Abundance and diversity of edible wild plants in managed boreal forests

Abstract

Boreal forests are rich in non-timber forest products from plants: wild berries and herbs used commercially or by households as food, medicine, decoration, or raw material. Approximately two hundred wild plant species have been documented for their nutritional uses in Finland, and many of these species occur in forests. However, the provisioning of edible plants by managed forests has received little attention, despite the fact that forest vegetation is altered by forest management practices. In this study, we use nation-wide forest vegetation and tree stand data consisting of a total of 1,778 sample plots to quantify the richness and abundance of edible wild plants in Finnish forests. Responses of edible species richness, abundance, and composition to stand characteristics such as site type, tree species composition, stand density, and management history are analyzed with regression models, NMDS ordination, and diagnostic species analysis, for forests on mineral soils and on peatlands separately. A total of 68 edible wild plant species occur in our dataset, with their occurrence and abundance varying between species and between sites. Our results indicate that habitat characteristics, namely site fertility and stand density, are the strongest determinants of overall edible plant provisioning. The richness of edible species as well as their total abundance were lower in less fertile site types and in denser stands. Recent timber harvesting and plantation as opposed to natural regeneration had a negative effect on edible species abundance in mineral soil forests. Several edible plant species confined to the richest site types accounted for the increase in species richness, while different forest management practices had generally none or a negligible number of diagnostic species. We conclude that a large and diverse set of edible wild plants occurs in Finnish forests, and the effects of stand characteristics and management on overall edible plant richness and abundance may be muddled by opposite species-level responses. Edible plant provisioning should be further analyzed at the level of smaller species groups or individual species to reveal the opportunities to support it in managed forests.