrologic models require estimates of air temperature patterns. For these models, empirical relationships between elevation and air temperature are frequently used to upscale point measurements or downscale regional and global climate model estimates of air temperature. Mountainous environments are particularly sensitive to air temperature estimates as spatial gradients are substantial, and air temperature plays a critical role in snow-related processes. We use a distributed, coupled ecohydrologic model to compare estimates of streamflow, snowmelt, transpiration,...

What are natural landscapes? Are they “out there,” separate from people, or are they creations of our own perception? An exploration of artistic visions of landscape on the one hand and the development of ecology as a self-conscious science on the other suggests that for nearly 150 years ecology has been conditioned by romantic, picturesque portrayals of landscape. Landscape (as landscab) originally implied people living within and shaping a capricious nature, but rapidly evolved to landtskip: natural scenery reflecting a balance of nature viewed from the outside. Despite repeated scientifi...

Pocket gophers (Geomyidae) are major agents of disturbance in North American grasslands. Gopher mounds bury existing plants and influence community structure through various mechanisms. However, in mountain meadows that experience winter snowpack, gophers also create winter castings, smaller tube-shaped deposits, previously ignored in studies of plant–gopher disturbance relationships. We studied the influences of the Mazama pocket gopher (Thomomys mazama Merriam, 1897) in montane meadows of the Oregon Cascades, quantifying community patterns at larger spatial scales than previously studied...

Although the word commitment is prevalent in conservation biology literature and despite the importance of people’s commitment to the success of conservation initiatives, commitment as a psychological phenomenon and its operation in specific conservation behaviors remains unexplored. Despite increasing calls for conservation psychology to play a greater role in meeting conservation goals, applications of the psychological sciences to specific conservation behaviors, illustrating their utility to conservation practice, are rare. We examined conservation volunteers’ motivations and commitment...

Multi-instance multi-label learning (MIML) is a framework for supervised classification where the objects to be classified are bags of instances associated with multiple labels. For example, an image can be represented as a bag of segments and associated with a list of objects it contains. Prior work on MIML has focused on predicting label sets for previously unseen bags. We instead consider the problem of predicting instance labels while learning from data labeled only at the bag level. We propose a regularized rank-loss objective designed for instance annotation, which can be instantiated...

Flow and temperature are strongly linked environmental factors driving ecosystem processes in streams. Stream temperature maxima (Tmax_w) and stream flow minima (Qmin) can create periods of stress for aquatic organisms. In mountainous areas, such as western North America, recent shifts toward an earlier spring peak flow and decreases in low flow during summer/fall have been reported. We hypothesized that an earlier peak flow could be shifting the timing of low flow and leading to a decrease in the interval between Tmax_w and Qmin. We also examined if years with extreme low Qmin were...

1. Temperature is a major driver of ecological processes in stream ecosystems, yet the dynamics of thermal regimes remain poorly described. Most work has focused on relatively simple descriptors that fail to capture the full range of conditions that characterise thermal regimes of streams across seasons or throughout the year. 2. To more completely describe thermal regimes, we developed several descriptors of magnitude, variability, frequency, duration and timing of thermal events throughout a year. We evaluated how these descriptors change over time using long-term (1979–2009), continuous...

We used a new ecohydrological model, Visualizing Ecosystems for Land Management Assessments (VELMA), to analyze the effects of forest harvest on catchment carbon and nitrogen dynamics. We applied the model to a 10 ha headwater catchment in the western Oregon Cascade Range where two major disturbance events have occurred during the past 500 years: a stand-replacing fire circa 1525 and a clear-cut in 1975. Hydrological and biogeochemical data from this site and other Pacific Northwest forest ecosystems were used to calibrate the model. Model parameters were first calibrated to simulate the...

Thawing permafrost represents a poorly understood feedback mechanism of climate change in the Arctic, but with a potential impact owing to stored carbon being mobilized1–5. We have quantified the long-term loss of carbon (C) from thawing permafrost in Northeast Greenland from 1996 to 2008 by combining repeated sediment sampling to assess changes in C stock and >12 years of CO2 production in incubated permafrost samples. Field observations show that the activelayer thickness has increased by >1 cm yr-1 but thawing has not resulted in a detectable decline in C stocks. Laboratory mineralizatio...