How to connect sensors to Mangoh green

How to connect multiple sensors to mangoh green board directly? Is there any way we can connect sensors using I2C interface? or
Do we need arduino shield only to connect sensors on mangoh green?

I2C is available on the IoT expansion sockets.

Beware of the voltage levels!

Take a look at: https://mangoh.io/iot-cards

and: https://mangoh.io/buy-iot-cards - in particular, the Renfell I2C SPI GPIO UART IoT Card: https://mangoh.io/uploaded-documents/Buy/IoT%20Cards/Renfell/0107-10-R1.1-Interface-20161201.pdf