Disentangling the effects of seminatural forestry on an ecosystem good: Bilberry (Vaccinium myrtillus) in Estonia

•Incorporating bilberry in forestry planning requires site type specific approach.•Ditching has been a major cause increasing bilberry cover in bog landscapes.•Even-aged forestry conflicts with bilberry production most in Podzol sites.•Solitary retention trees are insufficient for maintaining good bilberry sites.•Distributional shifts can affect ecosystem goods without change in abundance.

Management impacts on dominant and keystone species form a major sustainability issue in forests, because such impacts can affect production of ecosystem goods and trigger extinction cascades. On acidic soils in northern forests, bilberry (Vaccinium myrtillus L.) is a well-known field-layer plant that is important culturally and as food for wildlife and humans, and is affected negatively by intensive forestry. In this paper, we analyse bilberry performance in a semi-natural forestry system (based on multiple native tree species and largely natural regeneration); specifically in relation to two major silvicultural activities-timber harvest and wetland drainage. We combined plot- and landscape-scale data from a range of forest types varying in soil moisture and nutrient richness in Estonia, and compiled a landscape retrospective of bilberry abundance. Clear-cutting sharply reduced bilberry abundance on mineral soils and green-tree retention only slightly mitigated that impact; however, in drier sites, some recovery had started in 10 years. By the mature stage of production forests (60-80 years post clear-cutting), bilberry cover had recovered to the levels observed in old growth. Artificial drainage increased bilberry cover on poor peat soils, and partial cutting of drained pine forests further enhanced it. A retrospective analysis of these patterns in a forest-wetland landscape revealed a net increase in bilberry cover and berry production during the past 70 years. We conclude that the studied forestry system has increased bilberry cover in boggy areas with likely benefits to some herbivores (e.g. grouse) at the expense of wetland species; however, negative effects of clear-cutting prevail in dry pine forests that are the preferred berry-picking sites for humans.

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