Do trees on agrarian stone walls respond to contemporary climate warming?

Agrarian stone walls and associated landscapes are present in different parts of Central and Western Europe. Somewhere they are conserved as valuable components of cultural landscapes whereas elsewhere they do not have any formal conservation status. These stone walls and the habitats connected to them host many old trees, which are potential archives of environmental changes. In the available literature there are practically no studies looking at the archival value of trees on agrarian stone walls. In our study we investigated sycamore maples growing on stone walls in the Ore Mts region of Czechia. We focussed on annual wood growth using dendrochronological methods and carried out pointer year analyses to examine environment-growth relationships. Our main findings suggest moderately heterogeneous growth among individuals within sites but that there is a common environmental response apparent in overall site chronologies. We observed low inter-series correlations within sites but only a fair to moderate Gleichläufigkeit and express population signal among ring width series at most of the study sites. Generally, we revealed mostly significant positive correlations with precipitation and negative correlations with increasing temperatures over the last years. From climate correlations analysis and pointer year analysis we could clearly infer that (1) tree growth on agrarian stone walls at three out of four of our sites is significantly impacted by current climate change and that (2) these trees have a good ecological-archival value because they are sensitive to contemporary warming; they should therefore be identified to be given a relevant conservation status and management.