Halme, P. | Search bioRxiv

bioRxiv2024

Biodiversity impact of the consumption of peat and wood-fired district heating

The use of biofuels is becoming an increasingly important part of national and corporate climate strategies. At the same time, the consumption-based biodiversity impacts of biofuels are generally poorly known. Here we used a consumption-based approach to assess the biodiversity impacts of peat and wood-fired district heating in Finland. We combined the information on the area of impacted ecosystems and their condition before and after the impact to evaluate the impact as habitat hectares, i.e., the loss in the condition of the impacted habitats. The habitat hectare approach has not been used in previous studies on consumption-based biodiversity impacts but could be replicated to assess biodiversity impacts in different contexts around the globe. We present an eight-step general protocol for such assessment and discuss the usability of the protocol in assessing consumption-based biodiversity impacts of district heating systems. Considering different fuel types, peat had the highest biodiversity impact per unit area, followed by chips from roundwood and logging residue chips. If we consider the impacts per unit energy, chips from roundwood had the highest and peat the lowest biodiversity impact. We conclude that it is possible to assess biodiversity impacts of raw material-based consumption, like we did in our example case. This protocol should be further developed and refined in different systems and with different raw materials.

ecology↗

bioRxiv2022

Growth form matters: crustose lichens are sensitive to forest management on dead wood

Lichens have a vital role in forest ecosystems and they are a threatened group in boreal forests. However, the conservation ecology of the total lichen community has very rarely been studied. Here we studied lichen species and communities, including macrolichens (= foliose and fruticose growth forms) and rarely studied crustose lichens, on decaying wood in boreal spruce-dominated forests in Finland. We also studied obligate lignicoles that grow only on dead wood and are mostly crustose in growth form. Species richness and community composition were examined on decaying logs and natural or cut stumps of Picea abies at different decay stages (2-5) in 14 stands, half of which were natural or seminatural and half recently managed. We used thorough search to yield a species list as close to complete as possible. Our study questions were: 1) Are species richness and lichen communities different in natural and managed forests, and if so, are there differences between macrolichens, crustose lichens and obligate lignicoles in how they respond to forest management? 2) How does the decay stage and dead wood type affect the lichens, i.e. are there differences between stumps and logs? We found a total of 127 lichen species. Most (75%) of the recorded lichen species were crustose. With a generalized linear model we found that crustose lichens and obligate lignicoles had a higher species richness in natural than managed forests, but macrolichen richness was not significantly affected by forest management. Utilizing non-metric multidimensional scaling we discovered that site level community composition of macrolichens, crustose lichens and obligate lignicoles was also significantly different between natural and managed forests. We found that on dead wood unit level the decay stage had a significant effect on species richness and community composition, so that the species richness of all studied groups declined during the decay process. The dead wood type (stump vs. log) had a significant effect on species richness of macrolichens and obligate lignicoles, as well as on the communities of crustose lichens.

ecology↗