Potentilla fruticosa has a greater capacity to translocate phosphorus from the lower to upper soils than herbaceous grasses in an alpine meadow

Abstract

Potentilla fruticosa is widely distributed in the Northern hemisphere; however, its effect on soil properties in the ecosystems is unknown. We examined the effects of P. fruticosa (a key shrub in the system) on soil organic carbon (SOC) and nutrient accumulation patterns in an alpine meadow on the Qinghai–Tibetan Plateau. In a flat area (about 1200×400m), we extensively sampled aboveground and belowground biomasses, litter accumulation and soils in P. fruticosa and herbaceous plant patches. We also intensively sampled soils down to 1m depth along a 24-m transect that crossed through alternating P. fruticosa and herbaceous plant patches. The aboveground biomass, litter accumulation and root biomass down to 0.5m depth were all significantly greater under P. fruticosa than herbaceous plants. SOC, total nitrogen (N) and phosphorus (P) across 0–0.1, 0.1–0.2 and 0.2–0.3m soil layers were 12%, 17% and 9% greater, respectively, under the P. fruticosa than herbaceous plants. Soil N and P availability in the upper layers was also greater under P. fruticosa than under the herbaceous plants. The intensive sampling revealed that the increases in SOC and total N below P. fruticosa, relative to the herbaceous plant patches, occurred down to 0.8m depth. However, the higher total P concentrations in the upper soils under P. fruticosa occurred at the expense of lower levels of P in the deeper soil layers. Along the 24-m transect, SOC, total N and inorganic N storage in the 1m soil depth increased when P. fruticosa was present; however, total and available P storage fluctuated in the opposite pattern, decreasing when P. fruticosa was present. This indicated that during the succession of the community, greater SOC and N accumulation versus a depletion in P in the top 1-m soil layer occurred under P. fruticosa, compared to under the herbaceous plants. We concluded that there was heterogeneity in the soil nutrient resources that was associated with P. fruticosa patches in the alpine meadows. P. fruticosa had a greater capacity to translocate P from the lower to the upper soils than the herbaceous plants.