Shirong Zhang
https://orcid.org/0000-0002-1895-2494
Abstract: Soil phosphorus (P) is an essential nutrient that
controls wetland productivity and ecological functions. However, the
effects of soil P forms on P availability during wetland degradation are
relatively unknown. Soil samples from differently degraded marshes,
including relatively pristine marsh (RPM), lightly degraded marsh (LDM),
moderately degraded marsh (MDM), and heavily degraded marsh (HDM), were
collected to investigate the
changes in soil P forms and its regulation on P availability in the
Zoige Plateau, China. We observed that compared with RPM, the main
changes in total P concentration were a significant increase of
31.6%–44.2% in the 0–30 cm soil layers of LDM and MDM, and the
available P concentration increased in LDM and MDM but decreased in HDM
with a lower P activation coefficient. Marsh degradation increased the
concentration and proportion of dicalcium phosphates, P occluded in iron
hydroxides, and organic P but decreased those of iron oxide surfaces
adsorbed P and apatite P. Soil
available P was mainly related to organic P and P non-occluded in iron
oxide minerals that might also be non-negligible direct source of
available P. The transformation from apatite P to organic P was an
important regulation mechanism of P availability in soils during marsh
degradation. This study revealed the risk of P limitation in heavily
degraded marsh soils and
established the mechanism by which
marsh degradation significantly influences soil P availability.
Therefore, some measure of on improving P availability should be
implement for the ecological restoration of heavily degraded marsh in
the future, such as grazing exclusion and the application of organic
fertiliser.
Keywords: Zoige Plateau; Marsh degradation; Phosphorus forms;
Phosphorus transformation; Phosphorus availability