Climate Cascade: Linking Temperature, Phytochemistry and Vertebrate Demographics

EPA Grant Number: F13B20220
Title: Climate Cascade: Linking Temperature, Phytochemistry and Vertebrate Demographics
Investigators: Berini, John Lawrence
Institution: University of Minnesota
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: September 2, 2014 through September 2, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Terrestrial Ecology

Objective:

Moose are an important ecological component of the boreal ecosystem, are notoriously heat intolerant and are at the southern edge of their circumpolar distribution in northern Minnesota. Although the relationship between increasing temperatures and the decline of moose in Minnesota is well documented, it is critical to identify the precise mechanisms underlying this relationship in order to understand how large herbivores will respond to continued warming. This study investigates the potential impact of climate change on moose at the southern edge of their bioclimatic envelope by addressing the following questions: How do increasing temperatures affect forage quality? How do increasing temperatures affect forage selection by moose? How does habitat quality affect the demographics of the moose population?

Approach:

Plant samples will be collected from a controlled warming experiment, in which 10 different tree species important to the boreal ecosystem have been grown since 2008 under three different temperature regimes: ambient, ambient +2 °C and ambient +4 °C. These samples will be analyzed to determine how the number and concentration of different plant secondary metabolites vary as a function of temperature. Similar analyses will be conducted on forage samples collected from more than 60 semipermanent plots located throughout northeastern Minnesota—a region that spans a 5 °C summer temperature gradient and includes multiple disturbance types (e.g., clear cuts, burns, etc.) and ages. Changes in ambient temperature also will be recorded at each plot at 2-hour intervals throughout the duration of the study. Forage and moose tissue samples will be analyzed for stable isotopes of carbon and nitrogen, and these data will be used to estimate diet composition with a series of Bayesian mixing models. Moose tissue samples have already been collected from more than 150 radio-collared animals as part of a parallel study being conducted by the Minnesota Department of Natural Resources (MNDNR). Finally, the annual aerial survey data collected by the MNDNR will be used to estimate changes in spatially explicit demographic rates and population growth rates as a function of different temperature regions, disturbance types, disturbance ages and forage quality. Finally, general linear models will be used to investigate the effects of temperature, disturbance type and age and forage quality on population vital rates and to determine if any one variable is overwhelmingly responsible for the decline of moose in Minnesota.

Expected Results:

There is an urgent need for a mechanistic understanding of how animals interact with changing landscapes. Using the declining Minnesota moose population as a case study, this research addresses that need by synthesizing multiple sources of spatiotemporal data to provide landscape-scale, spatially explicit predictions of habitat use and demographic change. By investigating the chemical response of numerous tree species that play a critical role in the structure and function of the boreal ecosystem, this study investigates how the physicochemical landscape may be altered by present and future climate change. The demographic data provide unique insights into how a keystone herbivore may be altering its habitat-use behavior as a result of these changes and how these behavioral changes may, in turn, be affecting landscape-scale population growth.

Potential to Further Environmental/Human Health Protection

While this research directly addresses questions of management concern, it also advances the understanding of how climate change affects animal populations by investigating how increased temperatures are affecting forage quality, how animals mitigate environmental stress, and how behavior and landscape context affect diet and, consequently, population demographics. The transformative power of this project is that it will link the diet and habitat use of individuals to population demographics and the spatial and temporal variations in the biotic properties of the environment.

Supplemental Keywords:

climate change, foraging behavior, habitat use and loss