Management for biodiversity

Biodiversity is a term which simply means 'the variety of life'. In order to ensure high biodiversity within a woodland, the woodland manager aims to provide a whole range of habitats and microhabitats. This is done by encouraging high plant diversity, managing the structure of the wood to provide a variety of microhabitats and retaining 'waste' products such as rotting wood. Management will need to take into account physical characteristics of individual woods such as topography, soil type, rainfall and aspect.

A reasonable diversity of native plants (examples) can be planted or encouraged by management. Plant species vary in the number of invertebrate species which they will support. Native species will support more invertebrate species than introduced ones. More here. Willow (left) plays host to a staggering 450 different invertebrate species, including the aphids which these ants protect in return for honeydew. Different types of tree also differ in their value as habitats for a variety of lichens.

Biodiversity may be enhanced by planting trees which will support large numbers of invertebrate species. However, there is a caveat here. Some tree species, although poor in the number of invertebrates which they support, may be the sole food plant for some of those species. They are therefore vital for the species dependent on them.

Tree value for invertebrates and lichens

Increasing the light levels under the main tree canopy will greatly benefit plant diversity within a woodland. To achieve this, the canopy should be opened up by thinning out poorer specimens of trees to create glades, or by planting young trees a greater distance apart. This will allow more light to reach the woodland floor. This in turn encourages the development of field and ground layers within the wood. (More on biodiversity and light here.)

The more different types of plants there are within a wood, the greater the variety of food sources available for invertebrates, birds and mammals. This will include the leaves, flowers (of insect-pollinated plants), fruits, nuts and seeds of the plants. The presence of a variety of plants with different flowering and fruiting periods will also ensure that food of one kind or another is available most times of the year. In addition, if one particular plant species has a bad year, it will be less likely to have devastating effects on the animal population because there will be other alternative food sources.