Pattern of soil extracellular enzyme activities along a tidal wetland with mosaic vegetation distributions in Chongming Island, China.

Soil extracellular enzymes play an important role in the biochemical cycling in the coastal tidal wetland. Previous results revealed the factors affecting the soil extracellular enzyme activity (EEA) in the terrestrial ecosystems with acid soils, while it is still unknown what factors mainly affect the EEAs in the tidal wetland with neutral or alkaline soils. To reveal the factors affecting the variations of soil EEAs along the tidal wetland with mosaic distributions of vegetation types, the activities of nine types of soil enzymes, whose functions closely related to the cycling of soil C, N and P, respectively, were investigated in the Chongming Dongtan tidal wetland, East China. The soil samples with different layers were collected from the unvegetated area (S1), Spartina alterniflora area (S2), Scirpus mariqueter area (S3), and Phragmites australis area (S4), respectively, over the high tidal zone (HT), mid-tidal zone (MT) and low tidal zone (LT), respectively. The results showed that the soil EEA profiles were observably (p < 0.05) among the vegetation types, soil layers and tidal levels, based on the multi-response permutation procedure (MRPP) method. Variation partitioning analysis revealed that soil properties, soil layer, tidal level and vegetation type explained 28.2% variation of EEAs. Soil properties explained 17.5% variation of EEAs. The most variations of EEAs explained by soil layer, tidal level and vegetation type were soil characteristics, and 3.6% variations of EEAs were explained by the others three variables. NH 3 –N, C/N and BD were the most important factors affecting the variations of EEAs. Therefore, the most variations of EEAs were well explained by the soil properties in the Dongtan tidal wetland, East China. [ABSTRACT FROM AUTHOR]