The value of information in conservation planning: Selecting retention trees for lichen conservation

Conservation planning studies at small scales such as forest stands and below are uncommon. However, for retention forestry, developed during the last two decades and with current wide and increasing application in boreal and temperate regions, the need for cost-effective selection of individual trees is evident. In retention forestry certain trees are left at final harvest to promote flora and fauna. There is also a scarcity of studies on information costs and how these relate to the cost-effectiveness of conservation. We addressed both of these issues by studying whether decisions about the retention of aspen Populus tremula L. trees can be made more cost-effectively by including information about tree characteristics. We analyzed data from 12 recently harvested stands in middle Sweden containing 131 epiphytic lichen species (a biodiversity proxy) on 360 aspen trees. We related the presence of lichen species to bark and stem attributes and used those relationships to prioritize trees for retention. We estimated the value of using different sets of survey information (lichens, tree characteristics) to select retention trees to achieve various conservation goals. Depending on species or species groups of interest, and the type of tree information being collected, the value of collecting the information is up to 20% of the total value of all potential retention trees, which, given current labor costs, allows up to four hours for planning and selecting the right trees on an average-sized clearcut. The current practice of almost randomly selecting aspen trees to retain at final harvest can be improved by adding easily collected information on tree characteristics, such as black-colored bark, slow tree growth, inclining stems and speckled bark. This can lead to attainment of a given level of a conservation goal (like maximizing the number of lichen species of conservation concern) with fewer retention trees. Inventory of tree information often can be performed quickly, and if part of the gains from using such information to guide tree selection would be spent on additional conservation efforts, this would benefit biodiversity. Studies on more organism groups and tree species are needed to increase the applicability of results.