TY  - JOUR
T1  - The role of topography in shaping the spatial patterns of soil organic carbon
AU  - Zhu, Meng
AU  - Feng, Qi
AU  - Qin, Yanyan
AU  - Cao, Jianjun
AU  - Zhang, Mengxu
AU  - Liu, Wei
AU  - Deo, Ravinesh C.
AU  - Zhang, Chengqi
AU  - Li, Ruolin
AU  - Li, Baofeng
JO  - CATENA
VL  - 176
SP  - 296
EP  - 305
PY  - 2019
DA  - 2019/05/01/
SN  - 0341-8162
DO  - https://doi.org/10.1016/j.catena.2019.01.029
UR  - https://www.sciencedirect.com/science/article/pii/S0341816219300293
KW  - Soil organic carbon
KW  - Elevation
KW  - Aspect
KW  - Vegetation type
KW  - Structural equation modelling
AB  - In regions with a relatively complex topography, the soil organic carbon (SOC) is characterized by a high spatial heterogeneity, which is likely to contribute to large uncertainties in the regional SOC estimation. Generally, the elevation and aspect are expected to be the two main topographic controls of the spatial patterns of SOC on steep hillslopes. However, the manner in which the aspect-induced variability in SOC varies with elevation zone is still less understood. In this study, SOC in three elevation-dependent vegetation zones (~2450 m: the shrub-steppe zone, ~2900 m: the forest-steppe zone, and ~3350 m: the shrub-meadow zone) was examined in the Qilian Mountains. Soil samples at 0–10, 10–20, 20–40, and 40–60 cm were collected on the south-, southwest-, west-, northwest-, and north-facing slopes with similar slope gradients (~32°) in each of the three vegetation zones. The results showed that the SOC density tends to increase following the elevation zone, with an average density of about 24.30 kg m−2 at the 0–60 cm. In addition, the SOC concentration appeared to have increased with the cosine of the aspect following an exponential function. The average rate of increase in terms of the aspect at 0–10 cm in the forest-steppe zone was approximately 0.46 g kg−1 degree−1, which amounted to 1.39 and 2.19 fold greater than in the shrub-steppe and shrub-meadow zones, respectively. Path analysis performed using structural equation modelling (SEM) demonstrated that the elevation and the aspect had an indirect influence on the SOC density, through a direct effect on the soil temperature, vegetation type, and soil moisture, and this could possibly explain 88% of the total variation in the SOC density. The present results suggest that the forest-steppe zone is characterized by the strongest aspect effect on SOC in comparison with the shrub-steppe and shrub-meadow zones, and confirm the importance of elevation and aspect in shaping the spatial patterns of SOC.
ER  -