Natural and artificial regeneration of ash stands is under direct impact of numerous biotic and abiotic factors, many of which seriously hamper the viability of ash. Insect pests, pathogenic fungi, large game ungulates and ruminantes and small rodent populations play dominant role in the complex processes of tree decline and stand deterioration. Additionally, in the course of recent Europe-wide dramatic spread of newly identified lethal disease on ashes (Chalara fraxinea), introduction of a highly damaging Emerald Ash Borer (Agrilus planipennis) on the eastern borders of Europe, and increased frequency of climatic extremes urge the need to intensify the research of this phenomena. Through an integrated, multidisciplinary approach, in the course of 4 years, the proposed research project targets on several critical aspects of aforementioned biotic detrimental factors analyzing them in the given area and time and aiming to provide a multitude of new details on the mechanisms of their impact. Modern methodological approach covers the following major research topics: presence, local impact and ash disease spread and host resistance tests; additive impact of ash defoliators in the course of recent decline and possibility to manage their populations via entomopathogenic organisms; the impact of small rodents on tree regeneration, acting also as an important human diseases reservoir; negative impact of large game in ash regeneration; geospatial and temporal analysis of major biotic influences in given forest communities.
Close to half of the Croatian flood plain forests (67.470 ha) are represented by narrow-leaf ash, covering 29.748 ha
in major river basins.
Respective welfare of Croatian flood plain forests amount to 6.4 billion €,
2.8 billion € being attributed exclusively to ash forests.
Growing stock in narrow-leafed ash forests reaches 4.3 million m3, binding 11.8 million tons of carbon dioxide acting as an important carbon sink depository.