Palynologists study fossil pollen, which was produced by former plants and deposited in lake/marsh sediments. Pollen grains vary according to their outer coat (exine).
The main characteristics of alder pollen are arc-shaped structures connecting pores. Oak pollen has striate surface and three furrows, whereas pine has two reticulate air bladders to float in the air more easily.
Pollen is quickly destroyed by aerobic bacteria, but in suitable environments (e.g. in anoxic conditions of lake and marsh sediments) it can survive for thousands, even million years. Palynologists collect samples of lake and marsh sediments by coring or we take stratigraphic columns from profiles of archaeological trenches and store them in cold place. In palynological laboratory these samples are chemically treated to extract pollen and analysed using light microscopy at 400x magnification.
The results of palynological research can help us to reconstruct changes of vegetation, which were triggered by climatic fluctuations and human impact on the environment. For more information about my research see: RESEARCH, REFERENCES and web site of Institute of Archaeology ZRC SAZU, where I work. Recently my colleagues and I also published a manual: Andrič M., Tolar T. in Toškan B. 2016. Okoljska arheologija in paleoekologija: palinologija, arheobotanika in arheozoologija. Ljubljana, Založba ZRC. (Environmental Archaeology and Palaeoecology: Palynology, Archaeobotany and Archaeozoology, in Slovenian).