Collaborative Research: Nutritional Landscapes of Arctic Caribou: Observations, Experiments, and Models Provide Process-Level Understanding of Forage Traits and Trajectories

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Terrestrial Arctic systems are the result of complex interactions between climate, vegetation, herbivores, and humans that must be studied together to understand their functional
traits. While low temperatures and short-growing seasons limit plant growth, enough plant biomass exists to support herds of migratory caribou, on which Alaska Natives depend. Any changes in the plants at the base of the food web can have cascading consequences for herbivores and human consumers and their interactions. Today, the Arctic system is in the midst of change resulting in new vegetation assemblages, changes in the nutritive value of plant tissues, and ultimately in the diets of migratory caribou and the humans that depend on them. This project examines the nutritional landscape of the Central Arctic Caribou Herd as a unifying concept, describing the nutritional landscape as caribou available protein (CAP) and caribou available energy
(CAE), integrative forage quantity measures that reflect biomass, species composition, plant
C and N content, digestibility, and secondary compounds. The core objectives are gaining understanding of the drivers of spatial and temporal patterns in the amounts of CAP and CAE across the tundra; caribou use of this nutritional landscape; how the amounts of CAP and CAE will differ in the future under likely climate scenarios and long-term experiments, and the interactions between caribou and Native communities. The broader impacts of this study involve several groups of Alaskan stakeholders, including: harvesters of the North Slope community of Nuiqsut, the worldwide caribou community, and students at multiple stages of education. The project will embed a team member with hunters in Nuiqsut,
and develop an educational scientific documentary on the caribou - Alaska Native interactions for
high school students. The group plans to employ village students and undergraduates affiliated with the Alaska Native Science
and Engineering Program to assist with experimental work and vegetation collection at Toolik Lake. This research is significant to ecologists from the Circumarctic Rangifer Monitoring
and Assessment Network, dedicated
to caribou conservation and sustainable management in the US, Canada, and Scandinavia, who will use the data to consider how a suite of climate change scenarios affect herd fecundity and population dynamics. The intellectual merit of this project stems from the merging of five elements to understand Arctic
System function and response to climate change: (1) A landscape-scale assessment of plant species, soil and plant C and N, digestibility, and secondary compounds that will be used
to calculate the amounts of CAP (kg m-2) and CAE (kJ m-2); (2) analysis of how closely caribou foraging is tied to the nutritional landscape throughout the year; (3) analysis of samples
from an existing long-term winter - summer climate change experiment to provide data on how
CAP and CAE will differ in the future; (4) prediction of future nutritional landscapes and
caribou foraging interactions; and (5) observations of Alaska Native hunter harvesting and attributes
of the system that determine their spatial and temporal patterns. These project components will enable an integrative understanding of how an important herbivore, caribou, interact with a landscape that is rapidly changing. This research: (1) examines the Arctic System from primary production to secondary consumers and the
influence of climate change across multiple trophic levels; (2) applies broadly by examining
the most abundant large herbivore and its food sources, both of which are distributed throughout
the Arctic; and (3) integrates experimental, observational, and modeling approaches to understanding ecological systems and climate change. The integration of observation, experimental data
and modeling to describe current and forecast future nutritional landscapes is intended to provide a
mechanistic understanding of Arctic System function and transform the understanding
of climate-vegetation-caribou-subsistence hunter interactions.