Effects of natural and artificial restoration approaches on soil water-holding capacity in subalpine coniferous forests

Thousands of hectares of spruce plantations were established in the eastern Tibetan Plateau of China after the deforestation of primary conifer forests. However, the water-holding capacity of soils in these plantations remains unclear. Here, we investigated how soil water-holding capacity varied across a chronosequence of spruce plantations( 20 a, 30 a, 40 a, 70 a) in the western region of Sichuan Province and determined the differences between artificial forests( spruce plantations) and mixed broadleaf-conifer forests, which naturally developed on the cutovers. We further analyzed how the fine root biomass, litter stock, soil organic carbon, and soil physical structure affected soil water-holding capacity. Our results showed that across spruce plantations, the maximum water-holding capacity of 0-40 cm soil depth linearly, but not significantly, decreased with increasing stand age, from 2200 t/hm~2 in the 20-year-old spruce plantations to 2138 t/hm~2 in the 70-year-old spruce plantations, and the average annu