Estimating historic N- and S-deposition with publicly available data – An example from Central Germany

The deposition of reactive nitrogen and sulphur has profound effects on ecosystem functioning. In the last decades, monitoring networks providing high resolution spatio-temporal deposition estimates have been set up, but equivalent information on historic deposition is mostly missing. However, understanding vegetation change and mitigate future loss of biodiversity and ecosystem functioning is only possible evaluating the effects of its strongest drivers, which includes deposition in many ecosystems. Here, we combine different data sources to provide estimates of historic deposition in forested ecosystems on a high spatio-temporal scale for a federal state in Central Germany from 1880 to present.

We make use of data from field measurement stations together with elevation and precipitation data from the last three decades to build a simple deposition model, validate this model with a model publicly available covering the time range from 2000 to present, and extrapolate deposition from this joint model to the past using European deposition trends from the last 150 years.

Our approach can easily be adapted to other data and spatial areas shows how to use raw deposition data together with publicly available data on elevation and precipitation to construct simple deposition models covering recent and historic times in areas and for times for which no data are available.

Methods
Data on European emission and deposition trends was collected from several studies mentioned in the original publication using the digitize R-package which allows for the conversion of graphical data to numeric values.

The FFK data were received and uploaded with the permission of the Forstliches Forschungs- und Kompetenzzentrum (FFK Gotha), a department of the Thuringia forestry department.

The UBA data are publicly available upon request from the Umweltbundesamt, the federal Environmental Agency from Germany.

Rainfall data were retrieved from Climatology Lab (http://www.climatologylab.org/terraclimate.html) and CRU.

Elevation data was retrieved from ASTER GDEM, a product of METI and NASA.