Spatial occurrence of drought-associated damages in Finnish boreal forests: results from forest condition monitoring and GIS analysis

• Published in: Boreal environment research 2015, Vol.20 (2), p.172
• Main Authors: Muukkonen, P, Nevalainen, S, Lindgren, M, Peltoniemi, M
• Format: Article
• Language: English
• ISSN: 1239-6095; 1797-2469

In boreal forests, some growing sites are more vulnerable to decreased soil moisture than others, which might result in stress symptoms in trees and thus affect their growth. We combined Finnish forest health data (ICP Level 1) with GIS data describing growing conditions, soil properties and soil water conditions to find out ways to identify the most vulnerable risk areas. The summer of 2006 was extremely dry, and the relative soil water index (SWI) in August relative to the 30-year average was only about 25%. This led to a higher percentage (24%) of sites (603 in total) where trees showed drought-damage symptoms. Our study shows that the risk of drought damages differs spatially depending on climatic conditions and soil properties. The most important variables to identify risk areas are the proportion of bare-rock areas, topographic wetness index (TWI), soil water indices (absolute and relative) and the spatial location on the north–south axis.