Oregon State University

About: Oregon State University is a education organization based out in Corvallis, Oregon, United States. It is known for research contribution in the topics: Population & Gene. The organization has 28192 authors who have published 64044 publications receiving 2634108 citations. The organization is also known as: Oregon Agricultural College & OSU.

13C content of ecosystem respiration is linked to precipitation and vapor pressure deficit

Abstract: Variation in the carbon isotopic composition of ecosystem respiration (δ 13 C R ) was studied for 3 years along a precipitation gradient in western Oregon, USA, using the Keeling plot approach. Study sites included six coniferous forests, dominated by Picea sitchensis, Tsuga heterophylla, Pseudotsuga menziesii, Pinus ponderosa, and Juniperus occidentalis, and ranged in location from the Pacific coast to the eastern side of the Cascade Mountains (a 250-km transect). Mean annual precipita- tion across these sites ranged from 227 to 2,760 mm. Overall δ 13 C R varied from -23.1 to -33.1‰, and within a single forest, it varied in magnitude by 3.5-8.5‰. Mean annual δ 13 CR differed significantly in the forests and was strongly correlated with mean annual precipitation. The carbon isotope ratio of carbon stocks (leaves, fine roots, litter, and soil organic matter) varied similarly with mean precipitation (more positive at the drier sites). There was a strong link between δ13C R and the vapor saturation deficit of air ( vpd) 5-10 days earlier, both across and within sites. This relationship is consistent with stomatal regulation of gas exchange and associated changes in photosynthetic carbon isotope discrimination. Recent freeze events caused significant deviation from the δ13C R versus vpd relationship, resulting in higher than expected δ 13 CR values.

Triads in supply networks: theorizing buyer–supplier–supplier relationships

Abstract: Past studies in supply chain management have focused on dyadic relationships (e.g., buyer–supplier), as all relationships in a network begin with a dyad. However, dyads do not capture the essence of a network. We posit in this paper that triads are the fundamental building blocks of a network. To begin considering triads in supply networks, we build on two extant bodies of literature — the buyer–supplier relationship and supplier–supplier relationship literature which offer us the context of buyer–supplier–supplier triads. By doing so, we are taking the first step toward cracking the internal dynamics of triads in supply networks. To build theoretical propositions, we apply balance theory and the structural-hole concept. We identify nine triadic archetypes of buyer–supplier–supplier relationships and state key propositions that aid in decision making in supply networks.

It's the nature of the beast: The influence of knowledge and intentions on learning and teaching nature of science

Abstract: This study examined the knowledge, intentions, and instructional practices of two beginning secondary science teachers as they learned the subject matter of nature of science (NOS) and attempted to teach NOS during their student teaching experience and during their first year of full-time teaching. This is a case study comparison of two success stories. However, the reasons for and levels of success are as varied as the factors that influence teaching practice. Details of the participants' progression, along with descriptions of the challenges they faced in the learning and teaching of NOS offer insight into the complexity of the fulfillment of one's instructional intentions. The results of the study suggest that depth of NOS understanding, subject-matter knowledge, and the perceived relationship between NOS and science subject matter affected the participants' learning and teaching of NOS. The views of NOS as an inherent part of all science content or as “the nature of the beast” facilitated the inclusion of NOS within traditional science content lessons. The participant with the more extensive science background, who also held well-developed NOS views, was better able to address NOS throughout his teaching. His subject-matter knowledge enabled him to use a variety of examples to enhance NOS instruction. The other participant's more limited subject-matter knowledge and compartmentalized view of NOS seemed to inhibit her incorporation of relevant NOS topics within a traditional science content. The importance of subject-matter knowledge, NOS knowledge, and NOS instruction intentions to the development of pedagogical content knowledge for NOS and the actualization of intentions in the classroom are discussed. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 205–236, 2002

Where does water go when it rains? Moving beyond the variable source area concept of rainfall-runoff response

Abstract: Where does water go when it rains? What flow path does it take to the stream? How long does it reside in the catchment? These questions were articulated by John Hewlett within the context of his variable source area (VSA) concept almost 40 years ago (Hewlett and Hibbert, 1967). Today, we still grapple with these often vexing questions—now using new tools and approaches, but, as then, still searching for answers. Rapid progress is being made on the rainfallrunoff modelling front in catchment hydrology vis-a-vis parameter estimation techniques, model uncertainty analysis, examination of parameter identifiability in our models, downward approaches to hydrologic prediction, etc. (Beven 2001; Sivapalan, 2003). However, I wonder if we have somewhat neglected updating our understanding of the rainfall-runoff process and how this informs our needed model structures and response to these three basic questions central to our conceptualization of how catchments work? One could argue that our sharpening perception of water source, flowpath and age in upland headwater catchments is radically different to what the framers of the VSA theory thought a half century ago (i.e. Hewlett in the USA, Cappus in France and Tsukamoto in Japan). Our best models still rely on mechanistic notions underlying the VSA, including saturation excess overland flow and subsurface stormflow (I will avoid mentioning how our operational models often are based on another whole older generation of streamflow generation concepts related exclusively to Horton!). The VSA concept has been distilled into our widely used research model structures by collapsing the process complexity into simple mathematical assumptions of things like the decline in saturated hydraulic conductivity with depth, steady-state catchment water table response, topographically defined water flowpaths and linear wetting and drying from the valley bottom upwards to the ridge (depending upon storm size, intensity and antecedent wetness conditions). Much discussion is now devoted in the modelling literature towards the balance between practical simplifications of the VSA details and justifiable model complexity. This commentary takes a critical look at our process underpinning by discussing new field evidence of where water goes when it rains that directly challenges the status quo. New model structures informed by this new process understanding are then discussed in the context of how data