Veteran trees in decline: Stratified national monitoring of oaks in Norway

Old veteran trees function as biodiversity hotspots in both forests and open landscapes, protecting such is an important measure to halt loss of biodiversity. Nevertheless, the number continues decline worldwide, although estimates this mainly stem from geographically restricted case studies. In Norway, oak have received special protection since 2011 through Norwegian Biodiversity Act, however, there a lack knowledge on status trends for these trees. A national monitoring program was started 2012, using random, stratified sampling procedure. We use data baseline survey first revisit estimate total well mortality oaks Norway. Further, we assess recruitment potential (in survey) changes variables describing ecological state regrowth. The area covered geographical distribution Norway divided into > 200 000 plots 500 × m. set were randomly selected two strata: High probability (n = 100; with high occurrence oaks), Low 400), existing databases. Plots surveyed over five year-period (2012–2016), 20 HighProb-plots 80 LowProb-plots each year. All that observed during revisited 2019, three seven years after they initially registered. Tree absence cause death/change recorded. estimated 138 100 based survey, which 25 could be denoted “top quality oaks”. Based revisit, 7 600 trees, i.e., annual rate 1.2%. Recruitment present most oaks, but category slow unlikely balance out rate. More precise should prioritized future monitoring. far exceeds appr. 10 registered database, clearly demonstrates need continued mapping improve foundation knowledge-based land management. short-term hotspot pivotal source ecosystem functions, despite increased recent years. Our results conclusions are relevant also other species than oak.