N. LeRoy Poff

N. LeRoy Poff
Colorado State University | CSU · Department of Biology

Doctor of Philosophy

About

253
Publications
188,748
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
53,801
Citations
Introduction
All of my research publications are available at http://rydberg.biology.colostate.edu/poff/PoffPublicationsPDF.htm
Additional affiliations
July 1997 - present
Colorado State University
Position
  • Professor (Full)
July 1997 - present
Colorado State University
Position
  • Professor (Full)

Publications

Publications (253)
Article
Full-text available
Species richness is greatest in the tropics, and much of this diversity is concentrated in mountains. Janzen proposed that reduced seasonal temperature variation selects for narrower thermal tolerances and limited dispersal along tropical elevation gradients [Janzen DH (1967) Am Nat 101:233–249]. These locally adapted traits should, in turn, promot...
Article
Full-text available
Managing freshwater resources sustainably under future climatic and hydrological uncertainty poses novel challenges. Rehabilitation of ageing infrastructure and construction of new dams are widely viewed as solutions to diminish climate risk, but attaining the broad goal of freshwater sustainability will require expansion of the prevailing water re...
Article
Full-text available
The ecological and evolutionary consequences of extreme events are poorly understood. Here, we tested predictions about species persistence and population genomic change in aquatic insects in 14 Colorado mountain streams across a hydrological disturbance gradient caused by a one in 500-year rainfall event. Taxa persistence ranged from 39 to 77% acr...
Article
Full-text available
A decade ago, scientists and practitioners working in environmental water management crystallized the progress and direction of environmental flows science, practice, and policy in The Brisbane Declaration and Global Action Agenda (2007), during the 10th International Riversymposium and International Environmental Flows Conference held in Brisbane,...
Article
Full-text available
The numerous environmental flows assessment methods that exist typically assume a stationary climate. Adaptive management is commonly put forward as the preferred approach for managing uncertainty and change in environmental flows. However, we contend that a simple adaptive management loop falls short of meeting the challenges posed by climate chan...
Article
Proposed hydropower dams at more than 350 sites throughout the Amazon require strategic evaluation of trade-offs between the numerous ecosystem services provided by Earth’s largest and most biodiverse river basin. These services are spatially variable, hence collective impacts of newly built dams depend strongly on their configuration. We use multi...
Article
Full-text available
Rivers are dynamic social-ecological systems that support societies and ecosystems in a multitude of ways, giving rise to a variety of user groups and competing interests. Environmental flows (e-flows) programs developed to protect riverine environments are often conceived by water managers and researchers. This is despite continued calls for incre...
Article
Numerous hydropower facilities are under construction or planned in tropical and subtropical rivers worldwide. While dams are typically designed considering historic river discharge regimes, climate change is likely to induce large-scale alterations in river hydrology. Here we analyze how future climate change will affect river hydrology, electrici...
Article
Full-text available
Frameworks exclusively considering functional diversity are gaining popularity, as they complement and extend the information provided by taxonomic diversity metrics, particularly in response to disturbance. Taxonomic diversity should be included in functional diversity frameworks to uncover the functional mechanisms causing species loss following...
Article
Full-text available
Many freshwater ecosystems are in decline because of anthropogenic disturbance including climate change, yet our understanding of ecological vulnerability to future conditions including climatic variation is limited. Understanding climate risks to freshwater ecosystems requires combining hydrological and ecological knowledge. While there have been...
Article
Full-text available
A fundamental gap in climate change vulnerability research is an understanding of the relative thermal sensitivity of ectotherms. Aquatic insects are vital to stream ecosystem function and biodiversity but insufficiently studied with respect to their thermal physiology. With global temperatures rising at an unprecedented rate, it is imperative that...
Article
Full-text available
Investment decisions about capital-intensive, long-lived infrastructure are challenging due to uncertainty about their future performance, particularly if the performance is sensitive to climate change. Such investments, like those made for water infrastructure, are rarely evaluated over their total operational lifetime, during which socio-economic...
Article
Environmental watering is frequently used to achieve specific ecological objectives, such as triggering spawning or seed germination. These short-term objectives are often met, but longer-term objectives, such as population growth, may not be, especially where multiple hydrological and non-hydrological factors influence success. We propose a framew...
Preprint
Full-text available
A fundamental gap in climate change vulnerability research is an understanding of the relative thermal sensitivity of tropical and temperate organisms. Aquatic insects are vital to stream ecosystem function and biodiversity. With global temperatures rising at an unprecedented rate, it is imperative that we understand how sensitive aquatic insects a...
Article
Full-text available
Resilience is increasingly recognized as an imperative for any prospect of sustainable development, as it relates to our ability to sustain human well-being and progress under the planetary and societal changes that we face now and into the future. Yet, we are ill-prepared to meet this challenge. We neither fully understand nor manage consistently...
Article
Full-text available
Anthropogenic threat maps are commonly used as a surrogate for the ecological integrity of rivers in freshwater conservation, but a clearer understanding of their relationships is required to develop proper management plans at large scales. Here, we developed and validated empirical models that link the ecological integrity of rivers to threat maps...
Article
Full-text available
Tropical montane rivers (TMR) are born in tropical mountains, descend through montane forests, and feed major rivers, floodplains, and oceans. They are characterized by rapid temperature clines and varied flow disturbance regimes, both of which promote habitat heterogeneity, high biological diversity and endemism, and distinct organisms’ life-histo...
Article
Climate change will increase water stress in many regions placing greater pressures on rivers to meet human and ecological water needs. Managing rivers experiencing water stress requires a fundamental understanding of how ecosystem processes and functions respond to natural and anthropogenic drivers of flow variability and change. The field of envi...
Article
Full-text available
More than a century of dam construction and water development in the western US has led to extensive ecological alteration of rivers. Growing interest in improving river function is compelling practitioners to consider ecological restoration when managing dams and water extraction. We developed an Ecological Response Model (ERM) for the Cache la Po...
Article
Full-text available
As the climate warms, we can’t restore waterways to pristine condition, but models can predict potential changes, argue Jonathan D. Tonkin, N. LeRoy Poff and colleagues. As the climate warms, we can’t restore waterways to pristine condition, but models can predict potential changes, argue Jonathan D. Tonkin, N. LeRoy Poff and colleagues. Fish that...
Article
Full-text available
Humans have altered the natural flow of rivers, adversely affecting biodiversity and the services that these watercourses provide. The mapping of millions of kilometres of rivers reveals the extent of human interference. Global maps of free-flowing rivers. Aerial view of the Irrawaddy river meandering through the landscape, Myanmar
Article
Full-text available
Resilience in river ecosystems requires that organisms must persist in the face of highly dynamic hydrological and geomorphological variations. Disturbance events such as floods and droughts are postulated to shape life history traits that support resilience, but river management and conservation would benefit from greater understanding of the emer...
Article
Full-text available
Species richness is greatest in the tropics, and much of this diversity is concentrated in mountains. Janzen proposed that reduced seasonal temperature variation selects for narrower thermal tolerances and limited dispersal along tropical elevation gradients [Janzen DH (1967) Am Nat 101:233-249]. These locally adapted traits should, in turn, promot...
Article
We examined the importance of temporal variability in top–down and bottom–up effects on the accumulation of stream periphyton, which are complex associations of autotrophic and heterotrophic microorganisms. Periphyton contributes to primary production and nutrient cycling and serves as a food resource for herbivores (grazers). Periphyton growth is...
Article
Full-text available
1. Extreme disturbances, those high magnitude events that are statistically rare in a particular system, may affect consumer resource use through multiple mechanisms , such as differential consumer mortality and modified resource availability and quality. Documenting the ecological importance of these rare events is difficult , but essential, as th...
Article
Full-text available
Food resource availability varies along gradients of elevation where riparian vegetative cover exerts control on the relative availability of allochthonous and autochthonous resources in streams. Still, little is known about how elevation gradients can alter the availability and quality of resources and how stream food webs respond. We sampled habi...
Conference Paper
Full-text available
Organismal traits determine how species perform and contribute to ecosystem functioning. Functional diversity indexes quantifies the value and range of these traits, which provides a mechanistic framework to understand community productivity and resilience to perturbations or invasion. We applied a multifaceted framework to quantify three primary c...
Data
Supplemental File for "Extreme Streams", Ecology Letters 2018
Article
Full-text available
Globally, large river systems have been extensively modified and are increasingly managed for a range of purposes including ecosystem services and ecological values. Key to managing rivers effectively are developing approaches that deal with uncertainty, are adaptive in nature, and can incorporate multiple stakeholders with dynamic feedbacks. Austr...
Article
Full-text available
Significant progress in environmental flow management has occurred in recent years due to several factors. These include governments committing to environmental flow programs, significant progress in scientific understanding, and environmental flow assessment methods that are cognizant of stakeholder participation and co-design. However, there rema...
Poster
Full-text available
Poster won the Top Scholars for University-Wide Graduate Programs
Article
Full-text available
• Human impacts on natural ecosystems are pervasive and will play out more severely as human populations and per capita resource use increase. Freshwater ecosystems are critical for human well‐being and experience a diverse range of human‐induced pressures. Most river systems throughout the world have much‐altered flow regimes. • The Murray–Darling...
Chapter
Full-text available
Although there has been significant progress in environmental water management across the globe, a number of challenges remain in the establishment and delivery of environmental water regimes on the ground—the implementation challenge. This final chapter focuses on the directions to achieve successful implementation of environmental water policies...
Chapter
There is a growing consensus that ecohydrological and hydraulic-habitat tools should be combined when predicting the ecological effects of water management scenarios in rivers. We describe the principles of these technical tools, their predictive power, and their role within more general approaches for defining environmental water regimes. Using re...
Chapter
Full-text available
Environmental flows assessment science focuses largely on defining how modified flow regimes (from water infrastructure and direct water abstraction) can be managed to conserve or restore societally desired ecological conditions in rivers and other wetland systems. The foundations of the science are based on hydroecological understanding and knowle...
Poster
Full-text available
Functional diversity quantifies the value and range of organismal traits that influence species performance and contribution to ecosystem functioning. Functional diversity (rather than simply taxonomic diversity) provides a mechanistic framework to understand community productivity and resilience to perturbations or invasion. Aquatic insect functio...
Article
Full-text available
Freshwater algal growth is often limited by the availability of nitrogen (N), phosphorus (P), or both nutrients (NP). For over 30 years, investigators have conducted nutrient-diffusing substrate (NDS) experiments to quantify algal nutrient limitation or co-limitation in rivers and streams. Previous meta-analyses of NDS have shown that algae are com...
Conference Paper
Full-text available
Functional diversity quantifies the value and range of organismal traits that influence species performance and contribution to ecosystem functioning. Functional diversity (rather than simply taxonomic diversity) provides a mechanistic framework to understand community productivity and resilience to perturbations or invasion. Aquatic insect functio...
Article
Full-text available
Janzen's extension of the climate variability hypothesis (CVH) posits that increased seasonal variation at high latitudes should result in greater temperature overlap across elevations, and favour wider thermal breadths in temperate organisms compared to their tropical counterparts. We tested these predictions by measuring stream temperatures and t...
Article
Full-text available
Montane environments around the globe are biodiversity 'hotspots' and important reservoirs of genetic diversity. Montane species are also typically more vulnerable to environmental change than their low-elevation counterparts due to restricted ranges and dispersal limitations. Here we focus on two abundant congeneric mayflies (Baetis bicaudatus and...
Article
Full-text available
Rivers provide many social and environmental services that benefit humanity. A critical role of water mangers is to prioritize water allocation options that trade off socioeconomic and hydro-ecological benefits in rivers. Methods for multi-criteria decision analysis (MCDA) provide a structured and systematic manner for researchers to aid in this pr...
Book
There is a growing consensus that ecohydrological and hydraulic-habitat tools should be combined when predicting the ecological effects of water management scenarios in rivers. We describe the principles of these technical tools, their predictive power, and their role within more general approaches for defining environmental water regimes. Using re...
Article
Full-text available
The Napo Basin in Ecuador is an important drainage of the Amazon Basin, the most biodiverse ecosystem for freshwater species. At the same time, this basin has conspicuous information gaps on its biodiversity patterns and human threats. Here, we estimated the diversity distribution patterns of freshwater vertebrates and invertebrates in the Napo Bas...
Article
Full-text available
The world's rivers are regulated by about 58,000 large dams (more than 15 m high) that provide water supplies for municipalities and irrigation, allow downstream navigation, and enable hydropower production ( 1 ). New dams are widely seen as sources of green energy. An estimated 75% of the world's potential hydropower capacity is unexploited ( 2 ),...
Article
Full-text available
Shifts in biodiversity and ecological processes in stream ecosystems in response to rapid climate change will depend on how numerically and functionally dominant aquatic insect species respond to changes in stream temperature and hydrology. Across 253 minimally perturbed streams in 8 ecoregions in the western US, we modeled the distribution of 88 i...
Article
Full-text available
The 'mountain passes are higher in the tropics' (MPHT) hypothesis posits that reduced climate variability at low latitudes should select for narrower thermal tolerances, lower dispersal and smaller elevational ranges compared with higher latitudes. These latitudinal differences could increase species richness at low latitudes, but that increase may...
Article
Full-text available
Relatively high β-diversity among aquatic insect communities inhabiting high-elevation streams is most commonly presumed to result from increased dispersal limitation between isolated mountaintop 'islands'. However, these elevational patterns of β-diversity have been predominately drawn from observed changes in community composition along single-th...
Article
Full-text available
River management involves satisfying societal preferences alongside environmental needs for a healthy river ecosystem. Environmental flows is a discipline that aims to define streamflow requirements that achieve desired social and ecological conditions in rivers. The ecological limits of hydrologic alteration (ELOHA) framework takes a regional appr...
Conference Paper
Climate nonstationarity and uncertainty raise important issues related to design and planning within the water sector. In addition, the water sector has acknowledged the need for improved methods of incorporating impacts of water resources development on ecosystems into project evaluation. We present a decision analytic approach to selecting flood...
Article
Temporal variability in water temperature plays an important role in aquatic ecosystems, yet the thermal regime of streams has mainly been described in terms of mean or extreme conditions. In this study, annual and diel variability in stream water temperature was described at 135 unregulated, gauged streams across the USA. Based on magnitude, ampli...
Article
Full-text available
Traits-based community analyses are receiving increasing attention. However, consistent interpretation of empirical results and ecological understanding in stream ecology are limited by ambiguous terminology. Furthermore, the measurement scales used to analyze trait data, especially ordinal-scale data, are often inappropriately applied. We identify...
Article
Management of riparian plant invasions across the landscape requires understanding the combined influence of climate, hydrology, geologic constraints and patterns of introduction. We measured abundance of nine riparian woody taxa at 456 stream gages across the western USA. We constructed conditional inference recursive binary partitioning models to...
Article
Full-text available
Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize flow regime at the expense of sediment regime. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley co...
Article
Full-text available
Article
Full-text available
Dams and water diversions can dramatically alter the hydraulic habitats of stream ecosystems. Predicting how water depth and velocity respond to flow alteration is possible using hydraulic models, such as Physical Habitat Simulation (PHABSIM); however, such models are expensive to implement and typically describe only a short length of stream (102...