Towards a more comprehensive and harmonised forest health monitoring: Application to three canopy defoliation in Spain

Abstract

Tree canopy defoliation is one of the best indicators to assess the phytosanitary status of forests. There are several networks in Spain that collect defoliation data: International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP-Forests), Regional Damage Monitoring Networks, and National Parks Monitoring and Evaluation Network.

The aim of this study is to analyze the dynamics of canopy defoliation in bioclimatic regions, stands and both conifers (Abies alba, Pinus uncinata, Pinus sylvestris, Pinus nigra, Pinus halepensis, Pinus pinaster and Pinus pinea) and hardwoods species (Castanea sativa, Fagus sylvatica, Quercus pyrenaica, Quercus robur, Quercus ilex, Quercus suber, Quercus faginea and Olea europaea) from mainland Spain and the Balearic Islands.

Different damage networks information was harmonised into an integrated network made up of 2858 plots with data between 1986 and 2015. The results show an increase in the average defoliation (12.3% in 1986 to 25.2% in 2015). In conifers species, P. uncinata (Alpine region), P. pinaster (Atlantic region) and P. halepensis (Mediterranean region), showed the highest defoliation values ​​at 2015. In hardwoods species, the highest values ​​were found in Q. pyrenaica, Q. faginea, Q. robur and C. sativa, both in the Mediterranean and Atlantic regions.

The suitability of the harmonisation and integration of the different damage networks for long-term monitoring of forest health is confirmed. These results highlight the significance of having an updated and integrated network of forest damage information as a management tool that guarantees the long-term forest sustainability