Abstract One goal of pollen analysis is to document the arrival of a plant taxon to an area. In the region of treeline, the arrival or disappearance of spruce is of interest for paleoecological or paleoclimatic reconstructions. However, pollen are transported by several mechanisms, including by wind, streams and insects, and some pollen are transported far from the source plant. Although pollen can be used to document the presence of a taxon on regional scales, at a site level it is sometimes difficult to determine the arrival of a species in the immediate area of a lake from the fossil pollen. The arrival of spruce in the watershed should be recorded in the lake sediment chemistry.
Conifer species tend to acidify the soil.
The acidification of the soil should influence the water in streams and lakes, thus influencing mobility of some elements in the lake water column. Thus, the presence of spruce should be recorded in lake-sediment chemistry. This study was conducted in the area of the Rivi re Boniface in northern Qu bec. Lake-sediment cores were raised from two sites 15 km apart. The region surrounding site RB6 is currently forested, whereas lake RB23 is near the tree limit.