US-1: Holocene fire history in the Klamath region
Title: Ecosystem response to climate change in northwestern California over the last 4000 years
Investigators: Whitlock, Briles
Students: White (MS MSU)
Opportunities for intern participation: possible opportunity for Native American intern participation in fieldwork.
The vegetation and environment of northwestern California (NWCA) shares many similarities with Tasmania and New Zealand, including (1) its location in a winter-wet/summer-dry temperate climate; (2) a complex fire regime and history including recent severe stand-replacing fires; (3) extraordinary floristic biodiversity and endemism resulting from complex geology and steep topographic gradients; and (4) a striking coastal-to-inland precipitation gradient. Under future climate-change scenarios, diverse ecosystems in NWCA are projected to experience shifts in plant distributions, including a loss of high-elevation species, an expansion of low-elevation woodland trees, and increased fires and insect outbreaks. How such range shifts will take place and what will be the role of natural disturbance in facilitating ecological reorganization are topics of considerable discussion and concern within the scientific and forest management communities. Our research draws on previous work in NWCA focused on Holocene fire, vegetation, and climate history (Briles et al., 2005, 2008, in press; Whitlock et al., 2008). The goals of this joint PIRE/Forest Service project are to gain a better understanding of vegetation-fire-climate dynamics over the last 4 kyr, and evaluate the influence of geology and climate gradients on disturbance and vegetation patterns. We are interested in the late-Holocene history of Tsuga mertensiana at high-elevations and Pseudotsuga menziesii at low elevations in the Klamath-Siskiyou region. Previous studies suggest that these ecologically and economically important conifers display particular sensitivity to past climate changes and their southern limit in NWCA today may be highly vulnerable to future climate change. Long ecological records provided by pollen, charcoal, and other biological proxies preserved in the sediments of cirque and landslide-dammed lakes offer an opportunity to examine the forest dynamics during periods of known climate change (e.g., Medieval Climate Anomaly and Little Ice Age), including the role of fire.
Work plan: A network of late-Holocene records will be developed using the findings from previous students and results from 6-8 new records from the southern Cascades and northern Sierra Nevada where data are limited. Pollen, charcoal, and lithologic data will be examined to determine the influence of climate and local conditions in shaping vegetation composition and disturbance regimes. We will evaluate historical range shifts of Tsuga and Pseudotsuga along climate gradients and on different substrates. The study will also provide high-resolution fire-history reconstructions that will be compared with those from Tasmania and New Zealand (PIRE NZ-1, PIRE TAS-1, PIRE TAS-4).
Related Activities – Associated Funding
A Cooperative Agreement ($144K for 3 years) between the USDA Forest Service and Montana State University currently supports the project. The agreement covers the cost of Klamath fieldwork, graduate student stipend, travel for Briles, and logistical and analytical expenses. Ali White, a MS student in Earth Sciences at MSU, will work on the project and spend time in Monash University collaborating with Briles. Undergraduates from MSU and Honor students at Monash University will be involved in fieldwork, data collection, and analysis and interpretation of the data, with non-PIRE funds.
We are also collaborating with the USGS scientists (Scott Starratt, Elmira Wan, and Dave Wahl) on some of these sites, drawing on their interest in the limnobiotic history and tephrochronology of northern California.
The proposed study will result in manuscripts on (1) the regional vegetation and fire history of NWCA and its comparison with existing records in the Pacific Northwest; (2) multiple scale controls (i.e., geology, climate, fire and site location) on forest dynamics; (3) historic range expansions and contractions of two important plant species and the possible role of fire in facilitating these adjustments; and (4) the historical range of natural variability for plant communities vulnerable to climate change. The study will help describe the role of fire, geology and climate in maintaining forest composition and structure in biologically diverse regions.
Year 2 Update
The objective of this project is to provide a temperate rainforest comparison for the research underway in Tasmania and New Zealand. The Klamath region supports a diverse vegetation, steep elevation gradients, and considerable spatial heterogeneity in fire patterns. Anthropogenic fires in this region may have occurred throughout the Holocene, although burning was most intense in the last 3000 years and especially after European settlement. The primary support for this project comes from a Cooperative Agreement with the USDA Forest Service Pacific Southwest Research Station. PIRE provides the opportunity to compare the results from the Klamath region with Holocene records from temperate rain forests in Australia and New Zealand. PIRE also has allowed for research exchanges with Dr. Christy Briles, a Lecturer at Monash University and former postdoctoral research associate at MSU. The Cooperative Agreement supports the research of MSU MS student Ali White, who will have the opportunity for overseas work in Year 3. Scientists from the U.S. Geological Survey are also collaborating on the Klamath project.
In year 2, extensive field work was undertaken to collect sediment cores for charcoal and pollen analysis. Cores were taken from Upper Twin Lake, Black Rock Lake, Diamond Lake, Hobart Lake, Kelly Lake and Miller Lake in the Klamath region. These cores have been described lithologically and subsampled for pollen, charcoal, magnetic susceptibility, and radiocarbon dating. Paleoecological analyses are currently underway at the MSU Paleoecology Laboratory and Monash University.