Trees for bees: the right species

Bees play a very important role in our food chain so these days a lot of attention is being paid to these diligent creatures. The planting of trees that supply bees with their food, known as honey plants, is therefore popular and has, in fact, become necessary. In order of flowering time, a few excellent species are willow, maple, horse-chestnut, acacia and linden. These trees provide high levels of pollen and nectar that bees need for their existence. There are also countless other species and, of course, we must not forget fruit trees either. In gardens, ornamental fruit trees may be an interesting choice, although it is important to realise that species that have double or filled flowers, such as many decorative Japanese cherry trees, do not produce nectar or pollen, whereas the species and varieties with single flowers do.

Large trees give more to bees

If a honey plant is to produce good nectar and pollen, it is important that the growing circumstances are right and that there is sufficient water in the weeks before and during flowering. This keeps the nectar flowing freely. Trees that have reached a certain stage of maturity and have a substantial crown flower the most and are therefore the richest source of nectar and pollen. It is also important that there are enough honey plants available during the flying season, which lasts from March to October. Many honey plants flower in spring or summer, but as the year progresses, the flowering varieties become more and more limited. There are a few species which still bear the occasional flower until into September and these are visited by huge numbers of bees. The best known, and appropriately named ones, are the honey tree (Styphnolobium/Sophora) and the bee-bee tree (Tetradium). Click here download the "Trees for bees calendar"

Honey plants are vital

Mankind likes making use of bees. We do not always realise it but it is thanks to their efforts that we are able to enjoy such a wide range of food products. Around 30% of our daily food requirements depends on bees. Without bees there would be no apples, pears, walnuts, almonds, courgettes or capsicums and we could forget our daily cup of coffee too.

However, honey bees are going through very difficult times due to the Varroa destructor, a millimetre long parasite, large numbers of which have been weakening the colonies since the early eighties. In addition, bees have faced a reduction in food as a result of urbanisation and a huge decline of available countryside. The use of insecticides and fungicides has also caused a reduction in the bee population. Fields and meadows offer little in the way of food as herbicides have destroyed many useful plants, leaving behind fields of grass and flowerless corn and grain

Large trees make all the difference

In towns and villages there is often little room for decent-sized green areas. Nevertheless, trees enable the creation of areas high above street level. Moreover, the blossoming area of a tree is many times greater than its crown projection which means it produces more flowers compared to a plant at street level. The older the tree and the larger the crown, the better. The same applies to trees growing in parks and along country lanes.

Obviously, only species of trees that produce nectar and pollen are of any interest to bees. These trees are called honey plants and a few very good examples, in order of flowering, are willow, maple, horse chestnut, acacia and linden. There are also countless other significant species and, of course, we must not forget fruit trees.

If a honey plant is to produce good nectar and pollen, it is important that the growing circumstances are right and that there is sufficient water in the weeks before and during flowering. This is particularly important for the flow of nectar, which will stagnate if there is a limited amount of moisture. We should not expect too much from young, newly planted trees either. Fortunately we do not usually plant trees for a short period as it sometimes takes years for them to flower. Trees can only make a difference if they are able to grow to maturity and develop a robust crown. When the nectar and pollen production is good, for instance on a linden, a colony of bees can easily collect 20-30 kg of honey in two weeks, although this is also possible, to a lesser extent, with a mix of species that flower slightly earlier on the season. An important difference is that the bee colonies are smaller in spring than they are in summer, so they have fewer ‘staff’ available for gathering the nectar and pollen.

The pollination of flowers is an incidental result of collecting nectar and pollen. Bees are only concerned about getting food, but for trees, whose existence is dependent on insects, a visit from a bee or bumblebee is of vital importance. The tree attracts them with nectar deep in the flowers. The bees and bumblebees come long for this and sweep their bodies against the pollen-bearing anthers. The pollen gets into the hairs and is transported to the next flower, completing he pollination process. The nectar provides the bees with fuel during their flight and the little extra that is collected gets delivered to the colony where it is turned into honey and stored for winter.

During its flight, the bee wipes its body clean of pollen which it transfers to special pollen baskets on its hind legs. This protein-rich pollen is used as food for its larvae.

Bees are interested in large amounts of nectar and pollen and they stick to one type of flower. Once they have found a crop that provides them with tasty food, they announce this to the colony with the bee dance, after which they keep on coming back until the nectar is all gone. Under the right circumstances, an excess of the same kind of nectar is collected and a certain type of honey is produced, depending on the species of tree for example, willow or linden.

A contribution of Frank Moens van de Nederlandse Bijenhouders Vereniging (NBV)

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