Create an Ecological Garden
Lifehack
I already mentioned earlier, that you can benefit by an ecological garden. A high biodiversity is a key factor to maintain ecosystems and their functions, as well as protecting them from invasion by foreign species. A high biodiversity also helps in growing crop plants, as well as helping to keep pests under control.
Now, I would like to present you some ideas, what you can do to create variable structure to provide habitat to a lot of diverse organisms (animals, plants and even fungi).
Wild flowers
Today, most fields and areas are cultivated and too often, insects are killed by insecticides. Additionally, herbs and flowers are killed by herbicides as well. Wild flowers are an important food source for many insects like honey bees, wild bees, bumblebees and butterflies. In turn, those are an important food source for insect feeding animals. In this regard, the goldfinch is especially important as well as bats. Recently, many of these animals are more or less strongly endangered.
A few square meter of wild flowers can provide already a rich food source and a good habitat for a whole bunch of animals and ensure the survival of those animals. Furthermore, many of these animals are useful assistants to fight against pest, like louse, bugs and mosquitoes. Especially lady bugs and lacewings are attracted by wild flowers and love to feed on your louses that may infested your crops or flowerpots. The flowers should be cut only once a year in late autumn, after all seeds are dispersed. To protect the animals, living there, you should not cut too deep above the ground or (more beneficial) leave some areas completely uncut.
If you don't have wild flowers occurring naturally in your garden, you can buy seeds and grow them by yourself. But you should carefully choose the seeds or seed package as many companies mix the wild flowers just by their visual appearance. Often you get non-native flower species or even invasive species that may counteract your efforts. You can buy seed mixtures that contain native (to UK) flower species for example at wildflower.co.uk.
If you prefer to mix the seeds yourself or have other sources, there are a lot of sources in the internet, where to buy mixtures or separate flower seeds (for Germany, I can recommend Saatkontor.de or bingenheimer Saatgut). You can also find a lot of articles, that provide ideas for native flowers, like countrylife.co.uk and many others.
Herb mountain
For all herb lovers and hobby gardeners a must have: a nice herb garden. There are many herbs with very different needs. To provide space and suitable habitat for many different herbs you can build a small herb mountain. Therefore you should create several level. A borderline with bigger natural stones between the level would be especially appropriate (like foundlings or rubblestones). Those can be stratified along each level border. The substrate for each level should be capable to hold more and more water from the top to bottom. You can achieve this by mixing stones and sand with regular soil at higher level and more regular soil for lower level. At the bottom you can seal the ground with a thin layer of clay containing soil in a small cavity to achieve a very moist foot of this mountain (but make sure that water can still drain off).
Now, you can grow Mediterranean herbs like thyme, rosemary, oregano, etc. on the top level. Additional, flat stones on the top level may increase drought and heat on this level. On the intermediate level you can grow sub-Mediterranean herbs like parsley, sage or dill. At the lowest level you can grow herbs that like high moisture or swampy soil like chives and basil. You should ensure to have clear steps between the different level that the water can drown off to deeper level and not to swell on too flat level. You may will observe some lizards and other hot stone loving animals that crawl through your herb garden if you have some nice stony places that heat during the day. Additionally, the wholes between the stones serves as accommodation for lizards, wild bees and wild wasps that again, will keep pests and undesired insects under control. Maybe some butterwort will grow there as well at higher level, which are pretty rare plants. Most herbs also provide a rich nectar and pollen source for a lot of insects.
Sandy hill
A relatively tight clay/sand hill constitutes a perfect habitat for a lot of wild bees and wild wasps as well as beetles. Big enough and with some decorative rubblestones it may be a suitable habitat for some locusts that can have gorgeous colors as well. With some more structured stones and wholes, it may also attract lizards, that keep control on bigger insects, so they won't get too much. All of them help to keep your garden clean from pest and undesired guests. Just make sure, that it is not grown over by too many plants. However, a few small plants are not bad, as they structure the hill additionally with their roots.
Insect Hotel
If you don't have the space for a sandy hill or don't like it, you can also place an insect hotel, that is a suitable habitat for many wild insects as well. However, best would be both structures to maximize the biodiversity of insects in your garden. You can buy insect hotels, but it is very easy to build it yourself as well. Some of the material in those hotels should be renewed every year or every couple of years to prevent parasites from spreading, because they often stay in the dwelling of their hosts.
Rockwall / Stone Cairn
A nice habitat for lizards and snakes (with water nearby, maybe also for grass snake) would be a rockwall or stone cairn. Large enough and with bigger wholes and crevices, it may be also suitable for bumblebees, bees and wasps and their nests. Especially snakes will keep amphibians like toads and frogs under control. Usually, you must not fear any dangerous or poisonous snakes, as most are very shy and poisonous snakes usually, like living in or nearby forests and marshes. This habitat can be easily combined with the sandy hill or the herb mountain as well, providing space and habitat for many animals at the same time.
Bat boxes
Bats are capable to keep away annoying insects during evening and night. A bat box should be not directly beneath the house, as the animals may feel disturbed by human presence. Furthermore, they produce a bit dirt (faeces under their nests). But with faeces, they also gather nutrients under their nests, which may be beneficial for some plants like nettles (wash it extra well, if you like to eat it!!!). Bats theoretically can have rabies, but only very rare cases are known und usually they don't bite human. But in case you have been bitten, you should check this, just to be sure. There are different bat boxes for different bat species. I can recommend to use boxes for example for the noctule (Nyctalus noctula). It is the biggest bat in middle Europe (so you may can observe them better, if you like) and they already start hunting during sunset and until sunrise (with a pause during midnight and very early morning). Those bats are migrating, so they probably won't be around during summer, which is beneficial as potential germs and parasites in their boxes will die until they come back (you may also clean the box during this time). However, males don't migrate and the group will have several spots to sleep. So they may won't be around each night. Another nice bat may be the Natterer's bat (Myotis nattereri), which is smaller and hunts more during the night.
Bird boxes or nest structures
You can also provide boxes for birds. But usually they will find places and build nests in suitable habitats on their own. To support the birds it is beneficial to have some trees (the older, the better) and different shrubs (e.g. sloe or dogwood). Boxwood is not the best choice, as it often is too dense for birds. At least it should not be the only shrub species.
Pond & stream
If you have or want to establish a pond and/or a small stream make sure you have some areas with a stronger flow. You may can achieve this by placing some bigger stones or a couple of rubblestones here and there. This will raise the solved oxygen in the water. But keep also areas that are more calm. Both is important for caddis fly and dragonfly larvae that will prey upon other aquatic insects and insect larvae like mosquito larvae as well as on flying insects after maturity. But try to avoid very stale water areas as those are beneficial for pest like mosquitoes and leech and for undesired algae development. Of course you should still have some algae that would serve as food source for other invertebrate zooplankton. The best way to achieve all those mentioned habitat structures is to have a moderately deep to deep pond where a stream flows in and out on the other side (or a bit shifted to one side) at a pretty high level. On the edges of the pond you can grow diverse plants like loosestrife, lily and reed. The latter is especially useful as a natural sewage treatment plant and as habitat for water fowl and amphibians. But be careful: it spreads over and underground by rhizomes and may forms a very dense belt around your pond if you don't cut it. Make sure, that it only forms some dense spots at the edges. The ground of the pond should contain several structures, like areas with makrophytes (bigger water plants), stony ground with a heterogeneous structure (wholes, etc.) and maybe a broken branch of a tree. This will help different animals to establish a population and increase the biodiversity.
Additionally, depending on the size of your pond, you can try to introduce zooplankton like water fleas (i.e. Daphnia) and zoobenthos like freshwater shrimp (i.e. Gammarus pulex), but they may spread there from surrounding water bodies anyway if the habitat is suitable and they find a dispersal vector (some can spread by attaching eggs on ducks, for example). Invertebrates are very important as they constitute the basis of the food web surrounding the pond from other insects over amphibians to birds. Furthermore, they feed on leaves and other dead matter that falls into the water and help keeping a good water quality. If you are able to observe salamanders or newts you can be sure, that the water quality and habitat structure is very good! Makrophytes like water lily and stoneworts help to keep algae within a limit by gathering nutrients that are then not available for algae any more. At slower water flow, algal blooms can be prevented by water fleas as well. In further articles, I will also present some plants, that should be avoided in a pond as they are invasive.
Keep your garden a bit messy
Yes, this may help you not only as an excuse to leave things as they are, but also to turn your garden in a proper home for helpful animals. To mention one of the most important and also endangered animal, you will provide a home for the hedgehog. Leave some dead wood at the edges of your garden, and don't remove all foliage that has fallen down in autumn. They are very nice shelters for hedgehogs, frogs, toads and beetles that in turn will prey upon slugs or their eggs and other annoying animals. You can also gather some of the wood and foliage at a few spots to create woody piles. If you are lucky, they will be occupied by different animals. Once established, you should leave those piles alone, to prevent disturbance of the animals. During summer and in autumn, you may clean and renew some parts of the piles, to prevent parasites to grow and spread.
Even though this article became pretty long, I hope those ideas inspired you to create an ecologically valuable and functional garden. Furthermore, I would love to get further ideas of habitat structures and tips from you. Just add comments below and we can discuss them. I may add them to this article as well.
Small Disclaimer: I do or did not receive any money or other benefits by posting the links above. It is not meant as advertisement. I just like the pages linked.