Bonanza Creek LTER

Disturbance, Resilience, and Ecological Memory in the Boreal Forest

Climate change impacts Earth's ecosystems by disrupting established ecological communities and initiating processes of recovery. Although history provides many examples of communities and ecosystems recovering from disruption, changes in climate and human activities are shifting the scale, patterns, and forms of disturbance, often with important consequences for humanity. Changes to vegetation, permafrost, hydrology, species distribution, and landscape are already occurring at unprecedented rates in the boreal forest. Average surface air temperature, for example, is increasing at around twice the global average in boreal forests of Interior Alaska.

Understanding these boreal changes -- when, where, and how shifting climate and changing disturbance fundamentally are altering the dynamics of the Alaskan boreal forest -- is the central focus of the Bonanza Creek LTER. Close study of past events is an essential component of this effort; by improving our understanding of ecological legacies [glossary: pop-up] and their interactions with disturbance, we can better predict when and where boreal ecosystems will be most vulnerable to contemporary and future changes in climate and disturbance.

Study Design

Integrating Legacies Across Time and Space

Long-term monitoring of climate, disturbance, ecosystem attributes, and social-ecological systems allows us to document change across seasons, years, and decades. Chronosequence [pop-up definition], dendroecological [pop-up definition], and paleoecological [pop-up definition] studies provide historical context for climate–disturbance interactions spanning centuries to millennia. Our modeling efforts look both back to this history and to the future, predicting the consequences of current and future landscape patterns at spatial scales ranging from individual plants to whole ecosystems and the broader boreal biome. Terrestrial ecosystem models couple vegetation, biogeochemical cycles, and biophysical processes to estimate disturbance and climate impacts on ecosystem distributions, carbon balance, and feedbacks to high-latitude regions and the Earth system.

Core Landscapes of Interior Alaska

Our study design includes the key landscape types found in Interior Alaska—uplands, floodplains, forest–tundra, and wetlands and peatlands. For its first 30 years, Bonanza Creek LTER research was concentrated near Fairbanks in the Bonanza Creek Experimental Forest and the Caribou–Poker Creeks Research Watershed. Long-term monitoring of successional sequences, streamflow, chemistry, and fire effects has been ongoing at some locations since the 1970s. During the past two decades we added additional long-term experiments at Eight Mile Lake, the Alaska Peatland Experiment, the Delta Experimental Fertilization Treatment, and other sites.

Regional Site Network (RSN)

To study climate–disturbance interactions across the boreal landscape, Bonanza Creek LTER has established a network of 94 long-term study sites, known as the Regional Site Network. We selected these sites to represent young (<20 years), intermediate (40–60 years), and mature (>60 years) stages of post-fire development, with an initial emphasis on black spruce–dominated stands. We are expanding the Regional Site Network to include mature deciduous stands, allowing us to study a broader range of forest succession pathways over approximately 100 years of post-fire ecosystem development.

New Dimensions of Landscape-Scale Monitoring

Our landscape-scale monitoring includes two new dimensions. First, we recently began annual monitoring of newly burned black spruce stands to examine how variations in post-fire climate conditions influence how the boreal forest is responding to disturbances. Second, we have expanded our research into abrupt permafrost thaw at lowland sites in the Tanana River and Minto Flats regions as well as at upland sites in Denali National Park and Preserve.

Working Groups

Working groups focused on wildfire, consumer outbreaks, and permafrost thaw and ecohydrology drive Bonanza Creek LTER’s primary research. These themes are supported by ecosystem modeling and social-ecological working groups that project the types and impacts of changes to the boreal forest biome. Another working group focuses on knowledge-sharing efforts, which engage K–12 students, undergraduate researchers, and the broader public through educational programs, social media, publications, exhibits, and performances. We are also expanding our efforts to strengthen connections among partners and Bonanza Creek LTER scientists through artist–scientist collaborations, science internships for youth, and the guidance of our new Alaska Native Advisory Council.