Naturally regenerated English oak (Quercus robur L.) stands on abandoned agricultural lands in Rilate valley (Piedmont Region, NW Italy)

Abstract

The present study was carried out in 14 sites located in Rilate valley, a hilly area in the south-east Piedmont (NW Italy) within the Monferrato district. Sites were selected where naturally regenerated forest communities are developing on abandoned crop lands. Altitude ranges from 190 to 240 m a.s.l., while the abandonment period varied from 1 to 50 years at the time of the surveys (year 2007). The presence of younger stands (i.e., stands with age < 12 yrs) demonstrates a rapid invasion of abandoned farmlands by forest communities dominated by English oak mixed with other hardwoods, such as wild cherry and common elm. Observations conducted in older stands (i.e., stands with age ranging between 20 and 50 yrs) confirm the ability of English oak to generate well structured woodlands in the study area. In these environmental conditions previous cropping and exposure seem to play a significant influence on stand characteristics. Other noble hardwoods, such as wild cherry and common elm, are frequently associated with the oak. These stands showed a mean annual increment varying from 4 to 6 m3 ha-1 year-1 at the age of 45-50 yrs. At the present, black locust is only sporadic in the uppermost canopy layer and generally confined in the understory. The rapid colonization by Q. robur is favoured by the presence of adult oak trees in the field edges, providing abundant acorns efficiently dispersed by small rodents and birds. Oak stands observed in this study are worthy of notice in the light of the current decline of many adult oak communities in northern Italy, as well as for their potential to produce lumber and veneer logs. Therefore, these stands should be preserved avoiding coppicing or other irrational cuts. Further studies would be needed to analyze the contribution of soil characteristics to the colonization processes. © iForest - Biogeosciences and Forestry.