Effects of topography and land-use patterns on the spatial heterogeneity of terracette landscapes in the Loess Plateau, China

Abstract Terracette landscapes are common on hilly rangelands in arid and semiarid regions. Terracette structure significantly modifies the hydrological and biogeochemical processes, resulting in striking spatial patterns in soil moisture, nutrient, and vegetation distribution. However, there is still no efficient and precise method for monitoring and analyzing terracettes formation and maintenance processes. Therefore, we investigated spatial patterns and vegetation cover of these landscapes via field sampling and unmanned aerial vehicle (UAV) methods on the Loess Plateau, China. The parameters considered included land-use patterns (grazed vs. un-grazed) and topography (aspect: north and south, slope: 0°, 15°, 30°, and 45°). We revealed structural characteristics of terracettes, evaluated the differences between two sampling methods and explored the potential formation and maintenance mechanisms of these landscapes. The results showed that: 1) terracettes only existed in the north-30°, north-45°, and south-45° areas of grazed plots, 2) terracettes density (terracettes basic unit number/m, TBU/m) and vegetation cover differed significantly among the land-use patterns and topographies, 3) vegetation cover increased and then decreased with increasing terracettes density, with an inflection point of ~0.78 TBU/m, up to a vegetation cover of ~70%. These results could have major implications on land-use policies and environmental conservation and socioecological sustainability practices of the Loess Plateau. Finally, UAV can be used to effectively and accurately monitor and analyze terracette landscapes, and have great potential for monitoring terracettes in future studies.