A three-dimentional model of the northeast East China Sea, with application to the M2 current field

A simple three-dimensional tidal model is used to examine the M2 tidal current distribution in a northeastern part of the East China Sea, especially the vertical variation of the current in the region. Computed M2 current is compared with observations available and found to be in good agreement.Main features of the calculating method in this study are: (1) Vertical variation of the tidal current is taken as a funetion of the depth-mean velocity: (2) the method is applicable to a variety of the vertical eddy viscosities; (3) it has a fine vertical resolution, especially near the sea bootom. So, this method not only enables us to get a steady state solution easily but also depicts effects of the friction on the vertical variation of the current much better.

Precipitation regulated soil nematode community and footprint in cropland ecosystems

●Nematode abundance and footprint show unimodal patterns with precipitation levels.●MAP governed nematode diversity along the precipitation gradient of agroecosystem.●Soil pH determined nematode abundance and footprint in low precipitation levels.Precipitation plays a crucial role in global biodiversity change across terrestrial ecosystems.Precipitation is proven to affect soil organism diversity in natural ecosystems.However,how precipitation change affects the function of the soil nematode community remains unclear in cropland ecosystems.Here,we tested soil nematode communities from different precipitation sites(300 mm to 900 mm)of the agricultural ecosystem.The abundance of total nematodes,fungivores,and plant parasites,together with the footprint of fungivores was significantly affected by mean annual precipitation(MAP)in cropland ecosystem.Plant parasites diversity and footprint showed negative relationships with MAP.The random forest suggested plant parasite footprint was the most responsive to MAP.The structural equation model revealed that MAP affected nematode abundance and footprint indirectly via soil pH;nematode diversity was affected by MAP directly.We conclude that precipitation could act as the main selection stress for nematode diversity among the large gradient of agricultural ecosystems.However,the soil pH may act as a stress factor in determining nematode community and carbon flow in the soil food web.Our study emphasized that using nematode value by trophic group would provide a deep understanding of nematode response to precipitation in cropland ecosystems.