Impacts of rapid warming on radial growth of Larix gmelinii on two typical micro-topographies in the recent 30 years

Abstract

Ravine and slope are the two typical micro-topographies in the Great Xing'an Mountains. Permafrost in the two micro-topographies is extremely sensitive to global warming. To compare the differences in responses of Larix gmelinii radial growth to rapid warming in the recent 30 years, tree-ring samples were collected from northern part of Great Xing'an Mountains in Inner Mongolia and tree ring-width chronologies were developed. The results showed that the divergence between tree growth and temperature occurred in 1980 in Mo'erdaoga and in 2000 in Hanma, respectively. Since 2000, tree growth on ravine sites was greater than that on the slope stands. Chronology of two topographies reached significant level by t test in 1984-2008, the Euclidean distance was 0.937-2.742 between chronologies, and far greater than the average (0.809-1.304). The rapid warming caused a significant radial growth response in L. gmelinii to hydrothermal conditions. On the slope sites, tree growth was mainly controlled by temperature and declined gradually in recent years, while the trees growing in ravines showed an accelerating growth rate with permafrost degeneration. L. gmelinii was undergoing profound environmental pressures caused by rapid warming, and it would experience a complex growth and development process. More seriously, L. gmelinii might disappear in China with a warming climate and permafrost degeneration.