c8.12.22 – Missing growth of Norway spruce due to fungal root and butt rot infection

La Porta N (1), Gori Y (1), Camin F (2), Cherubini P (3)

(1) Sustainable Agro-ecosystems and Bioresources Department, IASMA Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all’Adige, (TN), Italy; (2) FEM-IASMA Via E. Mach 1, 38010 San Michele a/Adige (Trento); (3) Food Quality and Nutrition Department, IASMA Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 San Michele all’Adige, (TN), Italy
Collocazione: c8.12.22 – Tipo Comunicazione: Poster
8° Congresso SISEF *
Sessione 12: “Poster” *

Contatto: Nicola La Porta (nicola.laporta@iasma.it)

Abstract: Heterobasidion annosum s.l. causes root butt rot and tree mortality and is widely regarded as the most economically serious threat in northern boreal conifer forests being particularly dangerous in weakening root system and increasing the risk windfall. The rate of spread within the heartwood varies depending on the vitality of the trees and on moisture content of the wood. H. annosum s.l. spread depends largely on stand type and history, forest composition and soil properties. This serious pathogen causes significant economic losses in different ways: mortality, windthrow, decreasing of quality of wood as a result of wood decay, and indirect loss caused by growth reduction. Up to now economic losses are often underestimate as they are based only on the decay of the lower part of the inner stem and its consequent deprecation for timber use while indirect losses, like growth reduction, are not considered. However, shoot and stem pathogens may reduce growth by interfering with the movement of water, nutrients and assimilates in the stem and branches. Root pathogens disturb the water uptake and nutrition of the trees, thus affecting growth indirectly and may influence the effects of the other diseases on growth. According to climate change scenarios it is expected an increase in drought stress throughout Europe, with a likely substantial alteration in the structure and functioning of terrestrial ecosystems. Climate warming could alter the incidence and geographical range of pathogens and hosts, it could change the occurrence and intensity of tree diseases, modify host resistance and result in changes in the physiology of tree-pathogen interactions. An increased incidence of summer drought would probably favour diseases caused by fungi and increase tree mortality. Therefore, of particular concern is to study the abilities of trees at the stand and structure level to respond to pathogenicity of fungi, since tree-pathogen interactions are strongly influenced by environmental conditions. To date, however, there are few studies on the interactive effects of environmental factors and fungi on forest trees and the available results mostly derive from experiments based on potted individuals or on plantations. Dendrochronology has been used: to determine the calendar year of tree death and as an indicator of tree health in several studies. It was also used as a tool to measure growth reductions associated to invasion of woody tissues by root-rot fungi and can be used as record about the past environmental stresses and disturbances. By tree-ring growth we will improve our current understanding on plant-pathogen interactions and on host resistance to disease at forest ecosystem level. Our hypothesis is that the combination of increasingly warmer temperature and dried years in warmer sites, could drastically decrease host resistance and trigger the widespread increasing of tree mortality. In this study we used a tree ring-proxy analysis to analyse the impact of the fungus Heterobasidion parviporum, the Heterobasidion species host specialized for Picea abies. Many studies have been carried out to estimate the wood losses of this disease, however, a significant gap of knowledge is still present on the growth failure caused by this pathogen. The aim of this study was to test the potential of tree ring analysis to estimate the missing growth due to H. parviporum infection on Norway spruce. Three Norway spruce mature stands infected by H. parviporum were selected for sampling in the South-Eastern Alps: Baselga (BAS), Val Maggiore (VAL) and Cermis (CER) at different altitude respectively at 850-900, 1300 and 1950 m a.s.l. Health (HT) and infected trees (IT) were sampled. The main goals of the study were: (1) to clarify the role of climate conditions on infected trees by analyzing the climate-growth relationship at forest ecosystem level; (2) to forecast the development of this pathogen under a climate warming trend; (3) to estimate the indirect volume losses due to the prolonged presence of the fungus within the wood, on different managed forest in the Eastern Alps; (4) to test the hypothesis that tree-ring patterns may be used as an indicator of tree health, drought susceptibility and physiological change of infected trees. IT ring width was significantly lower than that of the control trees (HNS) with average basal area losses of 45% at Baselga and 49% at Val Maggiore, and only 30% at Cermis. (Fig. 2). HT growth rates were significantly reduced with time at each site. When crossdated samples were used to identify period of growth suppression as “abrupt growth reduction”, were observed significant tree-ring growth divergence observed at Baselga, Val Maggiore and Cermis commencing in 1980, 1965 and 1945 respectively.

Parole chiave: Dendroecology, Growth Reduction, Drought Stress, Fungal Infection

Citazione: La Porta N , Gori Y , Camin F , Cherubini P (2011). Missing growth of Norway spruce due to fungal root and butt rot infection . 8° Congresso Nazionale SISEF, Rende (CS), 04 – 07 Ott 2011, Contributo no. #c8.12.22