In conservation and biology in general there is a lot of talk over whether a species is native. This can often be quite a divisive issue because when species are not native they can often be removed or not be a part of policy making. This then means that when conservation plans are put into place a decision must be made as to whether a species is native or not.
So how do you decide whether something is in fact native?
A seemingly easy way of doing this is whether a species has been living in a location for a long time. However due to the wonderful nature of the world trying to pick a starting point in time and figure out what was living there can be a tricky task. For example certain plant species have always been in the UK such as Oak trees. They are therefore classed as native. Other plant species have been brought into the UK. This can happen for lots of different reasons whether its because the plant has a medical property that humans can use or it could be that they are just pretty. Many of these species have a specific few years when they were brought in. One example of this is Rhododendron ponticum which was brought in as an ornamental plant from Spain in 1763. Its since become an invasive species and out competes a lot of native species and such its regarded as a non-native species. However some research suggests that this species was growing in the UK before the last ice age. Obviously this was a long time ago but this does then pose the question of is it a native species as it once was many years a go.
It is a complicated question that I couldn’t answer in a simple blog post. However, most native species are defined as species that originated in their location naturally and without the involvement of human activity or intervention. This definition works for the majority of cases but should be called into question every once in a while!