Marsh Fritillary Euphydryas aurinia- Impacts on populations include habitat degradation, parasitism, climate change, habitat neglect, resulting in prime habitats being fragmented and isolated (island effect) resulting in patchy distribution, this has caused several local extinctions across the range. So to summarize habitat loss and climate change are the key ones here.
Short-haired bumblebee
Bombus subterraneus- Possibly already extinct in the UK, Again habitat loss is a driving factor, reduction of favored flowering plants, intensive farming, pesticides. Also Climate change. Several British species are in danger too.
Norfolk Hawker dragonfly
Aeshna isosceles - Has never been a common British species, but has declined, this is more to do with pollution, land drainage and habitat loss than anything else, possibly global warming which would reduce optimum habitat. Not a fan of wet cool summers either. I also believe agro-chemicals are a serious negative factor affecting this species.
Hedgehogs - The obvious road vehicles but also cutting machinery also agro-chemicals, changes in farming practices, habitat destruction i.e hedgerows & fallow land, Garden chemicals.
Dormouse - presume you mean
Muscardinus avellanarius not
Glis glis, without doubt with this species it is habitat loss as it is depandant on ancient woodland. Due to this habitat being scattered it has caused population fragmentation with isolated islands with an isolated gene pool, inappropriate woodland management can contribute as a negative factor, reduction of hedgerows (act as corridors they wont cross open ground).
I dont know how much Wild-woman has said on this subject as it was in a PM, i know what i have wrote is very brief so if you require further detail on any of these species just ask, and ill be happy to help.
