Faktorer som påverkar marklavars höjd i boreala områden : Effekter av renskötsel och skogsbruk i norra Sverige

There are indications that lichen-rich areas in northern Sweden, commonly used for winter grazing by semi-domesticated reindeer (Rangifer tarandus), has declined by 30-50% since the 1950s. This is mainly believed to be because of a rise in clear-cutting activities during that time period. With fewer areas for the reindeer to conduct their winter grazing it is important to know how grazing activities potentially affect the ground lichen. This report investigates what variables, such as tree density and reindeer grazing intensity, affect the height of five ground lichens; four Cladonia and one Cetraria species. The research was conducted in Norrbotten and Västerbotten, with a total of 55 sample plots, during the month of July 2015. Previous National Forest Inventory plots with a ground cover of at least 25% reindeer lichen were used. The commonly found species were Cladonia rangiferina and Cladonia arbuscula/mitis. Grazing intensity from reindeer had a low explanatory power on the variation in the mat-forming lichen height in boreal forests if considered by itself (R2=0.05, p=0.06). Instead, reindeer grazing effects became more evident when considering an interaction with the tree density of the forest. Tree density and grazing pressure have an important role for lichen height, but there probably are more variables which, directly or indirectly, affect lichen height. Tree density also effects the amount of reindeer found in the area and seems to be of great importance when reindeer graze during the winter

Modelling occurrence and status of mat-forming lichens in boreal forests to assess the past and current quality of reindeer winter pastures

Lichens play an essential role in northern ecosystems as important contributors to the water, nutrient and carbon cycles, as well as the main winter food resource for reindeer (Rangifer tarandus, also called caribou in North America), the most abundant herbivores in arctic and subarctic regions. Today, climate change and several types of land use are rapidly transforming northern ecosystems and challenging lichen growth. Since lichens are important indicators of ecosystem health and habitat suitability for reindeer, large-scale assessments are needed to estimate their past, present and future status. In our study, we aimed to develop models and equations that can be used by stakeholders to identify the occurrence of lichen-dominated boreal forests and to determine lichen conditions in those forests. Data were collected in Sweden and most input data are publicly available. We focused on mat-forming lichens belonging to the genera Cladonia and Cetraria, which are dominant species in the reindeer and caribou winter diet. Our models described lichen-dominated forests as being dominated by Scots pine (Pinus sylvestris), having low basal area and thin canopy cover, and being located in south- and west-facing areas with high summer precipitation, low winter precipitation and temperature, and on gentle slopes. Within those forests, lichen biomass was positively related to tree canopy cover and summer precipitation, while negatively and exponentially related to intensity of use of the area by reindeer. Forest, meteorological, topographic and soil data can be used as input in our models to determine lichen conditions without having to estimate lichen biomass through demanding and expensive fieldwork