The effects of different land use patterns on the microclimate and ecosystem services in the agro-pastoral ecotone of Northern China

The land use structure is extremely unstable and grassland is reclaimed as cultivated land at a large scale in the Northern Foot of Yinshan-Otindag Sandy Land Windbreak and Sand-Fixation Ecological Conservation Area, a representative region of the agro-pastoral ecotone of Northern China. To study the effects of land use patterns on the microclimate and ecosystem services, we selected five land use patterns by using a grid cell approach: pattern 1 (6.35% of the cultivated land, 86.98% of the grassland), pattern 2 (20.66% of the cultivated land, 71.14% of the grassland), pattern 3 (47.02% of the cultivated land, 44.76% of the grassland), pattern 4 (58.65% of the cultivated land, 31.49% of the grassland), and pattern 5 (70.55% of the cultivated land, 18.04% of the grassland) in 2010-2015. The results were as follows: (1) compared with pattern 1, the other four patterns had higher evapotranspiration (ET) and lower land surface temperature (LST), but no significant differences in albedo; (2) based on the partial correlation analysis, ET was the key driving factor in response to energy budget, and the global sensitivity analysis showed that LST had a strong independent influence on the ET, while LST, normalized differential vegetation index (NDVI), and albedo had strong interaction effects on the ET; (3) from June to August, the relationship between the proportion of cultivated land and ET was a logistic curve, and the inflection point was respectively 16.76%, 22.27% and 19.50%, respectively; (4) the losses of ecosystem service values (ESVs) had a significant trend in the whole ecological conservation area, and for five land use patterns, the order of losses was pattern 5 > pattern 4 > pattern 3 > pattern 2 > pattern 1; (5) pattern 5 lost the most ESVs, mainly due to three types of ecosystem services, which were soil conservation, climate regulation and waste regulation. This study provides references for fully understanding the ecological effects of land use change and helps to objectively evaluate ecological civilization construction in the agro-pastoral ecotone of Northern China.