Table 2.

Area of different land-use types within the study area in 1990, 2000, 2010 and 2020 (Unit: km²).

Types	1990	2000	2010	2020
Cultivated land	200,737.28	205,969.87	197,542.58	200,865.00
Forest	38,732.68	35,327.35	37,620.32	38,139.89
Grassland	75,827.20	72,065.09	74,778.10	68,008.33
Water	6323.09	4957.00	5372.66	6049.30
Bare land	3390.27	3326.89	2999.11	2183.52
Construction land	7990.41	11,354.74	14,688.17	17,754.90