Scots pine (Pinus sylvestris L.) forests of many inner Alpine valleys have recently displayed a quick loss of vitality. A decline-disease has been suggested as the cause, with drought as the main predisposing factor and the additional contribution of biotic agents inciting tree dieback. This study is focused on the Valle d'Aosta, a dry, inner- Alpine region in NW Italy. We inferred vitality changes between years 2000 and 2007 by computing reductions of enhanced vegetation index (EVI). Image differencing was carried out on pre-processed MODIS imagery taken in late springtime and validated against ancillary ground truth. We: (1) tested whether EVI reductions in Scots pine forests were significantly higher than those of a control species, and of a wetter region for the same species, (2) analyzed decline incidence as a function of site and topographic variables, (3) assessed the relative influence of site and stand structure on decline probability by means of path analysis. Mean EVI in the study area actually increased due to an early onset of the 2007 growing season. Nevertheless, the incidence of decline was 6.3%, and significantly greater for Scots pine than the control species and site. Low-elevation, northerly-exposed sites exhibited the highest incidence of decline. Path analysis suggested that the most important determinants of decline probability were slope, incoming radiation, and stand sparseness.
Evidences of drought stress as a predisposing factor to Scots pine decline in Valle d'Aosta (Italy)
VACCHIANO, GIORGIO;BORGOGNO MONDINO, ENRICO CORRADO;GARBARINO, MATTEO;MOTTA, Renzo
2012-01-01
Abstract
Scots pine (Pinus sylvestris L.) forests of many inner Alpine valleys have recently displayed a quick loss of vitality. A decline-disease has been suggested as the cause, with drought as the main predisposing factor and the additional contribution of biotic agents inciting tree dieback. This study is focused on the Valle d'Aosta, a dry, inner- Alpine region in NW Italy. We inferred vitality changes between years 2000 and 2007 by computing reductions of enhanced vegetation index (EVI). Image differencing was carried out on pre-processed MODIS imagery taken in late springtime and validated against ancillary ground truth. We: (1) tested whether EVI reductions in Scots pine forests were significantly higher than those of a control species, and of a wetter region for the same species, (2) analyzed decline incidence as a function of site and topographic variables, (3) assessed the relative influence of site and stand structure on decline probability by means of path analysis. Mean EVI in the study area actually increased due to an early onset of the 2007 growing season. Nevertheless, the incidence of decline was 6.3%, and significantly greater for Scots pine than the control species and site. Low-elevation, northerly-exposed sites exhibited the highest incidence of decline. Path analysis suggested that the most important determinants of decline probability were slope, incoming radiation, and stand sparseness.File | Dimensione | Formato | |
---|---|---|---|
2012 EJFR_Vacchiano_Post_print.pdf
Accesso aperto
Tipo di file:
POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione
988.71 kB
Formato
Adobe PDF
|
988.71 kB | Adobe PDF | Visualizza/Apri |
Vacchiano_et_al_2011.pdf
Accesso riservato
Tipo di file:
PDF EDITORIALE
Dimensione
511.7 kB
Formato
Adobe PDF
|
511.7 kB | Adobe PDF | Visualizza/Apri Richiedi una copia |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.