Native or Non Native ?
Something I have been puzzling over recently and wondered if anyone had any thoughts on this subject ?
Is there actually a time limit on when a plant species can be classed as a Native or non Native ? Hundreds, thousands or millions of years ?
Is there any difference between species introduced by man or introduced by other , say more natural, means ? Well, yes there is a difference obviously but at what point in time do you draw a line ?
We are all aware of Rhodos, Himalayan balsam, Japanese Knot weed ,Grey Squirrels, Mink and many others but is the classic English Oak or the Horse Chestnut deemed to be native and by what criteria ?.
In other words, would you say that anything introduced to the UK after 1500 is non native or would you draw the line at anything introduced after 1800 ? Or pick any date before, in between or after.