Evidence from the past several decades shows that species distributions are shifting in response to climate change. However, even the most robust studies attribute less than half of observed changes in species distributions to local climate factors. Foundational ecology considers climate as just one of many drivers that determine species distributions. I will review five prevalent mechanisms that may explain some of the high variance around the relationship between species range shifts and climate velocity, and describe how they might affect a species’ climate tracking: (1) biogeographic boundaries, (2) habitat gaps and fragmentation, (3) biotic interactions such as competition, predation, and mutualism, (4) other abiotic constraints including light and trace elements, and (5) life history traits that determine dispersal capacity. This work supports conservation initiatives for threatened species by highlighting several processes that may limit their potential redistribution, and can inform analyses of observational data and species distribution models that seek to incorporate multiple processes rather than climate alone.
Alexa is a third-year PhD student at the Bren School of Environmental Science & Management at UCSB. Her research focuses on biogeographic processes that may prevent species from tracking climate change, particularly in the oceans. She has also studied human impacts to coastal marine ecosystems, and participated in the Ridges to Reef Fisheries SNAPP Working Group. Before entering graduate school, she worked for the Environmental Defense Fund on management of the West Coast groundfish fishery, and graduated from Princeton University in 2012 with a B.A. in Ecology and Evolutionary Biology.
Global change will alter resources, which are predicted to change the composition and functioning of plant communities. Here, I present the results of several projects studying plant community changes in response to resource manipulations. First, I present data from an experiment at Konza Prairie Biological Station in Manhattan Kansas. In this experiment, nutrient additions (nitrogen and phosphorus) turned the tallgrass prairie from being dominate by C4 grasses to C3 forbs. Next, I detail plant community responses to resource manipulations across ~100 experiments world-wide. This data synthesis found that when 5 factors are simultaneously manipulated, there are drastic changes in the plant community. Additionally, the greater number of factors that are manipulated, the greater the change in productivity. Lastly, I review my current postdoctoral work, focused on developing new ways to study patterns of community change using rank abundance curves.
Photo of the phosphorus plots experiment at Konza Prairie Biological Station. Photo Credit: Melinda Smith
Climate change is expected to profoundly impact terrestrial vegetation, and the mechanisms, rate and extent of change will influence biodiversity conservation and the ecological functions of natural ecosystems. The San Francisco Bay Area has steep climate gradients and rugged topography, supporting a wide range of natural habitats. Using a novel application of multinomial logistic regression, we have modeled the projected impacts of climate change on Bay Area vegetation. Model projections are evaluated over a wide range of possible future climates, allowing us to evaluate sensitivity of vegetation to changing climate, without choosing specific future climate scenarios. Sensitivity is highly variable across the Bay Area. Perhaps surprisingly, sensitivity to climate change is modeled to be greater on north-facing slopes and cooler locations. The model projections are best interpreted as the long-term equilibrium response to a particular degree of climate change, but they do not provide insight into how fast this equilibrium will be achieved or the transient states that may occur in response to rapid climate change. We combine model results with a discussion of the ecological mechanisms of vegetation change to better understand the challenges raised by disequilibrium dynamics and the implications for conservation biology in coming decades.
Dr. David D. Ackerly
Department of Integrative Biology
University of California, Berkeley
In this round-table, I will discuss how global change are transforming small-scale, native, resource-dependent communities in the Arctic. These social-ecological systems are increasingly exposed to global warming, industrial development and globalization, which subsequently alter the local SES dynamics. Subsistence use of fish and wildlife is a cornerstone in these communities. This traditional utilization of natural resources are commonly assumed to be donor-controlled, in which the users do not control the resource level but adapt to the fluctuating availability of fish and wildlife. A combination of increased harvest efficiency through the introduction of new technology, increased resource demand through population increase and commercialization, and reduced resource stocks by exogenous pressures such as climate change, is likely to increase the pressure on the stocks of fish and wildlife. The result could be a transition of the SES from a provisioning action situation, where the collective challenge is to secure subsistence on a local scale, to an appropriation action situation where the collective challenge is to avoid overuse of a common-pool resource on the scale of the resource stock. We applied cross-national comparison of Arctic Alaska, Canada and Greenland, synthesized secondary data from documents, official statistics and grey and scientific literature, and asked: What are the evidence for SES transitions in the Arctic? Which exogenous pressures are associated with transitions, and what conditions might prevent transitions? How does the transitions change the focus and sustainability challenges faced by the governance systems?
Although the results I will present are from the Arctic, I hope the talk will stimulate a more general discussion on how global change might transform local social-ecological systems.
Dr Per Fauchald
NCEAS visiting scientist
Senior researcher at the Norwegian Institute for Nature Research
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.
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.
Next month, the global science community will come together ahead of the COP21 of the UNFCCC in December to discuss the key issues concerning climate change. Discussion will include a focus on the ocean. The ocean is critical to life on Earth through its regulation of atmospheric gases, stabilisation of planetary heat, and provision of food and resources to well over 4 billion people worldwide. I will start with a peek at the processes for the Fifth Assessment Report (AR5) of the IPCC, including the roles of the authors, editors and expert reviewers, coordination across chapters and working groups and assessment of the literature. AR5 included a number of oceans chapters for the first time, which identified serious risks to marine ecosystems, fisheries, and coastal livelihoods. Focusing on these, I’ll discuss the key findings, updating with recent knowledge, with particular reference to the 2°C global warming target.
CSIRO Oceans and Atmosphere Flagship, Brisbane, Australia
Global Change Institute, University of Queensland, Brisbane, Australia
CSIRO Hobart – – photo by Bruce Miller 4/2008
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