Semiarid forests are experiencing unprecedented hotter drought, which could have a profound impact on tree growth. In addition to increasing temperature, the warming climate may cause more frequent and intense heatwaves further increasing the stress on tree growth. In this study, we measured tree ring width of 1139 cores collected from 12 Siberian larch (Larix sibirica) forest patches in the northern Mongolian Plateau to investigate how heatwaves affect tree growth. Our results showed a coupled relationship between tree growth and heatwaves that indicated by the extreme-hot days before 1996. After 1996, there was an increased frequency of heatwaves, which has strongly reduced tree growth, with an 8.4% growth decline in large forest patches (> 10 ha), 48.1% decline in medium patches (3–10 ha), and 39.2% decline in small patches (< 3 ha), respectively. The tree growth-heatwave relationship remained in medium and small forest patches after 1996, however, it became decoupled in large forest patches (p > 0.05), potentially through the effects of decoupled soil water-heatwave relationship in large forest patches that mostly located on thick soils. Our observations indicated that current climate warming and frequent heatwaves may have exceeded the favorable growth conditions of Siberian larch, but landscape heterogeneity (patch size and slope position) can alleviate the pressure of temperature warming and reduce tree growth rapid decline under high-frequency heatwaves climate in Mongolia Plateau.

半干旱森林正在经历前所未有的高温干旱，这可能对树木的生长产生深远的影响。除了温度升高外，气候变暖可能会导致更频繁和更强烈的热浪，进一步增加对树木生长的压力。在这项研究中，我们测量了从 12 棵西伯利亚落叶松 ( Larix sibirica) 蒙古高原北部的森林斑块，以研究热浪如何影响树木的生长。我们的研究结果表明，1996 年之前的极端炎热天气表明树木生长与热浪之间存在耦合关系。 1996 年之后，热浪频率增加，大大减少了树木生长，大片森林的生长下降了 8.4% （> 10 公顷），中斑块（3-10 公顷）分别下降 48.1%，小斑块（< 3 公顷）下降 39.2%。1996 年后中小森林斑块中树木生长-热浪的关系仍然存在，但在大森林斑块中它变得脱钩（p > 0.05)，这可能是由于在主要位于厚土壤上的大森林斑块中解耦土壤水-热浪关系的影响。我们的观察表明，当前气候变暖和频繁的热浪可能已经超出了西伯利亚落叶松的有利生长条件，但景观异质性（斑块大小和坡位）可以缓解气温升高的压力，减少高频热浪气候下树木生长的快速下降。在蒙古高原。