Climate change alters forest development pathways, with consequences for ecosystem services and biodiversity. As the rate of warming increases, ecosystem change is expected to accelerate. However, ecosystem dynamics can have many causes unrelated to climate (for example, disturbance and stand development legacies). The compound effects of multiple drivers remain largely unclear. Here, we assessed forest dynamics over 28 years at Berchtesgaden National Park (BGNP), Germany, quantifying the spatiotemporal patterns and unraveling the drivers of forest change. We analyzed high-density forest inventory data, consisting of three consecutive censuses of 3759 permanent sample plots (132,866 tree records in total). We used semi-variograms to analyze spatial patterns of change, and boosted regression trees to quantify the effect of 30 covariates on changes in nine indicators of forest structure and composition. Over the 28 years investigated, the forests of BGNP were becoming denser, structurally more complex, and more species rich. Changes in forest structure were more pronounced and spatially correlated on the landscape than changes in tree species composition. Change rates of all indicators increased over time, signifying an acceleration of forest dynamics since the 1980s. Legacies and climate were the most important drivers of change, but had diverging impacts. Although forest change accelerated with increasing temperature, high legacy levels typical for late development stages dampened it. We here provide evidence for accelerating forest dynamics in mountain forests of the Alps, with potentially far-reaching consequences for biodiversity and ecosystem processes. We highlight that unmanaged forest development toward old-growth conditions could counteract climate-mediated acceleration of forest change.

气候变化改变了森林发展路径，对生态系统服务和生物多样性产生了影响。随着变暖速度的加快，预计生态系统变化将加速。然而，生态系统动态可能有许多与气候无关的原因（例如，干扰和林分发展遗产）。多种驱动因素的复合效应在很大程度上仍不清楚。在这里，我们评估了德国贝希特斯加登国家公园 (BGNP) 28 年来的森林动态，量化了时空模式并揭示了森林变化的驱动因素。我们分析了高密度森林清单数据，包括 3759 个永久样地（总共 132,866 个树木记录）的三个连续普查。我们使用半变异函数来分析变化的空间模式，并增强回归树以量化 30 个协变量对森林结构和组成的九个指标变化的影响。经过 28 年的调查，BGNP 的森林变得越来越密集，结构越来越复杂，物种也越来越丰富。与树种组成的变化相比，森林结构的变化在景观上更为明显且空间相关。所有指标的变化率随着时间的推移而增加，表明自 1980 年代以来森林动态加速。遗产和气候是变革的最重要驱动力，但产生了不同的影响。尽管森林变化随着温度的升高而加速，但后期发展阶段典型的高遗留水平抑制了它。我们在这里提供了加速阿尔卑斯山森林中森林动态的证据，对生物多样性和生态系统过程可能产生深远的影响。我们强调，未经管理的森林向老生长条件发展可以抵消气候介导的森林变化加速。