There are three main invasive species in the park, these are himalayan balsam, japanese knotweed and rhododendron.
Lots of volunteer time is spent each year working on the removal of these invasives.  By far the most time threatening and prolific of these plants is himalayan balsam.  Balsam is widespread along the river course, due to many hours weeks and years of work by all our groups and funding from The Forestry Commission it is now showing signs of being beaten.  You can read more about Himalayan balsam on if you follow this link.
There is another invader in the park, this one lives in Woodslee Pond.
American signal crayfish have been introduced into the pond at some point in the past.  These are very hardy and have a large apatite for our native pond life.  Alan the ranger has now got a licence to trap these creatures.