NZ-1: Holocene fire records

Title:  Holocene Fire Activity in the McKenzie Basin and Inland Otago, South Island, New Zealand

Investigators:  McWethy, Wilmshurst, McGlone

Students: Krause (MSU PhD)

Project Description

Objectives:  The assumption is made that fires prior to the arrival of Polynesians were very infrequent because the vegetation of New Zealand is ignition limited.  When people arrived, they provided the necessary ignition and their fires, in turn led to major shifts in the vegetation, including loss of 40% of the forests in the South Island.  Despite this assertion, the few charcoal studies from the region show low levels but persistent charcoal presence, and interior Otago region and McKenzie Basin, charcoal levels suggest recurrent, possibly ecologically significant fires.  New high-resolution approaches that examine macroscopic charcoal in contiguous intervals of sediment core have proven successful in identifying local fire occurrence as well as temporal trends in fire frequency and area burned (Higuera et al., 2010).  We propose to develop high-resolution fire reconstructions at a few sites where Holocene pollen records are available.  Our objectives are to (1) determine the importance of fire in fire-sensitive vegetation prior to human arrival; (2) identify whether area burned or fire frequency increased during periods of warming, such as the early Holocene (McGlone et al. 2010); and (3) provide new Holocene datasets that can be compared with records from similar settings in Tasmania, northern Patagonia, and the western U.S. (PIRE Syn-2).

Work Plan:  We will select one or two sites from the interior Otago region and McKenzie Basin for high-resolution charcoal analysis.  We may subsample existing cores with pollen data and radiocarbon chronologies, but we leave open the possibility of collecting new cores where needed.  The analysis will use modern procedures, and the charcoal data will be statistically decomposed into time series of fire episodes, fire frequency, and area burned estimates (Higuera et al., 2009).  This work will be undertaken by Teresa Krause, a PhD student from Montana State University, and the opportunity will provide her with important international research experience beyond her dissertation studies in the Greater Yellowstone.  It will require an undergraduate intern to help collect and analyze samples.

Related Activities

Research will supplement information from the charcoal-based fire studies of the last 1000 years (PIRE-2) and provide new information for McGlone, who has a long-standing research interest in New Zealand’s vegetation and climate history.

Expected Outcomes

One or two high-resolution Holocene charcoal records from southern South Island, in fire-sensitive regions.  The results will be published with Krause as lead author and the data will be used in other synthetic activities.

Year 2 Update

 

This project focuses on understanding the fire history of New Zealand during the last 11,000 years to determine if fires may have been more frequent during periods of dry climate.  A lake-sediment core from a New Zealand site (Boundary Stream) is under study for charcoal analysis to complement an existing pollen record.  The site is located in south-central South Island, New Zealand, and we expect that it would have experienced a greater frequency of naturally-ignited fires during the early Holocene due to climatic and edaphic conditions that were drier than at present. A charcoal record from this site will provide an important test of whether fire was rare to absent prior to Maori arrival.  MSU PhD student Teresa Krause spent several days working with Wilmhurst and McGlone at Landcare Research, Lincoln NZ.