Exploring the patterns and causes of land use changes in south-west Sweden

Abstract

To study the causes of agricultural declines in south-west Sweden, a multi-proxy study including pollen analysis, bog surface wetness indicators and aeolian sediment influx reconstructions was carried out on the Store Mosse Bog, situated on the coastal plain of Halland. Patterns of agricultural changes during the past 6,000 years from this study were compared to one additional site on the coastal plain (Undarsmosse Bog) and to four sites in the forested upland region. First, we compared land use activity on the coastal plain and in upland regions of south-west Sweden. Three periods with reduced agricultural activities were observed, primarily in records from the coastal plain. Next, the causes for these declines were studied by comparing land use indicators in the pollen records from the Store Mosse and Undarsmosse peat bogs to independent climatic reconstructions based on the same core material (past storm activity based on aeolian sediment influx onto the peat bogs; bog surface wetness reconstructed from organic bulk density measurements). Since the climatic reconstructions and pollen analysis were carried out on the same peat cores, a direct comparison between the timing of climatic events and land use changes was possible. Results indicate that climatic perturbations prior to ca. 1,000 years ago contributed to or possibly caused agricultural declines. The agricultural expansions near the Store Mosse and Undarsmosse bogs from 3000 to 2600 cal. yrs b.p. ended at the time when climatic proxy indicators recorded climatic instability (from ca 2600 to 2200 cal. yrs b.p.). The same sequence of events was recorded around 1500 cal. yrs b.p. and from 1200 to 1000 cal. yrs b.p., suggesting a climatic cause for these agricultural declines as well. The well-known climatic perturbations associated with the Little Ice Age, however, did not have a visible impact on agricultural activities. By this time, advances in land use knowledge and technology may have drastically diminished society’s sensitivity to climatic changes.