Abstract
Root hemiparasitic Pedicularis kansuensis is an invasive native species
in China and has been expanding in the Bayanbulak Grassland of Xinjiang
Uygur Autonomous Region over the past decade, threatening the local
livestock industry. To understand why this damaging species expands in
some areas but not in others, we compared soil water content, soil
nutrient status, and plant community structures between heavily infected
and non-infected sites. We hypothesized that soil nutrient levels and
plant species composition would be more beneficial to the spatial
expansion of P. kansuensis in heavily infected areas than in
non-infected ones. Quadrat (1 m × 1 m) surveys were carried out in the
Bayanbulak Grassland. Species number, percent vegetation cover,
aboveground plant biomass, plant height, and relative frequency were
recorded. Three topsoil samples were taken at 0–10 cm depth from each
quadrat and their nutrient statuses were determined. The results showed
that (1) P. kansuensis invasion reduces the species richness of the
community compared to the uninvaded area (3.07%), but increases the
canopy cover overall (16.99%); (2) soil water content (SW) and soil
nutrient content are the main factors that determine invasion by P.
kansuensis, and SW plays the more important role; (3) SW controls P.
kansuensis leaf stoichiometry, decreases the Ratio of leaf nitrogen (LN)
to leaf phosphorus (LP), and affects LP (P < 0.005). Finally,
after combining the results, we found that the soil factor accounted for
46.50% and plants accounted for 22.50% of P. kansuensis invasions in
the Bayanbulak Grassland.