Conserving boreal forest biodiversity: does landscape structure matter for forest-dwelling lichens?

Forest biodiversity has decreased worldwide due to intensive forestry. This is also the case in Sweden, where a majority of forests is managed for wood production: the current management practices have led to significant negative impacts on the diversity of forest-dwelling species, and efficient conservation strategies are therefore needed to change this development and halt the loss of forest biodiversity. These strategies have to consider several spatial scales, from individual trees to whole forest landscapes, because processes operating at multiple scales are important for species diversity. In other words, it is necessary to understand not only which types of conservation measures are efficient at local scale, but also how they should be distributed within forest landscapes to achieve the highest possible benefit for biodiversity.

In my research, I have aimed at finding ways to maintain species diversity in managed boreal forest landscapes, focusing especially on forest-dwelling lichens. Lichens are a diverse group with over 2 200 species known from Sweden. However, their diversity is declining: in the latest Swedish red list, 22% of the evaluated lichen species were classified as red-listed.

Many of these are forest-dwelling species, and forest management is currently recognized as the most serious threat to lichen diversity in Sweden: it destroys important lichen habitats, such as old deciduous trees and dead wood, and disrupts both spatial and temporal habitat continuity.

In this lecture, I will talk about how to maintain the diversity of forest-dwelling lichens in managed forest landscapes. I will give a short background of the effects of current forest management practices on lichens, and of the different conservation measures that can be applied on local scale, i.e. within individual forest stands. These measures can include, for example, creation and preservation of lichen habitats, such as dead wood. Their effects on forest-dwelling species – both lichens and other taxa – are relatively well studied.

However, what we still know less about is the importance of landscape: how do the amount and spatial arrangement of suitable habitats, e.g. dead wood, within a forest landscape affect lichen diversity, at how large scales such effects occur, and what are the implications for biodiversity conservation? The main focus of my lecture will be on these landscape-scale processes: I will summarize what is known on the importance of landscape structure for lichen diversity, and how this should be considered in practical conservation strategies.

I will conclude the lecture with potential directions for future research. Further research on the effects of landscape structure is still required to inform conservation planning, especially when it comes to sessile, passively dispersing species such as lichens. I am particularly interested in combining this research with novel survey methods, such as environmental DNA that can enable the collection of species diversity data over much larger spatial scales than what is feasible through traditional field surveys, and thus provide new opportunities for studying species diversity at landscape scale.