Biodiversity in the back garden
A possible definition of Biodiversity could be: the variability among living organisms from all sources, including, inter alia, terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems”
“Bio” means life and “diversity” means variety within the living world. Everything is interconnected: A pair of Great tits feeding their young need caterpillars during the breeding season. Those caterpillars can only live if certain food plants are available and in order to have enough caterpillars, we must have enough moths or butterflies that are able to produce caterpillars. These butterflies and moths in their turn need flowers, which in their turn need pollinators to survive and to reproduce.
Far too often people think of what they cannot do: that very rare butterfly that can only survive because of a Gentian will probably not come into your garden but there is so much you can do to improve the conditions for wildlife, plants, and the living world. With this blog, I show you my modest approach to increasing the biodiversity in my own back garden.
Even the smallest garden can have a mini pond. My pond does not contain any fish: fish and amphibians do not go well together as most fish prey on young amphibians. I gave the fish to a friend of mine who has a pond with fish and she was delighted. Everybody happy! After the long and cold winter it is so exciting to see the first newts in the pond, sometimes even as early as February. Frog spawn is usually around March/ April in huge numbers and some people were worried that I would end up with thousands of little frogs but rest assured: tadpoles and frog spawn is on the menu of many predators: newts love frog spawn and tadpoles and dragon fly larvae are also ferocious predators of tadpoles. Below is a picture of a very young smooth newt that left the pond seeking a place to hide on land.
Frogs, toads and newts spend a short period of their lives in the water so if you have these beautiful and fascinating animals in your garden, please make sure you provide a habitat for them during the time they are out of the water so that they can have enough to eat and find a place to hide. In my garden, there is enough vegetation, a compost heap and lots of dead wood.
Dead wood in the garden
Dead wood is very important for biodiversity. It is estimated that a third of forest-dwelling species rely on dead or dying trees, logs, and branches for their survival. Many fungi can only thrive on dead wood. Underneath the wood, it is teeming with life: centipedes, millipedes, woodlice, mites, all of which play a role in the ecosystem and they are a possible food source for wildlife.
Litter fall is often being cleaned up after winter and in spring we all rush to the garden centre to buy products to improve our garden soil. There is no need to do that as we can leave dead leaves in a sheltered area of the area and in two years we have leaf mould which improves the structure of the soil. The plant debris is composed of fallen leaves, twigs, pieces of bark, old fruits, etc. Bacteria, fungi and all sorts of insects convert the leaf litter into humus and nutrients are being recycled. Humus is valuable for our soil for it enable plants to absorb minerals and water better. Some leaves take a long time to decompose: needles of pine trees, beech and oak leaves take longer to compose compared to hazel, lime, Ash, Elm.
Flowers and plants
Flowers use colours, shapes, scent to advertise themselves. Flowers take on the crucial role of reproduction and they do this by making sure pollen is tranferred from one plant to another plant. Fact is that the plant is immobile so it needs a carrier to do this work. In our part of the world they use insects. Nectar and sometimes pollen is the reward that plants pay to insects for carrying pollen to another flower. It is a mutualism between two kingdoms of organisms: the plant gains reproductive success and the animal a food reward as it visits the plant.
There are numerous flowers and not all of them are equally valuable for wildlife. Bedding plants we often see in garden centres have often no value for pollinating insects: the flowers are often sterile, producing no pollen and nor do they produce nectar and in the rare occurence that they do produce small amounts of nectar, the insects cannot reach it. There are better options available.
In my garden, I have several plant families. The Labiates such as Lavender, Thyme, Marjoram, Dead Nettles are valuable for many bees: honeybees, solitary bees and bumblebees love these plants. Below the Spotted dead nettle. Labiates are an important food source for solitary bees that belong to the bee genus Anthophora.
Plants that belong to the Pea family or Fabaceae or Leguminosae, such as Vetches, Vetchlings (Lathyrus), Clovers are quite important as providers of pollen for bumblebees. They are of great importance as a source of nectar and extremely important and favoured as a source of pollen: A study into the main plant families visited by bumblebees showed that 61.6% of the visits done by bumblebees for pollen were on plants that belong to the Fabaceae family; in only 2.5% Lamiaceae were used as a pollen source. Below a picture of Bird’s-foot trefoil. They are also favoured as a nectar source so members of the plant family are great additions to the wildlife garden.
However, Red clover has flowers where nectar is hidden so deep that honeybees cannot reach it; this plant is mainly pollinated by bumblebees with long tongues.
Below a photograph of a solitary bee called Anthophora furcata, a bee with a very long tongue which enables the bee to drink nectar from flowers that have long flower tubes such as Wood sage as in the picture. Here she is collecting pollen for her young.
Plants that belong to the Daisy family or Asteraceae or Compositae offer nectar to bees with a relatively short tongue: Often you will see smaller solitary bees on these flowers. Plants that belong to this family are Common knapweed, Cornflower, Dandelion, Chicory and of course Asters. They are important as a pollen source for many solitary bees, beetles, etc.
Some plants like Verbascum do not produce nectar; the reward pollinating insects receive is pollen of excellent quality. Dark mullein is a beautiful plant and combines well with plants that provide mostly nectar such as Geranium species.
Pollen contains up to 40% protein and protein is needed to bring up young bees in the case of solitary bees, honeybees and bumblebees. Pollen contains amino acids (protein) but there is no single plant that produces pollen which contains all amino acids. The greater the variety, the better it is for the bee. Some plants lack a certain amino acid that is available in other plants. In this way, bees do receive all amino acids. Again, the plant family that produce pollen with a high protein percentage and of good quality, at least for bumblebees, are the Fabaceae.
Trees and shrubs
If you have the space you should consider planting an Oak. The Quercus robur or English oak supports more insects than any other tree except for the Willow. It is estimated that more than 400 species of insects and mites use the English oak as a food source whereas the American oak no more than 12. Now you know why birds are often found in Oak trees: they are like a restaurant for birds and offer plenty of food. In my garden I have planted the following trees/shrubs:
Common hawthorn: supports many insects, provides both pollen and nectar, berries are a good food source for birds.
Alder buckthorns: despit its inconspicuous flowers, this is a very important nectar and pollen source for bees, beetles, flies. Together with its close relative the Purging buckthorn, the only food plant for the caterpillars of the Brimstone butterfly. Birds love the berries. Flowers from May until September!
Purging buckthorn: Produces flowers in abundance during May-June.
Spindle: Small flowers, nectar easily accessible, beautiful poisonous berries in autumn.
Holly: Food plant for the Holly blue, provides both nectar and pollen.
Hazel: Many moth caterpillars feed on its leaves, soil improver.
Fruit trees: Apples and Cherries provide both lots of pollen and nectar, leaves are eaten by several moth caterpillars and you can harvest your own fruit in autumn!
Goat willow: One of the first available sources of nectar or pollen for emerging queen bumblebees: its leaves are eaten by many moth caterpillars. Male plants provide pollen and secrete some nectar, female only nectar. Below a female tree in flower.
Barberry: This spiny shrub offers both pollen and nectar and is covered in berries in autumn.
Suggestion: Some species are either female or male such as Holly. Please make sure you have a male Holly tree nearby if you want to have berries in autumn on the female tree.
There is no doubt i forgot to mention something but that will be for next time. Hope you enjoyed this blog and learned something new. Nature is amazing!!.