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

Alpine treeline is highly sensitive to temperature change, and treelines worldwide have been rapidly responding to temperature warming by increasing 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 identified the temperature sensitivity of tree recruitment within alpine treeline ecotones (i.e., the strength of the 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 ..., ,

高山林线（alpine treeline）对气温变化高度敏感，全球各地的林线正通过提高树木密度快速响应气候变暖。然而，不同区域间树木更新（tree recruitment）对气温变化的响应结果往往不一致甚至相互矛盾，这仍制约着我们对气候变暖驱动的林线动态的深入认知。本研究明确了高山林线交错带（alpine treeline ecotones）内树木更新的温度敏感性（temperature sensitivity，即树木更新与气温变化之间的关联强度），并通过考察北美与亚洲共计124处高山林线，检验了该温度敏感性是否沿纬度梯度（latitudinal gradients）发生变化，以及具体的变化模式。分析结果表明，气温变化可显著影响林线交错带内的树木更新，且树木更新对气温变化的敏感性与纬度呈显著正相关，表现为树木更新……