3-D soil macropore networks derived from X-ray tomography in an alpine meadow disturbed by plateau pikas in the Qinghai Lake watershed, north-eastern Qinghai-Tibetan Plateau

Abstract

The plateau pika (Ochotona curzoniae) is one of the main native soil faunas on the Qinghai-Tibet Plateau and plays a key role in the terrestrial ecosystem there. However, few studies have analysed the macroporosity of soils disturbed by plateau pikas in alpine meadows. The objective of this study was to examine the soil macropores in different parts of an alpine meadow in the Qinghai Lake watershed, namely, an original grassland, a new mound, an old mound, and a bald patch. In this investigation, soil cores were obtained from four different parts of an alpine meadow, namely, from under an original grassland, a new mound, an old mound, and a bald patch. A total of twelve soil cores (0–50 cm deep) were excavated, which included three replicates of each treatment. The soil architecture of each soil core was explored using X-ray computed tomography. The macroporosity decreased and then increased from the original grassland to the new mound, old mound, and bald patch. The soil macropores were most abundant up to a depth of 400 mm in the original grassland and up to a depth of 250 mm in the old mound and bald patch soils. The macropores in the original grassland were attributed to well-developed root systems. The smaller and less continuous macropores in the new mound, old mound, and bald patch soils were mainly disturbed by plateau pikas. It was expected that water would move preferentially through the macropores in the original grassland, while surface flow would more readily occur in the new mound, old mound, and bald patch soils, thereby leading to soil erosion.