Land use and cover change in Northeast China and its impacts on the
Xing'an permafrost in 1980-2020
Abstract
Vegetation plays important roles in the development and protection of
permafrost; it is one of the main local and ecosystemic factors that
affect the thermal stability of the underlying soil strata. Multi-period
land use and cover change (LUCC) data and long-time series of air
temperature were chosed. Based on these data, spatiotemporal changes in
mean annual air temperature (MAAT) were simulated by the Ordinary Least
Squares (OLS) method and Ordinary Kriging (OK) model in the 1980s-2010s
in Northeast China. The influences of LUCC on MAAT in Northeast China
and distribution of the Xing’an permafrost were analyzed and the results
showed that: (1) Decadal average of MAAT increased from 4.60oC (1980s)
to 5.38oC (2010s) in Northeast China, with an upward trend of
0.25oC/10a. (2) During the 1980s to 2010s, the total permafrost area
showed a decreasing trend (3.668×104 km2/10a). (3) In permafrost
regions, LUCC had undergone significant structural changes: forested
land showed a consistent decreasing trend and other lands showed an
overall increasing trend. (4) The effects of different LUCC on MAAT in
the permafrost region varied substantially. The mean MAAT of forested
land was the lowest (2.33oC), and; that of unused land, the highest
(0.37oC). The change rate in MAAT of cultivated land was the highest
(0.37oC/10a), and; that of unused land, the lowest (0.28oC/10a). (5) The
degradation rates of permafrost in forested land (1.822×104 km2/10a)
and grassland (1.397×104 km2/10a) were the largest from 1980s to 2010s.