Climate, vegetation, and human influences on late-Holocene fire regimes in the Sanjiang plain, northeastern China

Understanding the fire evolution history and its driving mechanisms can provide useful insights into the fire regimes and their potential impacts in the future. Here, we present a well-dated peat profile with high-resolution charcoal and pollen records to reconstruct the fire and vegetation history in the Sanjiang Plain over the last 6000 yr. The regional and local fire frequencies were reconstructed with the microscopic (< 125 μm) and macroscopic (> 125 μm) charcoal fractions, respectively. During the interval ~ 6.0-4.5 ka BP, both the regional and local fires exhibited much low frequencies responding to the strong summer monsoon. Thereafter, the fire frequencies increased significantly with the decline of the summer monsoon, and the highest frequencies corresponded well with the weak monsoon intervals around 4.0, 2.7, and 0.8 ka BP. As for the local fires, in addition to the climate changes, the local vegetation conditions have also served an important role in driving their occurrences. During the last 300 yr, the gradually increased fire frequencies were attributed to the intensified human activities instead of the climate and vegetation influences.