Significance and pedogenic variability of phytogenic mounds on the Loess Plateau of China

- Pedogenic variability of soil properties on phytogenic mounds were examined.
- Soil properties changed subtly between mound and intercanopy surfaces on α ≤ 46.6%.
- Soil samples in upper part of mounds showed higher quality on α > 46.6%.
- Soil nutrient and microbial activity were the key indicators affecting soil quality.
- Phytogenic mounds play an important role in preventing further soil deterioration.

Phytogenic mounds, a mound-type microtopography, always develop around plants as an interaction of individual plants with erosion, sedimentation, and bioturbation processes in many different ecosystems. In this study, the spatial variation of soil physical, chemical and biological properties was examined in different parts of phytogenic mounds and intercanopy surfaces on different slope gradients on the Loess Plateau of China. The key indicators that affect soil properties were identified. The results revealed that soil properties on mounds underwent a subtle change compared to intercanopy surfaces on α ≤ 46.6% slopes. However, an improvement of soil properties was observed on α > 46.6% slopes. The spatial variability of soil properties did not obviously change among different mound parts on α < 46.6% slopes. However, the soil indicators in the upper parts of the mounds increased by an average of 23.3% and 32.8% compared to the middle and lower parts, respectively, on α > 46.6% slopes. Soil chemical and biological variables were positively correlated. However, the physical properties correlated negatively with other variables. The soil available nutrient, moisture, and microbial activity were the key indicators that affected soil quality. The findings all indicate that phytogenic mounds play an important role in preventing soil deterioration and influence long-term ecosystem processes on the Loess Plateau of China.