A VEGETATION INDICATOR TO ASSESS MEDITERRANEAN PINEWOOD AFFECTED BY BAST SCALE (MATSUCOCCUS FEYTAUDI)

Abstract

The bast scale ( Matsucoccus feytaudi ) is responsible for the destruction of most of the Pinus pinaster forests in the Mediterranean area, causing resination, defoliation and subsequent death of the tree. Questions : is it possible to estimate pinewood health by analysing understory vegetation? Does the health status of pine forests changes during time? Do such variations involve understorey vegetation? What species in the understory vegetation better describe different conditions? What are the most relevant variables (defoliation and resination) influencing pine stands' condition. Location: The study area is located in the eastern part of Liguria (Italy) in pinewood affected by the bast scale Matsucoccus feytaudi . Method : we used: (1) hierarchical cluster analysis to discriminate pinewood health conditions (good and bad); (2) non-metric multidimensional scaling (NMS) to detect the most important variables influencing the pine stands' condition and understory vegetation; and (3) indicator species analysis (ISA) to determine indicator species corresponding to health conditions at the plot level. Our aim was to find a relationship between pines' health status and the variation in pinewood understory vegetation communities. Results : we found that understory vegetation composition depends on both pine stand health status and environment-related factors. Geographic variables (in particular latitude and altitude) and tree-related variables (percentage of resinated and defoliated trees) were associated with the main axes of variability of the understory vegetation. Three indicator species (Erica arborea, Quercus ilex and Castanea sativa ), which were closely linked to pine stands health status, were significantly associated with different stages of pinewood dieback caused by bast scale . Conclusion : this study provides useful information and a good operational tool for technicians working in the forestry sector, and for public administrations and land managers to start good land-use planning.