well you have not really described anything other than the word "salt marsh".
Based on only those descriptions I'd say a it's a marsh (swampy by nature, where crops should not be able to grow well, very wet. lots of insects trees should plentiful; although they'll be on the wild side, while being at the same time very strong. not many animals should be able to live there other than the crocodiles, alligators, anything amphibious by nature)
Oh and salt actually interferes with the growth of anything plant related. Which is why the Romans sowed salt into the soils of the Carthaginians after their defeat. To make sure they suffer for all eternity.
By the word salt. You can imagine it to be connected to the ocean, most likely than an actual salt deposit, becuase salt deposits are most often dry.
The combinations of the words "salt" and "marsh" would most likely lead me to believe that the the entire land is covered in deltas (much like the nile in Egypt, except imagine all of egypt to be interwoven like a spiderweb of deltas and not a desert)
So the person asking about the shrub land had questions to the properties of the trees in shrublands, But all you had was what a salt marsh is. Was there anything specific?