The long term fire history at the treeline in Northern Quebec can be evaluated by ecological surveys of the major ecosystems. Available data suggest that fires are presently climate-controlled, and therefore may be used as paleoclimatic indicators. During a cold climatic interval, postfire tree regeneration is hindered, and a shift from forest to barren conditions is recorded. Examples from specific environments are provided in order to reconstruct significant ecological periods of the fire history since 3,000 years B.P. (Before Present). A preliminary interpretation indicates that these periods of climatic cooling are centered around 2,800-2,500, 2,200-2,000, 1,600-1,400, 1,100-900, 700 ?, 500-100 years B.P.