Allocation and size of conservation measures in a production boreal forest landscape: insights from applying the Delphi technique

Abstract

This study aims to assess the effects of spatial allocation and size of individual conservation measures on provision of ecosystem services and preservation of biodiversity in a production forest landscape. Since it is difficult to get a complete picture of the long-term outcome using only empirical studies, we combined simulations with an expert assessment method – the Delphi technique. Using data from a forest landscape of 15000 ha in central Sweden we constructed seven scenarios. In all of them 2% of total area is allocated to each of the following measures representing untouched areas of different sizes: nature reserves (approximately 100 ha each), set asides (less than 50 ha each) and groups of retention trees. In six scenarios additional 10% of total area was allocated to one of the three categories either dispersed around the whole landscape or concentrated in a sub-landscape (the latter constitute approximately 30% of the studied landscape). In the seventh scenario rotation of production areas was extended so that net present value was comparable to that of other six scenarios. We then simulated development of each scenario for 100 years using Heureka – a Swedish forestry decision support software.

We employ the Delphi technique to investigate seven constructed scenarios for provision of several ecosystem services and maintenance of biodiversity. The technique represents a moderated group communication process in which participating experts independently of each other fill out an online questionnaire in a series of rounds. The experts are scientists who have been working in the field of either forest biodiversity or selected ecosystem services in the boreal zone of Scandinavia. They are provided with information about the studied landscape and outputs from simulations of forest development during the next 100 years in form of maps and figures. For each question experts also are asked to provide a confidence rating they have in their answer as well as record comments that could be helpful in explaining their answers to others. The latter is particularly important since there is no direct interaction between experts (each of them communicates with the moderator only). After each round the moderator sends to experts a report summarizing group results and comments from previous round together with the updated questionnaire. After they have studied the materials they are invited to reconsider their answers in the light of group summary (change in answers is up to the participant). The process continues until stability in answers is reached.

We will discuss: a) which size of unmanaged areas is considered best for different services; b) which strategy is considered more beneficial for services: dispersed or concentrated; c) degree of agreement between scientists and levels of confidence they have in their estimates; and d) factors that could explain range of obtained estimates.