Changes of sulfur fractions in sediment following Spartina alterniflora invasion in a seaward direction in a temperate salt marsh, China

Abstract

With immense impact on coastal ecosystems' function, especially on nutrient cycle, Spartina alterniflora has become the most importantly invasive species in coastal wetland of China. However, the alternation of sulfur level and transformation between different inorganic sulfur (IS) fractions caused by the plant are poorly understood. In order to study the effect of S. alterniflora invasion and growth on soil IS components, we used space-for-time substitution method and examined a whole year dynamics of different sulfur components in 0–60 cm soil of S. alterniflora tidal flat and mudflat at Jiaozhou Bay. Results indicated S. alterniflora improved soil sulfur level and its bio-availability, increased the contents of soil TS, total inorganic sulfur (TIS) and all of the IS fractions except hydrochloric acid volatile sulfur (HVS). But only the rate of soil adsorbed sulfur (AS) to TIS raised following invasion. In addition, S. alterniflora elevated the accumulation sites of soil Hydrochloric acid soluble sulfur (HSS) and HVS from deep soil to rhizosphere in spring. Key impact factors on IS fractions altered as invasion from soil physicochemical factors to plant fctors. Further, S. alterniflora encouraged the transformation of sulfur state from precipitation (HSS, HVS) to dissolved (HS, AS). This implies that the plant induced to an elevation of sulfur provided capacity and a reduction of sulfur toxicity in soil, which has vitally ecological significance for its expansion in costal wetlands. Now, S. alterniflora has occupied large area mudflat and was competing for habitat with native species in Jiaozhou Bay.