Changes in forest structure drive temperature preferences of boreal understory plant communities

1. The local climate in forest understories can deviate substantially from ambient conditions. Moreover, forest microclimates are often characterized by cyclic changes driven by management activities such as clear-cutting and subsequent planting. To understand how and why understory plant communities change, both ambient climate change and temporal variation in forest structure has to be considered. 2. We used inventories from 11436 productive forest sites in Sweden repeated every 10th year 1993 - 2017 to examine how variation in forest structure influences changes in the average value of minimum and maximum temperature preferences of all species in a community, i.e. community temperature indices (CTI). We then evaluated to what extent these changes were driven by local extinctions and colonizations, respectively, and to what extent the difference in CTI value between two inventories were related to changes in forest density and in macroclimate. Lastly, we tested whether effects on CTI ...