A spectral framework for forecasting near term inland fisheries in the Mekong River under climate change

John Sabo, a visiting researcher from Arizona State University, will be presenting this week’s roundtable! He will be telling us about his work in the ecologically and economically important Mekong River Basin. We will be continuing the climate change theme from last week’s talk, but moving onto its impacts on fisheries instead. He will also discuss how dams have impacted the river and fisheries.

Abstract:  Inland capture fisheries on the Mekong River provide a majority of the animal protein and vitamin A to the diets of over 40M people in the Lower Mekong River Basin.  The productivity of this fishery is fueled by the monsoon flood pulse which creates wetlands the size of small US states in Cambodia and Vietnam.  The region is experiencing rapid development, including the planning and impending construction of over 20 hydropower facilities, some already built.  Climate change will also likely change the intensity and timing of the South Asian Monsoon, with implications for the extent of the ensuing flood pulse and the fishery that depends on it.  In this roundtable I will address two topics.  First, I present the results from a century scale analysis of change in hydrologic variation and key aspects of the flood pulse on the Mekong River including an assessment of current dams.  This analysis is done within a novel spectral framework that allows for identification of baseline stationarity and decomposition of the linear, seasonal and stochastic components of change in daily discharge.  Second I link spectral measures of hydrologic variation to catch data from the fishery using a 15-year dataset of the Dai fishery on the Tonle Sap River (Cambodia) and a second time series approach—a multivariate autoregressive state space (MARSS) model.   The spectral-MARSS framework is then used to forecast the fishery under near time climate change.   Daily discharge variation and key aspects of the flood pulse have been experiencing natural change for over a century. Existing dams have modified discharge in spite of a shifting baseline.  Fisheries catch varies with several spectral measures of daily discharge variation.  Surprisingly, low flows have equal if not higher positive effect sizes than high flows on catch in this flood pulse system and spectral measures outperform “first moment” measures of flood pulse extent.  Moreover, antecedent hydrology—the flood drought sequence from the previous 1-2 years—significantly affects current catch in the fishery.  These results suggest that the spectral-MARSS framework may provide a robust tool for forecasting fisheries production in the future.

Trey Riel 2

Assessing effects of climate change on ponderosa pine forests in California’s Sierra Nevada

Ian McCullough is from the UCSB Bren school and will be presenting on his PhD research. Join us for this timely talk on climate change and California forests.

Co-author credits: Frank Davis, Lorraine Flint, Alan Flint, John Dingman

Abstract: Climate change has emerged as a potent threat to forests worldwide, resulting in heightened concern for the sustainability of timber resources, ecosystem services, structure and function. In this study, we investigate the effects of long-term climate change on the growth and distribution of ponderosa pine in the Sierra Nevada of California using tree-rings and statistically downscaled climate models. We focused initial efforts on a small, declining population at Tejon Ranch, near the species’ southern range limit. Subsequently, we incorporated published tree-ring chronologies from the International Tree-Ring Data Bank to assess climate-growth relationships along a Sierra Nevada latitudinal gradient. Climatic controls on growth have varied historically across the gradient. Although precipitation was the primary limiting factor at all sites, more northern sites were more sensitive to fall temperatures, whereas southern sites were more sensitive to climatic water deficits (measure of unmet evaporative demand for water). Given that trees cannot live where they cannot grow, we are currently exploring ways to use the climate-growth relationship to infer the potential future distribution of ponderosa pine based on locations of favorable growing habitat.


Extending risk and cumulative impacts assessment to include life stage considerations

Roundtable for next week will be presented by Emma Hodgson, a graduate student in the School of Aquatic and Fishery Sciences at the University of Washington, Seattle.


Marine species are experiencing a suite of novel stressors from anthropogenic activities that have impacts at multiple scales. Ecological risk assessment is commonly used to judge the consequence of novel stressors to species, but usually without consideration of the life history of organisms. Most marine species vary throughout their life history in their spatio-temporal distributions in the water column, their responses to external pressures, and their level of contribution to the population overall. Better incorporating our understanding of those differences between life stages provides an opportunity to advance our understanding of the consequences of stress at the population level. This work advances approaches to ecological risk assessment and cumulative impacts assessment by explicitly incorporating life stage exposure, sensitivity, and importance to population growth rate.

Emma in the wild

Emma in the wild

What goes up must come down: Implications of increasing productivity for aquatic food webs    

Join us for our June 3rd Roundtable with Colette Ward, who will be presenting on her PhD research!

What goes up must come down: Implications of increasing productivity for aquatic food webs    

Ecologists have long sought to understand the effects of productivity on community structure, and the question remains of pressing importance given contemporary patterns of anthropogenic change. Extensive debate has revolved around bottom-up and top-down hypotheses for community response to productivity, with the latter now dominating our conceptualization of this question in aquatic ecosystems. Key to this discourse is the principle that, in the absence of bottlenecks to vertical energy flux, top-down control is a fundamental response of communities to rising productivity and becomes stronger across productivity gradients.  Here I show that this principle, when projected onto commonly occurring food web motifs (community modules), readily predicts common violations of fundamental assumptions of classical top-down hypotheses, and, by extension, that community responses to rising productivity are not conserved across productivity gradients but are instead context-dependent.

Using 23 large marine food webs I show that food web responses to productivity arise from within-food chain processes at low productivity and increasingly from multi-chain processes with increasing productivity.  This shift unfolds as primary production is increasingly directed into bottom-up controlled detritus channels, subsidizing generalist predators, which in turn exert top-down control on herbivores in an apparent trophic cascade.  Using theory and empirical data from whole lake and marine food webs I show that the effect of productivity on food chain length (FCL) is also context-dependent: FCL should increase over ranges of low productivity and decline over ranges of high productivity as increasingly top-heavy biomass pyramids favor omnivory; at intermediate productivity, FCL should be driven instead by ecosystem size.  Overall this work suggests that, in contrast to conventional thinking, mechanisms of aquatic community response to productivity are not conserved across productivity gradients and are instead readily predicted by a simple community module framework.

Colette in the field

Colette in the field

KNB data search tool demonstration

UPDATE: Here are the links Lauren mentioned in her talk.

Slides: https://docs.google.com/a/nceas.ucsb.edu/presentation/d/1zdZLh3YRIXWsxXFNuo1c6N7hqgbn_KFzL9_ztPm1HC4/edit?usp=sharing
Provenance/Workflow dataset: http://search.test.dataone.org/#view/urn:uuid:bf71c38b-22b2-469e-8983-734ec0ab19cb
KNB: https://knb.ecoinformatics.org/#data/page/0
Download Morpho: https://knb.ecoinformatics.org/#tools/morpho
R DataONE library: https://releases.dataone.org/online/dataone_r/

We have a great tech roundtable on May 27!

Lauren Walker, a programmer based at NCEAS, will be leading an informal demonstration of the KNB: Knowledge Network for Biocomplexity, an international data repository and DataONE member node. She will demonstrate how to submit a dataset to the KNB via an online tool and through the DataONE R client.

She will also give a demonstration of the DataONE online search interface, which queries all 24 DataONE member nodes, using the same web software as KNB. This will include a preview of the upcoming scientific data provenance features in DataONE.

Lauren will open the roundtable up for feedback, suggestions, and to hear what you would find most useful with these kinds of tools.



Green infrastructure on the ground: The politics of aquifer replenishment in Los Angeles

Sayd Randle, Doctoral Candidate in Environmental Anthropology from Yale University, will be presenting the roundtable for May 20th, 2015. Come learn about green infrastructure contributions to groundwater, an increasingly important issue in our drought-stricken state.

Abstract: The City of Los Angeles imports roughly 90% of its potable water supply from beyond city borders, and relies on local groundwater for the remainder. Environmentalists have long advocated for increased groundwater augmentation through rainwater capture and infiltration around the city homes, streets, and parks the sit above the basins. Recent drought conditions and surface water adjudications have turned policymakers’ attention to these techniques for producing an increased, “more secure,” in-city water supply. This paper uses a political ecology framework to examine the politics of reconfiguring quotidian city spaces to restock groundwater stores, drawing on fieldwork among city bureaucrats, environmentalists, and homeowners undertaking retrofits.

Parkway basin


A Framework to Improve Data Attribution and Acknowledgement?

As scientific projects grow more collaborative, data citation and data attribution has emerged as challenging issue. Sophie Hou will be presenting her poster on this topic and leading a discussion on how scientists might look to the movies to improve data attribution and acknowledgements.

See Sophie’s Presentation

Abstract: As scientific data volumes, format types, and sources increase rapidly with the invention and improvement of scientific capabilities, the resulting datasets are becoming more complex to manage as well.  One of the significant management challenges is pulling apart the individual contributions of specific people and organizations within large, complex projects.  This is important for two aspects: 1) assigning responsibility and accountability for scientific work, and 2) giving professional credit to individuals (e.g. hiring, promotion, and tenure) who work within such large projects.

This presentation will provide an overview for the concept of data citation, its current practices, and the strengths and weaknesses of the current data citation methods when applied to climate model dataset.  Using the NCAR Global Climate Four-Dimensional Data Assimilation (CFDDA) Hourly 40km Reanalysis as a case study, the presentation will also demonstrate the creation and the result of a detailed data attribution.  Analogous to acknowledging the different roles and responsibilities shown in movie credits, the methodology developed in the study could be used in general to identify and map out the relationships among the organizations and individuals who had contributed to a dataset.  Finally, discussion questions will be presented in order to consider how this framework could be applied to create data attribution for other dataset types beyond climate models datasets.

Sophie with her poster

Sophie with her poster

Environmental Literacy for the Next Generation: Integrating science, pedagogy and communication

Carol Blanchette, Associate Research Biologist from the Marine Science Institute will be our Roundtable speaker next week. Please join us for a lively discussion on an interesting topic!


Abstract: “If science is going to fully serve its societal mission in the future, we need to both encourage and equip the next generation of scientists to effectively engage with the broader society in which we work and live” (Leshner 2007, AAAS CEO). This sentiment has been broadly embraced by scientists and non-scientists in recent years, along with the idea that scientists have a responsibility to share the meaning and implications of their work, and that an engaged public encourages sound public decision-making. Effective communication of science has become critically important in the environmental sciences, where public understanding of key environmental issues ranging from climate change to sustainable resource management has important policy implications.  In this roundtable I will provide a brief overview of some of my experience and activities in the realm of science education and communication, and I will provide an overview of OCTOS, a new hub for environmental communication and science education activities on the UCSB campus. I will lead a discussion focused on how we (as scientists) can help to build communication capacity, serve as resources for science educators, and how to evaluate the efficacy of these efforts.

Research in the coastal temperate rainforest, by Dr. Allison Bidlack

Juvenile Bald Eagle in Tree near Haines

Juvenile Bald Eagle in Tree near Haines

Join us for our March 11th Roundtable with Dr. Allison Bidlack from the Alaska Coastal Rainforest Center!

The north Pacific coastal temperate rainforest (PCTR) ecosystem extends from central British Columbia to southcentral Alaska, includes the largest remaining old-growth forests in North America, supports some of the most robust fisheries on the continent, and is home to tens of thousands of people who depend on a resource and tourism-based economy for their livelihoods. It is also a region characterized by an intricate geologic and evolutionary past, a rich cultural history, and complex linkages among ecosystem components. The social-ecological systems of the PCTR are being transformed by climate change, as well as by global economic drivers such as tourism, energy prices, and timber demand.  Given the current rates of ecosystem change and the potential for profound systemic shifts and economic upheaval in the region and beyond, a more holistic understanding of these patterns, processes and impacts is essential for the effective management of resources and the resilience of communities. This talk will provide a brief introduction to the region and some of the integrative work being performed, with an emphasis on regional projects involving existing datasets.


From the top of the mountain to the top of the world: vegetation change in the tundra

Join us for our roundtable discussion on March 4th with Dr. Anne Bjorkman from he German Center for Integrative Biodiversity Research (iDiv).

Abstract: Identifying large-scale patterns in functional traits has become a hot topic in community ecology over the past decade, as understanding current biogeographical patterns can help us predict future shifts under climate warming. In the Arctic, where temperatures are warming faster than anywhere else on the planet, shifts in vegetation and associated functional traits can have direct consequences for ecosystem function. For example, increases in shrub cover could affect summer and winter soil temperatures and thus influence the depth of permafrost thaw, while specific leaf area (SLA) and leaf nitrogen concentration can influence decomposition rates, relative growth rates, photosynthetic rates, and carbon fixation, all of which in turn influence carbon cycling and net primary productivity (NPP).

As part of an international synthesis effort based at the German Centre for Integrative Biodiversity Research (“iDiv” – the German equivalent of NCEAS, or at least we like to think so), we are investigating patterns of functional traits across climate space and over time by combining a circumpolar vegetation database with a large and growing tundra plant trait database. This is very much a work in progress, so I will present some of our work so far and would love to have your feedback!

Anne at her study site

Anne at her study site