Colorado State University

About: Colorado State University is a education organization based out in Fort Collins, Colorado, United States. It is known for research contribution in the topics: Population & Laser. The organization has 31430 authors who have published 69040 publications receiving 2724463 citations. The organization is also known as: CSU & Colorado Agricultural College.

Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flows

Abstract: Summary 1. In an effort to develop quantitative relationships between various kinds of flow alteration and ecological responses, we reviewed 165 papers published over the last four decades, with a focus on more recent papers. Our aim was to determine if general relationships could be drawn from disparate case studies in the literature that might inform environmental flows science and management. 2. For all 165 papers we characterised flow alteration in terms of magnitude, frequency, duration, timing and rate of change as reported by the individual studies. Ecological responses were characterised according to taxonomic identity (macroinvertebrates, fish, riparian vegetation) and type of response (abundance, diversity, demographic parameters). A ‘qualitative’ or narrative summary of the reported results strongly corroborated previous, less comprehensive, reviews by documenting strong and variable ecological responses to all types of flow alteration. Of the 165 papers, 152 (92%) reported decreased values for recorded ecological metrics in response to a variety of types of flow alteration, whereas 21 papers (13%) reported increased values. 3. Fifty-five papers had information suitable for quantitative analysis of ecological response to flow alteration. Seventy per cent of these papers reported on alteration in flow magnitude, yielding a total of 65 data points suitable for analysis. The quantitative analysis provided some insight into the relative sensitivities of different ecological groups to alteration in flow magnitudes, but robust statistical relationships were not supported. Macroinvertebrates showed mixed responses to changes in flow magnitude, with abundance and diversity both increasing and decreasing in response to elevated flows and to reduced flows. Fish abundance, diversity and demographic rates consistently declined in response to both elevated and reduced flow magnitude. Riparian vegetation metrics both increased and decreased in response to reduced peak flows, with increases reflecting mostly enhanced non-woody vegetative cover or encroachment into the stream channel. 4. Our analyses do not support the use of the existing global literature to develop general, transferable quantitative relationships between flow alteration and ecological response; however, they do support the inference that flow alteration is associated with ecological change and that the risk of ecological change increases with increasing magnitude of flow alteration. 5. New sampling programs and analyses that target sites across well-defined gradients of flow alteration are needed to quantify ecological response and develop robust and general flow alteration–ecological response relationships. Similarly, the collection of pre- and post-alteration data for new water development programs would significantly add to our basic understanding of ecological responses to flow alteration.

Hydraulic Conductivity and Diffusivity: Laboratory Methods

Abstract: This chapter describes several laboratory methods of determining the hydraulic conductivity and hydraulic diffusivity. Water moves through soil in response to various forces acting upon it. The chemical species water may be transported due to bulk movement of the liquid phase or soil solution, or it may be transported by diffusion relative to the mean motion of the liquid phase. The chapter deals with bulk movement, under isothermal conditions, of the liquid phase in response to mechanical driving forces. However, the transport of water in the gas phase by vapor diffusion will be included in the measured hydraulic conductivity and diffusivity, especially at low water contents. The concept of parameter identification has been applied to the determination of the parameters in the hydraulic conductivity and water retention functions. The method involves the measurement of some aspect of the response of a soil water flow system to a set of applied boundary conditions.

Determinants of woody cover in African savannas

Abstract: Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties1–3. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover1,2,4,5, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than ,650mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered ‘stable' systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of ,650mm, savannas are ‘unstable' systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation6 may considerably affect their distribution and dynamics.

Carbon nanotubule membranes for electrochemical energy storage and production

Abstract: Ensembles of aligned and monodisperse tubules of graphitic carbon can be prepared by a templating method1,2,3,4 that involves the chemical-vapour deposition of carbon within the pores of alumina membranes5,6,7. Tubules with diameters as small as 20 nm have been prepared in this way7,8. The carbon comprising these tubules can be transformed from a disordered material to very highly ordered graphite5. Here we show that template-synthesized carbon tubules can be fabricated as free-standing nanoporous carbon membranes, and that narrower, highly ordered graphitic carbon nanotubes can be prepared within the membrane's tubules. Both the outer and the inner tubules are electrochemically active for intercalation of lithium ions, suggesting possible applications in lithium-ion batteries9,10. The membranes can also be filled with nanoparticles of electrocatalytic metals and alloys. Such catalyst-loaded membranes can be used to electrocatalyse O2 reduction and methanol oxidation, two reactions of importance to fuel-cell technology.

Corporate social responsibility and marketing: An integrative framework

Abstract: This article introduces a conceptualization of corporate social responsibility (CSR) that emphasizes the role and potential contribution of the marketing discipline. The proposed framework first depicts CSR initiatives as the actions undertaken to display conformity to both organizational and stakeholder norms. Then, the article discusses the managerial processes needed to monitor, meet, and even exceed, stakeholder norms. Finally, the analysis explains how CSR initiatives can generate increased stakeholder support.