Abstract: Based on field investigation and remote sensing, the spatiotemporal variations and primary influencing factors of net primary productivity (NPP) of new wetlands in the Yellow River Delta in recent 20 years were examined by using the CarnegieAmesStanford Approach (CASA). The correlation between observed and estimated NPP was significant (P<0.001), with averaged relative errors between -21.96 and 8.16. The NPP increased from coast to inland, and decreased from the banks along the river. The mean value of NPP and total NPP showed a downward trend from 1998 to 2016. The variation of mean NPP was relatively small, but the total NPP varied greatly, with the greatest total NPP occurring in 1998 and the smallest in 2010. The variation of NPP was obvious across seasons. The mean NPP was 74.25 g C·m^-2 in spring, 101.58 g C·m^-2 in summer, 41.83 g C·m^-2 in autumn, and 13.10 g C·m^-2 in winter. The estimated mean values of NPP differed with vegetation types. The estimated NPP values of various vegetations followed the Form. Robinia pseudoacacia > Form. Phragmites australis & Willow > crop > Form. Phragmites australis & Miscanthus saccharifleus & Imperatacy lindrica> Form.Phragmites australis & Tamarix chinensis> Form.Tamarix chinensis> Form. Suaeda heteroptera > Form. Spartana anglaca & Spartina alterniflora > Form.Tamarix chinensis & Suaeda heteropter a & Imperatacy lindrica. The correlation coefficient between NPP and soil soluble salt concentration was -0.389 (P<0.01). Therefore, reasonable “salt suppression with water” model can reduce soil salinity and promote the accumulation of plant organic matter.

Key words: Trichoderma longibrachiatum, Heterodera avenae, lethal and parasitic effects.