Today, time and time again, we're hearing stories of species on the move. Climate change and the great flow of human traffic around the globe means that species once isolated, are now springing up in the most unexpected places. And this mixing up of the world's species is starting to have significant consequences. More than 40% of Britain's wild plants are exotic species, introduced by us humans over the last thousand years. That's sumac, not native. Not native. That's not native, that's not native. What's that? That's Sycamore, that's not native. Yeah. I've come to London's urban jungle with museum botanist Mark Spencer. We're on the hunt for a new generation of exotic plants that are about to change the face of the British landscape. This here is the Loquat tree which is thought native to this country. It's actually a plant from East Asia, China, Japan. It's been grown in that part of the world for centuries. And this plant itself has actually really just been grown as an ornamental in this country for about 200 years, and never produced fruit because for many years our climate just wasn't warm enough. So what's different, what's going on now, then? It's just beginning to be able to, really, in the last ten years or so produce a lot of fruit. So for example in 2003, the really hot summer we had, I saw trees in people's gardens in London with hundreds and hundreds of fruit.


今天，一次又一次地，我们听到物种迁移的消息，气候变化和全球大规模交通，使得曾经只在特定地区生存的生物。在出人意料的地方大肆繁衍，被打乱的世界物种分布，正在引发严峻后果。英国超过百分之四十的野生植物，是在过去一千年内人为引进的。 那是漆树，非本土物种，非本土物种，这也不是，那个也不是。 -那是什么 -美国梧桐，非本土的。 我和博物馆生物学家马克·斯宾塞一同来到伦敦城市森林寻找即将改变英国自然风光的新一代外来植物 这是一棵枇杷树，它不是我国本土的植物。它来自东亚国家，比如中国和日本，这种树在东亚生长了数世纪，于大约两百年前被引进到英国。作为观赏植物种植，两百年来从未结实，因为那时英国气候不够温暖。 那么现在有什么变化呢？ 从大约十年前开始，英国的枇杷树开始结出果实。例如在2003年，那个非常炎热的夏天，我看到伦敦市民花圃里的枇杷树结了成百上千的果实。