Transformation in the Forest Ecosystem of Northeastern China Driven by Human Factors Over the Past 1600 Years

Human-driven degradation of forest ecosystems has profoundly altered land cover, disrupted ecosystem functions, and contributed to climate variability. Understanding long-term changes in forest composition and resilience is crucial for developing effective, evidence-based restoration strategies. This study presents a 1,600-year paleoecological reconstruction of forest dynamics in northeastern China, based on sedimentary pollen records from Sihailongwan Maar Lake. The findings reveal that from 480 to 1930 CE, natural factors primarily governed forest dynamics, allowing for a stable adaptation of mixed coniferous and broadleaved species to climate fluctuations. However, since 1930 CE, human activities have become the dominant force, leading to significant shifts in forest structure, reduced coniferous populations, and a substantial decline in ecological resilience. This study provides an ecological baseline based on naturally driven forest dynamics, offering essential guidance for restoring a resilient mixed coniferous-broadleaved forest structure. Furthermore, these recommendations emphasize the importance of strengthening forest protection, limiting logging, and engaging local communities in conservation efforts. However, as global warming continues to accelerate, the ecological baseline derived from historical dynamics may become less applicable. This necessitates the establishment of new baselines that take future ecological changes into account.