Improved reconstruction of palaeo-environments through unravelling of preserved vegetation biomarker patterns

Montane forest composition and specifically the position of the upper forest line (UFL) is very sensitive to climate change and human interference. As a consequence, reconstructions of past altitudinal UFL dynamics and forest species composition are crucial instruments to infer past climate change and assess the impact of (pre)historic human settlement. One of the most detailed methods available to date to reconstruct past vegetation dynamics is the analysis of fossil pollen. Unfortunately, fossil pollen analysis does not distinguish beyond family or generic level in most cases, while its spatial resolution is limited amongst others by wind-blown dispersal of pollen, affecting the accuracy of pollen-based reconstructions of UFL positions. To overcome these limitations, we developed a new method based on the analysis of plant-specific groups of biomarkers preserved in suitable archives, such as peat deposits, that are unravelled into the plant species of origin by the newly developed VERHIB model. Here we present this new method of biomarker analysis and describe its first application in a peat sequence from a biodiversity hotspot of montane rainforest in the Ecuadorian Andes. We show how a combination of the new biomarker application with conventional pollen analysis from the same peat sequence yields a reconstruction of past forest compositions, including UFL dynamics, with previously unattainable detail.