Labile and Recalcitrant Soil Carbon and Nitrogen Pools in Tidal Salt Marshes of the Eastern Chinese Coast as Affected by Short‐Term C₄ Plant Spartina alterniflora Invasion

Abstract

Terrestrial ecosystems carbon (C) and nitrogen (N) cycles, affected by plant invasion, are not fully understood. In this study, the impact of 10 years Spartina alterniflora invasion on soil organic matter (SOM), labile, and recalcitrant pools was examined comparing with bare flat and native Suaeda salsa and Phragmites australis communities in tidal salt marshes of the Eastern Chinese coast. Short‐term S. alterniflora invasion significantly raised C and N concentrations in SOM, labile and recalcitrant pools compared to bare flat, S. salsa and P. australis soils. Spartina alterniflora soil had higher recalcitrant index for C relative to bare flat. The proportion of S. alterniflora‐derived C and the decomposition rate of old C in the labile pool were significantly higher than those in the recalcitrant pool. However, the S. alterniflora‐derived C stock of the recalcitrant pool was much greater than that of the labile pool. The SOM and recalcitrant pools in S. alterniflora soil had significantly higher δ15N levels compared with bare flat, indicating an increased N loss following S. alterniflora invasion. The results suggested that short‐term S. alterniflora invasion significantly enlarged soil organic C and N pools via altering SOM input and decomposition.

Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China

“…Our findings not only added to various evidence that S. alterniflora invasion greatly accelerated soil organic C and N accumulation due to greater biomass input1429 (Table 1), but also found that S. alterniflora invasion significantly increased MBC concentration and the quantities of the total and all types of PLFAs compared with bare flat soil (Figs 1, 2, 3). Soil C sources are considered as crucial ecological driving factors for microbial community dynamics32.…”

“…Previous studies have reported that S. alterniflora has a longer growing season, a higher leaf area index and net photosynthetic rate, and a greater net primary production compared with the native plants, Scirpus mariqueter and P. australis 31. Furthermore, S. alterniflora invasion significantly alters soil physicochemical properties16, soil organic C and N sequestration1429, and emissions of greenhouse gases in the coastal wetland of eastern China20. However, little is known about the changes in the soil microbial community structure and activity in chronosequences following S. alterniflora invasion.…”

“…Previous studies have found that plant invasion can change aboveground (leaf litter) and belowground (root litter and exudates) inputs1314. Elgersma et al 8.…”

“…Plant invasion also shifts the resources available to soil microorganisms and further changes the soil microbial community15. Many invasive plants are considered to be more decay resistant owing to their higher levels of lignins, tannins, and other secondary compounds12, and lower quality of invasive plant materials (higher carbon (C)/nitrogen (N) ratio of litter and/or root)14. These invasive plants are ultimately the cause of higher soil C:N ratios relative to the native ecosystem16.…”

Effects of reclamation on heavy metal pollution in a coastal wetland reserve

“…was founded in 1983, and is one of the best-preserved natural salt marshes in China (Yang et al 2013;Zhou et al 2009). It was recognized as a part of the UNESCO World Network of Biosphere Reserves in 1992 and is critical to China's biodiversity conservation (Yang et al 2015). In the reserve, which has a dyke built outside the core area along with a drainage system and freshwater irrigation applied inside, reclamation has been conducted for about two decades, which so far has resulted in more than 50 % of the whole reserve becoming reclamation habitats.…”