Trees offer several benefits ranging from boosting the value of a property and maintaining a balanced ecosystem to helping the environment. Trees are undoubtedly aesthetically pleasing, and many hold historical significance, especially those that have been around for decades.

Removing a tree can negatively affect the ecosystem. For example, some trees serve as homes for animal species. If you cut them down, then they will lose their habitat. Not only that, trees help prevent flooding. Cutting them down means the area will be more prone to it.

Trees also help improve the quality of the air through the production of oxygen and the absorption of carbon dioxide. If you remove a tree, it’ll also affect the process of photosynthesis that plants go through in your area.

Now, if you’re planning to develop a certain property, the trees within the area may be affected. You need to have a tree survey to help you decide how to proceed.

Understanding the process involved in a tree survey

A qualified and experienced arboriculturist should perform the tree survey. The first step is what is referred to as the stage one survey or the BS5837 tree survey. The potential effect of new construction on trees and the environment needs to be assessed.

A BS5837 tree survey is a British Standard survey involving performing the relevant checks. It is a must for any design work, demolition, or construction job that could potentially put trees at risk.

The arboriculturist will ask you some questions before the tree survey begins. The said inquiries will be about the development, such as your plans with the area and the other details on how you plan to proceed with the site development.

You also need to provide a site plan. Once all details have been provided, the arboriculturist will perform the tree survey.

What is the purpose of a tree survey?

Through the BS5837 survey, you and the local planning authority would learn the practical constraints to the land and the development. The survey is performed using professional equipment that allows the experts to gather specific data, such as the condition of the trees and what species they belong to.

What is a BS5837 retention category?

All trees within and near your site will fall under the retention category. Under this category, you’ll receive crucial information from the tree survey. There are four categories, A, B, C, and U.

Category A is where the ones with the highest classification fall. The trees that are added to this category are in good health. They are also prominent and possess essential qualities like adding cultural values to the site. Trees under category A are expected to offer up contributions for more than forty years. You will be allowed to do any work below or above ground within a certain distance of these trees unless necessary.

Category B is similar to Category A but only has an expected contribution of about 20 years. The local authorities would like the trees under this category to be preserved. But if they need to be removed, you have to plant another one to replace them.

Category C is where trees that are in poor condition fall under. They’re not a risk for planning and only have about ten years of contribution. Despite their condition, the local authorities may still require you to plant a new one to replace the tree you wish to remove.

Category U, the final category, is where dying or dead trees fall under. They pose a safety risk and have less than ten years of contribution. They have to be removed regardless of whether they interfere or not with your development or the site in question.

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Concerning tree law in the UK, several critical factors exist to consider. The following guide provides more information on some of these essential factors.

Dangerous trees
In almost all cases, the one responsible for trees' safety is the landowner where the trees in question grow. There are some exceptions, such as when a rental agreement puts the tenant in charge of tree management. In all other cases, the tree manager has a duty of care to provide care such that their neighbours don't experience any problems. A tree owner also has the duty under the Occupiers Liability Acts to take proactive steps in ensuring visitors on the land are safe. This means that if a tree falls, the owner is liable. If it is proven that the owner has been negligent, such as allowing tree damage to corrupt the tree, then they can face the law. To avoid this, tree owners should always look to inspect their trees with the aid of arboriculturists.

Encroaching roots and overhanging trees
In general, the 'common law' makes provisions for pruning branches and roots that go over the boundary between properties even without consent from the owner. However, any works undertaken should be meticulous not to damage the tree because such acts are liable. It is always best to discuss matters with the tree owner before taking action. Consulting an arboriculturist, in this case, is always a good idea. If overhanging branches or encroaching roots have caused damage to a property, the insurer will approach the owner to decrease the issue and arrange repairs.

Tree protection
There are a few ways for trees to be protected in the UK.
Tree Preservation Orders (TPOs) – Local Councils, within their role as Local Planning Authority, administer TPOs. Their goal is to protect trees that add amenity value to the area. A TPO means it is an offence to top, lop, uproot or cut down a tree under protection without the local planning authority's consent. Hedges, bushes and shrubs cannot fall under a TPO, but it can be made for anything from a specific tree to an entire woodland. Anyone wishing to work on trees under a TPO should fill out an application form and send it to their local planning authority.

Conservation areas

parties that wish to do any work on conservation areas, need to send out six weeks prior notice via email, letter or the official form with a detailed explanation of the proposed results. The local planning authority can issue a Tree Preservation Order during that time.

Restrictive covenants

Essentially a promise between two parties, such as the buyer and seller of a property/land, to not do certain things to the area. It is binding to the land and not an individual owner, meaning it is a place even if the current owner sells the property to another owner.

Felling licenses
Felling a tree in a garden is possible, even without a felling license. However, for a tree outside a garden, applying to the Forestry Commission for a felling license is always recommended. This is regardless of whether a TPO covers the tree in question.

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Tree Preservation Orders (TPOs) are issued by local authorities to protect the countryside. They extend over individual trees of high amenity value or entire woodlands. 

Under the Countryside and Rights of Way Act, local planning authorities create Tree Preservation Orders. Whether they cover individual trees, groups of trees or woodlands, TPOs protect the trees that they cover from removal, improper pruning or any sort of action against them. Any action that would result in significant loss of amenity provided by the trees is considered to be against the law. Authorities usually exercise their judgement when they make TPO because ‘amenity’ is not defined in the law. The general purpose of a TPO is to protect woodlands and specific trees the removal of which will impact the community and the environment in a notable negative way. Before the local authority comes up with a TPO, they first ensure the public will benefit from the presence of trees/woodlands in question. 

Once a TPO is out, there it is possible to apply for the removal/pruning of protected trees. 

Applying for doing physical work on a protected tree 

Before you do any sort of work on protected trees, you must obtain permission from the local authority. It takes about 8 weeks from the date you submit the form called ‘Formal application to carry out works to protect trees. You will have to include a detailed description of the proposed work, in addition to a map of the trees. It is important to mention that arboricultural consultants can act as agents in applying to performing a tree survey. They can also advise you on the likely works that will be allowed. 

If the local authority decides not to grant permission for works, then you can take your appeal to the Secretary of state. It is important to understand that you need to have very reasonable grounds for appeal and you will most likely require agents to act on your behalf. Typically, arboricultural consultants will be of great help in the matter. They can launch a formal appeal, to give you the best chances of success. The allowed period for appeal is 28 days. 

TPO objection 

In regards to the provisional TPO, local authorities need to consider all representations made about it. What this means is that you will have some time to place some arguments against the TPO, before it comes to pass. Once again, you can work with arboricultural consultants to advise you. They know just what procedures the local authority needs to follow and the guidelines laid down by the higher authorities for confirming and revoking a TPO. In other words, the consultancy will know whether the local planning authority has not followed the exact procedures and guidelines, and they will then represent you with the objection. 

Challenging a TPO at the high court 

When a TPO is confirmed, there is no longer the option to appeal to the Secretary of State. Yet, there is a chance to apply to the High Court to quash the order. Such actions typically call the legality of the order into question. 

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In the past, people used a combination of pulling and winching tests to research various tree biomechanics. The goal of those was to determine their resistance and how durable against rupture and uprooting they were. As a result of such tests, the tree was usually brought to ultimate failure and destruction. 

Nowadays arborists and arboricultural consultants employ a set of non-invasive tree risks assessment techniques, which preserve the trees they are conducted on. Static load tests are now the common method that experts utilise after it was developed at the University of Stuttgart in Germany. 

A static load test consists of three steps: 

• Pulling test – this methodology aims to assess the risk of failure (usually related to uprooting or stem breakage). It is achieved by pulling the tree to simulate wind loading in moderate power. Things like root plate inclination and changes in the length of fibres are then measured to determine the results. As for the tools used for the job, it is usually a rope winch or a grip hoist that apply quasi-static forces then measured by an in-line dynamometer. The idea behind the test is simple – as the tree experiences increased load, its stem will bend and the root plate will tilt. Arborists can detect these changes with very sensitive instruments. By then looking at the degree of compression and exerted extension within marginal fibres, the experts can better determine fracture resistance. 
  
  
• Wind load analysis – the goal of this test is to produce an estimate of the expected wind load of the given location. Any safe tree needs to be able to withstand the wind effects, as well as snow and ice. Wind loads depend on a few factors, such as expected wind speed and resistance of the tree to streaming air. The way to perform such analysis is to extract the crown in a digital picture and then the different levels are correlated with the wind speed. Experts are always mindful of the fact that wind speed increases with height above ground. There are national wind zone maps, which determine reference wind speeds and wind events. By using species-dependent parameters, experts are then able to assess the reaction of the tree to the wind. That is how they can streamline the crown or recommend a reduction in tree height. 
  
  
• Evaluation – once the required tests have been performed, arborists can begin the assessment and evaluation process by using the acquired data. The goal is to get enough information on the critical load of the tree and whether the conditions and environment it is in are potentially dangerous to it. The analysis results in factors of safety, with a value of 1 when the resistance against failure matches the expected wind load. However, according to most engineering standards, structures should have a factor of safety equal to 1.5, which is the aim of any static load test. 
  
  

It should be pointed out that trees often compensate for insufficient strength by utilising adaptive growth. Arborists will always take into consideration a tree’s ability to produce additional wood fibres in the areas of excess strain, often just by visually inspecting the tree. This aspect of the job is essential to deducing meaningful recommendations by arborists, who correlate results of technical inspections with their visual assessments. 

There are still certain limitations that any such project presents, namely the majority of factors at play. In the future, these tests will be better able to produce meaningful information. 

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Many people consider deadwood as a long-gone part of the tree, as it is not even a living part attached to the tree anymore. However, the more correct way of referring to it is as ‘decaying’, instead of dead. It contributes to the diverse ecosystems that trees are part of and is not just a static limb. 

Decay essentially means a progression of use by a number of different organisms. Some organisms thrive in fresh wood, while others are involved in the breakdown of woody tissues. In some sense, decaying wood can be considered a habitat in its own right. Woodland managers and arborists often remove deadwood on the principle of hygiene. Doing so protects the remaining timber resources from various pests, like fungi and insects. This is especially the case in public parks and gardens, where dead wood is in fact a serious risk for people and property. But there is a problem with this, and it lies in the fact that many important species don’t find the necessary habitat to live and thrive. As a result, the arboreal system experiences a serious downside due to the lack of deadwood. 

The way that deadwood positively impacts arboreal ecosystems lies with factors like carbon storage, biodiversity, soil nutrients cycling, energy flows and hydrological processes. And while all of that is now largely understood by arborists, many of the previous generations of them have been focused on clearing deadwood. 

One example of the issue of clearing deadwood completely lies with some of the rare species, associated with veteran and ancient trees. A lot of them can only be found on sites with a higher amount of decaying wood. With organisms that rely on decaying wood becoming more isolated, trees are more vulnerable than ever. 

The signs of decaying wood habitats 

There are 2 recognised signs of decaying wood habitats. One has to do with standing trunks, branches and limbs around the tree. The second is cavities within the trunk and branches, where decay is taking effect. The habitats created because of these processes are different and recreating them takes different techniques. 

• Standing deadwood – regardless if it is about branches or whole trunks, standing deadwood is easier to recreate. There are a few techniques that arborists utilise, such as destructive pruning and ring barking trunks and branches. This type of decay takes place from the outside in, creating the ideal habitat for invertebrates, lichens and fungi. 
  
  
• Decay within the trunks/branches – the techniques involved in recreating this sort of decay are much more complex. Since the decay decomposes from the inside out. It creates cavities within seemingly healthy trunks, which are then populated by fungi and invertebrates. 
  
  

The methods utilised in creating a habitat

• Destructive pruning – often used to create a habitat in trees. It involves techniques like decay creation within the trunk and the main branch structure of the trees. 
  
  
• Veteranisation – this is a pruning technique, which aims to ‘age’ a tree prematurely in a more controlled manner. The goal is to create a habitat and stimulate the formation of another secondary crown. 
  
  
• Natural fracture pruning – these are pruning techniques that mimic the natural process of branch loss, such as after severe storms. Small branches can be cut from the above side and removed from the crown. By leaving a fractured or split branch at the end, they remain unassociated with existing growing points. 
  
  

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