Referring to the BTCV manual on planting in wet ground :-
Alder --Can survive anerobic (stagnant) soil conditions
Downy Birch
Hornbeam --Will well on sites that are seasonally wet.
Oak Pendunculate--Will well on sites that are seasonally wet.
Oak Sessile
Poplar Black-- will only tolerate wet ground if there is water movement within the soil
Willow crack--Can survive anerobic (stagnant) soil conditions
Willow White--Can survive anerobic (stagnant) soil conditions
I would have thought that under natural conditions several of these species would have already colonised this site. Their absence may well be due to previous human intervention.