Biodiversity offsets: can we push the threshold for offsetable impacts by translocation of substrates and species?

Abstract

Biodiversity offsets: can we push the threshold for offsetable impacts by translocation of substrates and species?

Land-use have led to changes in ecosystem structures and processes, biodiversity loss, and declines in ecosystem services. However, biodiversity offsetting aimed at compensating for residual adverse biodiversity impacts arising from land-use projects potentially provides an approach that links biodiversity conservation and human development. In Sweden, biodiversity offsetts has had limited use so far, but there are expectations that an increased use of biodiversity offsets could help reduce biodiversity loss and maintain ecosystem function.

To fulfill these expectations we need to increase our understanding and knowledge regarding biodiversity offsets both from a theoretical and practical perspective. In this project we will address three main topics 1) Method development: We will evaluate a novel methods for biodiversity offset, translocation of dead wood, which potentially could push the threshold for offsetable impacts and technical solutions feasible for this novel method. 2) Currency (methods for quantifying damage): We will assess how the choice of currency (metrics to estimate biodiversity) influence biodiversity offset planning and performance. 3) Robustness of offsetting methods over time: We will develop long-term management plans for our case study and other types of biodiversity offsets based on expert knowledge and experience from national and international biodiversity offsets.

Our case study will be a unique novel large-scale long-term biodiversity offset project initiated in northern Sweden as a consequence of the expansion of the Aitik mine. To compensate for loss of ca 250 ha of forest with high or very high conservation values the Land and Environmental Court of Appeal decided that two offsets areas should be sets aside and that a large number (540) of dead wood substrate should be translocated (including associated insects, epiphytes and wood fungi) from the impact area to the compensation area. To allow for a scientific evaluation of this project we conducted baseline measures of insects, bryophytes and wood fungi in both impact and compensation areas as well as the reference landscape prior to the translocation in 2017. In addition, we have designed a field experiment were we vary the number of translocated dead wood substrates in 30 plots in the 400ha large compensation area. Beginning in 2018 we will monitor survival and spread of translocated species using trapping, field inventories and molecular methods with regular intervals.

Never before have deadwood translocation of this magnitude been undertaken making this project unique and we basically lack knowledge regarding the outcome of these translocation, i.e. if translocated species will survive and establish in the compensation area. But if the method is successful it could be extremely useful in biodiversity offsetting and ecological restoration.