Temperature sensitivity of tree recruitment at alpine treelines increases along latitudinal gradients

Abstract

The alpine treeline is highly sensitive to temperature change, and treelines worldwide have been rapidly responding to temperature warming by increasing in tree density. However, often inconsistent or even conflicting results, regarding the response of tree recruitment to temperature change across regions, still challenge our profound comprehension of warming‐induced treeline dynamics. Here, we quantified the temperature sensitivity of tree recruitment within alpine treeline ecotones (i.e. the strength of relationship between tree recruitment and temperature change), and tested whether and how the temperature sensitivity changed along latitudinal gradients by examining 124 alpine treelines across North America and Asia. Our analyses demonstrated that temperature changes could significantly influence tree recruitment at treeline ecotones and the sensitivity of tree recruitment to temperature change was significantly and positively associated with latitude, showing that tree recruitment was more sensitive to temperature change at high latitudes than at low latitudes. Our findings highlighted the heterogeneous responses of tree recruitment at alpine treelines to temperature changes across latitudinal gradients, which should be incorporated into assessment models to improve future projections of global warming impacts across alpine ecosystems.