Holocene temperature estimates and chironomid community composition in the Abisko Valley, northern Sweden

Abstract

Multi-proxy paleoenvironmental reconstructions are useful to determine the various factors affecting the biological communities of a lake, but to assess if changes in community composition of one indicator organism accurately reconstructs climatic changes through time, it may be more useful to compare temperature reconstructions using the same indicator in several lakes. Here, we compare reconstructions of mean July air temperature using chironomid-based transfer functions from Holocene records at three nearby lakes in the Abisko Valley of northern Sweden to assess if chironomids can be used as indicators of regional temperature changes. The three study lakes experience the same regional climatic conditions, but are located along gradients of elevation (348–999 m a.s.l), temperature (8.1–12°C) and terrestrial vegetation (coniferous to alpine). Chironomid-temperature reconstructions from the three sites indicate a general pattern of temperature decrease (1.5–2.4°C) during the Holocene, consistent with decreases observed from analyses of other proxies in this area, and from other alpine regions in Europe and North America. Similarities between these reconstructions suggest that chironomids can adequately record general patterns of temperature changes through the Holocene, although effects of site-specific factors such as variations in lake water pH can cause deviations in inferred temperature among sites during some periods.