Using state and trend analysis to assess ecological security for the vulnerable agricultural ecosystems of Pengyang County in the loess hilly region of China

Figures & data

Figure 1. Location and terrain of the study area.

Figure 2. Adapted pressure–state–response framework for regional ecosystem assessment of ecological security.

The index system and thresholds for land ecological security in the loess hilly region

Objective level (A)	Factor level (B)	Indicator level (C)	Weight (w)	Threshold value (Z)
Ecosystem pressure A1	Population B1	Population density (/km^2) C1	0.042	100
		Population growth rate (‰) C2	0.032	6
		Arable land per capita (hm^2per capita) C3	0.037	0.3
	Environment B2	Chemical fertilizer per unit arable land area (kg/hm^2) C4	0.010	300
		Pesticide per unit arable land (kg/hm^2) C5	0.010	30
		Topology C6	0.037	0.3
		Percentage of natural disaster area (%) C7	0.037	10
Ecosystem state A2	Soil quality B3	Grain production per unit area (kg/hm^2) C8	0.051	2500
		Soil erosion modulus (t/km^2 a) C9	0.109	1000
		Percentage area for soil and water loss (%) C10	0.097	15
	Land-use structure B4	Forest cover rate (%) C11	0.108	39
		Percentage area for slope cropland over 25° (%) C12	0.090	1
Human response A3	Action to reduce effect, Improvement B5	Effective irrigated area rate (%) C13	0.085	30
		Invest in environmental management to GDP (%) C14	0.102	1.4
		Income of tertiary sectors to GDP (%) C15	0.068	30
		Net income per capita (Yuan) C16	0.085	2000

Figure 3. State and trend of regional land eco-security.

Figure 4. Status of eco-security indices in 2004.