Encourage biodiversity

You should also consider the variety and spatial distribution of tree and shrub species in the canopy and understory. 

The traits of each tree and shrub species affect the community of associated species and the delivery of ecosystem services. For example, the: 

• level of shade cast 
• water-holding capacity of its bark 
• nutritional value of its leaf litter 

Native tree species are particularly valuable for biodiversity. So, increasing the proportion of native trees is a simple way to increase species diversity in your woodland.

Several major factors can contribute to unfavourable ecological condition of woodlands in Scotland. Including pressures due to:

• pests and diseases 
• invasive non-native plants 
• damage by wild and domestic animals 

Therefore, managers should prioritise the following actions, as necessary for their circumstances:

Manage populations of mammalian herbivores that are damaging their woodlands 

Typically, deer are the main problem, but brown hares and sheep can also over-browse trees and understorey vegetation.

Reduce or, ideally, remove non-native plants that can out-compete and replace native plant species 

For example, species such as rhododendron are not used by many native species of animal. If rhododendron proliferates, it will much reduce biodiversity in a woodland. Other non-native plants present similar problems for woodland managers, such as

• Himalayan balsam
• Japanese knotweed
• giant hogweed

Take action to minimise the impact of pest and diseases 

This is a growing issue and managing tree diseases involves a combination of proactive and reactive measures, focusing on: 

• prevention
• early detection
• effective intervention 

You should: 

• implement biosecurity protocols
• monitor for disease symptoms
• employ management techniques such as thinning of stands of trees to improve airflow and reduce humidity, which can reduce the suitability for fungal diseases

One particularly effective way to improve biodiversity in your woodland is to increase the amount and diversity of deadwood.

Deadwood provides a habitat and food resources for thousands of species of: 

• animals
• plants
• bryophytes
• lichen
• fungi
• unknown but enormous numbers of microbes 

This habitat is ‘partitioned’ into innumerable ecological niches, with each species occupying a different niche according to parameters such as tree:

• species
• diameter
• age
• exposure (the drying effects of sun and wind)

Different groups of organisms use deadwood at different stages of decay. 

This is because the physical nature of deadwood changes through time due to processes of decay. 

Deadwood is therefore a diverse and dynamic habitat, and different organisms require different kinds of deadwood spread differently through space and time. 

This is problematic for woodland managers trying to create the ‘best’ deadwood resource to enhance biodiversity on their land.

Simply put, it is impossible for managers to provide habitat for all saproxylic (deadwood dependent) species all the time. 

Given there is no single ‘solution’ to providing deadwood habitat, it is best to adopt a set of management principles when planning and delivering deadwood. 

The following set of principles reflects the consistent findings of research across various deadwood taxa. This will maximise the overall biodiversity benefits that can be accrued from deadwood. 

The principles are underpinned by research and management experience: 

1. retain and create as much deadwood as possible and create new deadwood on a continuing basis 
2. retain and create as many kinds of deadwood as possible 
3. favour native tree species when creating and retaining deadwood 
4. favour the retention and creation of large-diameter deadwood 
5. retain and create high stumps and snags (standing deadwood) within woodland and permanent open areas (but not on clear fells that will be restocked) 
6. design the distribution of deadwood to maximise connectivity at the stand scale and at the woodland scale