20^th-century ecological disasters in central European monoculture pine plantations led to critical transitions in peatlands

Abstract. The frequency of extreme events worldwide is steadily increasing. Therefore, it is crucial to recognize the accompanying response of different ecosystems. Monoculture tree plantations with simplified ecosystem linkages are particularly vulnerable to catastrophic events like fires, wind throws, droughts and insect outbreaks. These events threaten forests and other associated ecosystems, including peatlands, which are extremely important in regulating the global carbon cycle and thus mitigating the effects of a warming climate. Here, we examined how a peatland in one of Poland's largest pine plantation complexes responded to some of the largest environmental disasters observed in the 20^th century across Central Europe – the 1922–1924 outbreak and the 1992 fire. As a disturbance proxy, we used a multi-proxy palaeoecological analysis supported by a neodymium isotope record. We showed several critical transitions in the peatland associated with extreme events and anthropogenic impacts, which triggered significant changes in the peatland’s ecological status.