Wageningen University & Research | WEC

Problem description

Understanding the drivers of the productivity of forests at large scale is important, for example to assess their capacity for carbon sequestration, and their potential for production of biomass and timber. In the Netherlands, forest growth is monitored in the Dutch National Forest Inventory (see here).

Forest productivity (forest growth) may vary with forest stand age (younger forests may be more productive; Bose et al. 2014), tree species composition (fast vs. slow-growing species), and tree species diversity (Liang et al. 2016, Lu et al. 2018). Spatial variation in forest productivity will likely also be closely linked to variation in soil characteristics and forest management. Forest management, for example, influences tree density, which in turn influences light availability to trees.

In addition to local management effects, and large-scale background in soil characteristics, environmental change may also affect forest productivity. In the Netherlands, for example, levels of nitrogen deposition are generally high, but levels do vary across the Netherlands, and may have an effect on forest productivity.

Challenge

You will assess what drives forest growth in the Netherlands, unravel and visualize patterns, and generate understanding on ecological patterns and interactions. Many questions can be explored. Does forest growth vary with soil characteristics? Is productivity higher in more diverse forests? Does forest growth vary with the dominant species? Does nitrogen deposition influence productivity?

Available data

Different datasets will be supplied that have to be creatively merged and processed:

  • The Dutch Forest Inventory dataset will be used:
    • Tree diameter data for ~3600 forest plots in the first census (~2001-2005), for ~1200 plots diameter data for the second census (2012-2013) are available as well. Trees have been identified to species. Metadata for plots is available: the approximate location, stand age, and whether forests are planted or not. These data will be provided in .csv files (in English).
    • The full dataset is available online, including detailed information on the methods, if you want to include additional variables (the file is in MS Access format; and in Dutch): see here
  • GIS layers of soil variables.
  • GIS layers of nitrogen deposition.

References

Bose, A. K., M. J. Schelhaas, M. J. Mazerolle, and F. Bongers. 2014. Temperate forest development during secondary succession: effects of soil, dominant species and management. European Journal of Forest Research, 133: 511-523.

Liang, J. J., et al. 2016. Positive biodiversity-productivity relationship predominant in global forests. Science 354.

Lu, H. C., S. Condes, M. del Rio, V. Goudiaby, J. den Ouden, G. M. J. Mohren, M. J. Schelhaas, R. de Waal, and F. J. Sterck. 2018. Species and soil effects on overyielding of tree species mixtures in the Netherlands. Forest Ecology and Management 409: 105-118