Latitudinal trends in vegetation productivity of permafrost wetlands in Great Hing´an Mountain valleys and its response to global change

The permafrost wetlands in the Great Hing´an Mountain valleys are degenerating in response to climatic warming and retreat of permafrost. Changes in vegetation productivity are an important aspect in the studies on permafrost wetlands in response to global change. We investigated the vegetation productivity aboveground in the 12 permafrost wetlands in the Great Hing´an Mountain valleys along a latitudinal gradient. The results indicated a significant latitudinal gradient in herbage productivity, which was determined primarily by temperature. Linear regression demonstrated an 80 g· m^-2 increase in herbage productivity with an increase of annual temperature by 1°C. If temperatures increased 2-4°C over the next century, herbage productivity would increase 2-4 times in predominantly continuous permafrost, and 57-114% in island permafrost. Shrub productivity and community productivity had no significant relationships with latitude, but they tended to increase first, and then decrease with the increase of mean precipitation in July.