Impacts of land conversion and management measures on net primary productivity in semi-arid grassland

Figures & data

Figure 1. Location of the Xilingol grassland (a). Elevation of the Xilingol grassland and distributions of the field verification sites (b); Distribution of meteorological stations, annual precipitation, and its vegetation types (c). DW, Dongwuzhumuqin Banner; XW, Xiwuzhumuqin Banner; XL, Xilinhot; AB, Abaga Banner; SZ, Sunitezuo Banner; SY, Suniteyou Banner; EL, Erlianhot; XH, Xianghuang Banner; ZXB, Zhengxiangbai Banner; ZL, Zhenglan Banner; DL, Duolun

Figure 2. Correlation between estimated NPP and observed NPP in Xilingol grassland in July 2014

Figure 3. Processing flows for distinguishing the contribution of land conversion, grazing management, and climate variation to changes in NPP

Table 1. Area of land use change in Xilingol from 2000 to 2015. (unit: km²)

	Woodland	Grassland	Water bodies	developed land	Desert land	Wetland	Bare land	Cropland
Area in 2000	3248.45	169,741.83	1780.40	680.90	7651.58	5708.82	6554.84	5841.28
Area in 2015	3277.71	169,207.41	1427.48	1280.04	8119.06	5510.30	6714.92	5671.18
Area change	29.26	−534.42	−352.92	599.14	467.48	−198.52	160.08	−170.10
Change rate (%)	0.90	−0.31	−19.82	87.99	6.11	−3.48	2.44	−2.91

Figure 4. Spatial distribution of gains and losses in the Xilingol grassland between 2000 and 2015

Table 2. Gains and losses in the Xilingol grassland from 2000 to 2015

	Code	12	32	42	52	62	72	82	Sum
Grassland gains	Area (km^2)	34.82	82.45	3.94	811.02	176.73	184.38	365.56	1,658.91
	Percentage (%)	2.09	4.97	0.23	48.89	10.65	11.11	22.04	100.00
	Code	21	23	24	25	26	27	28	Sum
Grassland Losses	Area (km^2)	65.34	65.62	524.84	934.16	34.76	348.03	220.58	2,193.33
	Percentage (%)	2.97	2.99	23.93	42.59	1.58	15.87	10.05	100.00

Note: Grassland gains denote the regions with other land types in 2000, but converted to grassland in 2015. 12: woodland to grassland; 32: waterbodies to grassland; 42: developed to grassland; 52: desert land to grassland; 62: wetland to grassland; 72: bare land to grassland; 82: cropland to grassland. Grassland losses indicate areas where there was grassland in 2000 but were later converted to other land types. The opposite codes represent the opposite land conversion.

Figure 5. (a) Spatial distribution of coverage change in unchanged grassland from 2000 to 2015 and (b) coverage change in eleven administrative sub-regions

Figure 6. (a) Inter-annual variations in annual average actual NPP and climate-induced NPP in the Xilingol grassland from 2000 to 2015; (b) Actual NPP change of Xilingol grassland between 2000 and 2015

Table 3. NPP changes caused by different forms of grassland conversion between 2000 and 2015

2000 NPP			2015 NPP
Grassland losses	Mean NPP (g C·m^−2·yr^−1)	Total NPP (Gg C·yr^−1)	Grassland gains	Mean NPP (g C·m^−2·yr^−1)	Total NPP (Gg C·yr^−1)
21	219.96	14.37	12	380.53	13.25
23	153.24	10.05	32	161.00	13.27
24	186.73	98.00	42	138.42	0.54
25	129.82	121.27	52	196.28	159.19
26	157.70	5.48	62	379.05	66.99
27	116.68	75.16	72	150.63	27.77
28	228.54	50.41	82	340.03	124.30
Sum	155.10	340.20		244.33	405.32
Unchanged	177.86	29,789.13	Unchanged	225.30	37,734.68
Sum_2000		30,129.33	Sum_2015		38,139.99

Figure 7. The contribution of land conversion to total NPP changes in the sub-regions between 2000 and 2015

Table 4. Quantitative analysis of the contributions of climate variation and human activities to NPP changes in the Xilingol grassland between 2000 and 2015

	ΔNPP	NPPcli	NPPhuman		NPPcli %	NPPhuman %
			NPPlc	NPPma
XL	1,478.87	430.72	−32.83	1080.97	29.12	70.87
AB	1,106.84	43.22	−7.86	1,071.48	3.90	96.09
SZ	−167.89	−237.09	8.48	60.72	−141.22	41.22
SY	−213.24	−273.72	−18.23	78.71	−128.36	28.36
DW	3,339.26	461.29	30.45	2,847.51	13.81	86.19
XW	1,767.37	646.62	8.33	1,112.42	36.58	63.42
TP	63.59	7.43	7.66	48.49	11.69	88.31
XH	−260.78	−275.52	−4.10	18.85	−105.65	5.65
ZXB	−66.95	−84.73	−57.97	75.75	−126.55	26.55
ZL	550.83	263.22	66.20	221.40	47.79	52.21
DL	412.85	173.67	45.59	193.59	42.07	57.93
XLG	8,010.73	1155.61	45.72	6809.40	14.42	85.58

Note: NPP_{_human} includes the NPP changes induced by grassland conversion and by management measures in the unaltered grassland. NPP induced by climate change included the NPP changes induced by climate change in the newly added and unchanged grassland.

Figure 8. (a) Spatial distribution of NPP changes induced by climate variation, (b) land conversion and (c) management measures in the Xilingol grassland between 2000 and 2015 (Unit: g C·m⁻²·yr⁻¹)

Figure 9. Spatial changes in precipitation and temperature in Xilingol grassland from 2000 to 2015

Figure 10. Changes of urbanization, road construction (a) and coal production (b) in Xilingol from 2000 to 2015

Figure 11. (a) Spatial pattern of the livestock number trends in the Xilingol grassland from 2000 to 2015, (b) Spatial pattern of livestock sheds and corrals; Inter-annual variation in livestock structure (c) and fenced grassland area (d)