Uncertainties in plant functional type (PFT) products for use in regional climate models - assessing the sensitivity of global PFT time series to different input data and cross-walking procedures.

Abstract:

The concept of plant functional types (PFTs) is shown to be advantageous in representing the floristic complexity of plant characteristics in land use and climate change studies using regional climate models (RCMs). By representing land use and land cover (LULC) as functional traits, responses and effects of specific plant communities can be directly coupled to the atmospheric layers. However, the translation of existing land use and land cover (LULC) products into PFTs implicates uncertainties in the final products that need to be assessed.

The present work gives a detailed description of the translation of the annual global land cover maps from ESAs Climate Change Initiative (ESA CCI LC) into 16 PFTs that are tailored to the needs of high resolution RCMs. The translation is refined by using the Holdridge life zone system, consisting of 30 ecosystem types to take regional differences of the PFTs into account.

In order to assess the uncertainty of the final PFT product and the sensitivity to different input data and cross-walking procedures, the global PFT maps are compared to other global PFT products regarding global land cover change trends. Based on the comparison results we strongly recommend the comprehensive documentation of all modification and translation processes that are applied to LULC datasets when used in regional climate models.