Assessing and Harmonizing Lying Deadwood Volume with Regional Forest Inventory Data in Wallonia (Southern Region of Belgium)

Abstract

Using lying deadwood or coarse woody debris (CWD) as an indicator of biodiversity and of sustainable forest management is on the rise among national and local forest inventories. Nevertheless choosing the most suitable sampling method is difficult as it depends mostly on CWD abundance and dimensions. In addition the CWD volume estimates of different regional inventories are rarely comparable. We therefore tested two generally recommended methods for lying deadwood: line intersect sampling and fixed area sampling. We assessed both methods in plots of the regional forest inventory of Wallonia (southern region of Belgium). Next we developed bridging functions that converts CWD volume estimates to estimates that would have been obtained with different thresholds. Results about precision and time requirement are very slightly in favour of the line intersect sampling method. Nevertheless, we have noted that this method has several drawbacks, especially in the context of a regional and multi-resource inventory. Beside the established bridging functions indicate that CWD volume estimate from the Walloon forest inventories should be reduced by 20% in order to be internationally harmonized.