3. Results

with different biomes and assigned based on the results derived by Xie et al. [31], who had estimated the equivalent weight factors and modified the ESV coefficient per hectare of terrestrial ecosystems in China. To quantitatively assess the impact of land with different desertification degrees on the regional ESV, the ESV for the low, medium, high, and severely desertified lands was assigned by the use of the equal interval grading weight factor between the ESV of

ESV <sup>¼</sup> <sup>X</sup><sup>n</sup>

where ESV is the total ecosystem service value of one region (10,000 yuan�km�<sup>2</sup>

adjusted ESV per unit area of land use and land cover type <sup>i</sup> (10,000 yuan�km�<sup>2</sup>

because the ESV always has a robust positive relationship with the biomass [41]:

�a�<sup>1</sup>

i¼1

). We took into consideration the differences in the ESV provided by the same type of land use and land cover in different regions and introduced an adjusting factor in this study by biomass

where Bj is the biomass of the land use and land cover type i, which was replaced by the NDVI in this study. B is the average biomass of the land use and land cover type i in China, which was also calculated by NDVI; and Pi is basically the ESV per unit area of land use and land

In this study, the sensitivity coefficient was conducted to assess the changing degrees of the regional ESV that was caused by desertification. The sensitivity coefficient (SAF) measured the sensitivity degree by comparing the changes in the ESV of the whole region to the deserts and

SAF <sup>¼</sup> VC<sup>0</sup> ð Þ � VC <sup>=</sup>VC

where SAF is the sensitivity coefficient and higher values of ∣SAF∣ indicate greater changes in the regional ESV caused by desertification; VC<sup>0</sup> is the regional ESV in 2010; VC is the regional ESV in 1981; S<sup>0</sup> is the ESV of the deserts and desertified lands in 2010; and S is the ESV of the

> Medium desertification

Total 126.29 35.48 203.67 47.17 39.31 26.21 18.34 6.24

Pij � Ai (1)

Pij <sup>¼</sup> bj=<sup>B</sup> � �Pi (2)

<sup>S</sup><sup>0</sup> ð Þ � <sup>S</sup> <sup>=</sup><sup>S</sup> (3)

Severe desertification

/a).

Desert

High desertification

), which is shown in Table 1.

�a�<sup>1</sup>

�a�<sup>1</sup>

), Pij is the

), and Aij is

the deserts and undegraded grassland:

16 Community and Global Ecology of Deserts

the area of land use and land cover type i (km<sup>2</sup>

cover type <sup>i</sup> in China (10,000 yuan�km�<sup>2</sup>

desertified land from 1981 to 2010:

deserts and desertified lands in 1981.

areas

Low desertification

Table 1. The ESV per unit area of different land types in Inner Mongolia (million yuan/km<sup>2</sup>

Forest Farmland Water

2.3.3. Sensitivity analysis
