In recent times, one should care about ecosystems and their protection. Countries spend very huge amounts of money for protection against so called invasive or alien species: species, that are not in their native range and are able to disperse in foreign lands without human help. Countries even spend much more money, trying to wipe out already established alien populations - often with little success. Usually, it is a fight against wind mills and management often only tries to keep the populations in check. They can be introduced by mistake as passenger in cargo or on car wheels or shoe soles. But often such species are introduced on purpose by people that think that they do something beneficial for nature or by introduction for example as an ornamental plant. From the gardens, the plants may disperse without human help. Not every alien species becomes an invasive one, but those having competitive advantages over native plants may be able to overcome native plants and become invasive. The more people grow such plants in their gardens, the easier it will be for the aliens to disperse in the wild. If an invasive species gains ground, it is hard to get rid of it again. Often, aliens have no enemies in their foreign range. Thus, they have a competition advantage over native plants and are able to overcome and displace the native flora. Additionally, the more alien species are present, the easier it gets for further aliens to settle - this is called invasional meltdown. Especially islands like Great Britain can be effected severely by invasive species, as those isolated ecosystems have a stronger limited pool of native species populations in comparison to main land ecosystems.
A working ecosystem is characterized by a high biodiversity, which means a lot of different species that compete against, but also facilitate each other. But all species have their own niche. Thus, no species is able to overcome the other completely. This is an attribute, that you can make use of for your own garden. If you turn your garden into a working ecosystem, it will reward you by a stable species community without heavy pest appearance and less weed that you have to fight against. Even the yield of crop plants will increase in many cases. Additionally, a stable ecosystem can be hardly occupied by aliens and provides habitat for many animals that may make your garden more enjoyable.
In the following posts, I will highlight some plants that you should avoid and plants on which you should keep an eye if you like to plant them in your garden. Thereby, I provide pictures that may help you to identify the plants, but I will resign to provide identification keys, as most plants are easy to see and to identify. Furthermore, I will recommend plants and habitat structures, that can be valuable agents that work for you and help to create a diverse biotope and a functional ecosystem.
