Which to plant? Deciduous or coniferous?

Trees are important. This is a phrase you hear a lot and every one of you reading this is likely to agree. However, are some trees more important than others? To answer this, we must look at the different types of trees, or more specifically, two types of tree. These are known as deciduous and coniferous trees. Many people have heard these terms; however, they are often overlooked when discussing the environmental importance of trees and so here is a brief distinction between them. The term deciduous literally means “falling off at maturity” and refers to the shedding of leaves during the winter months which then regrow later in the year, as well as the growth and loss of flowers and fruits which also occurs during this time. There are many examples of deciduous trees with some notable UK examples including Oak, Birch and Ash. Coniferous trees on the other hand, are recognised by their needle-like leaves that remain connected year-round and their use of cones as seeds instead of fruits or flowers. The most well-known example of a UK conifer is the Scots pine, and most species have some resemblance to the traditional Christmas tree image. These two types of trees function very differently and so have a widely differing impacts on their environment. To truly understand this difference, we must first look at the many wonderous species that call these trees home…

Yew Tree

Apple tree

(Pinecone vs fruit comparison picture or a Needle vs leaf comparison picture)

 Trees are crucial to a healthy UK ecosystem as they provide food, shelter and protection from predators. Almost every UK species will utilise trees in its survival to some degree. This could be anything from a sparrow hawk raising its young in a treetop nest to a roe deer sitting in shade during a hot day. From a bustling ant colony to the green woodpecker trying to catch them. A single Oak tree can support many hundreds of species from insects to mammals and each of these animals has co-evolved with these trees over millions of years to perfectly make use of its different components. This occurs throughout its lifetime and continues past its death where detritivores such as millipedes begin to break down the dead wood into nutrients. A single oak tree can support over 284 different insect species! These species dependencies occur for both deciduous and coniferous trees, however it has been commonly reported that the many coniferous plantations we have in the UK have poor species diversity. How could this be, especially as these plantations often make up larger forests than their deciduous counterparts? The answer is ominous; a large proportion of the British public may not be aware that many of the forests they enjoy are actually filled with invaders…

Woodland represents 13% of the UK’s total land area and 36% of this is non-native. Non-native species are tree species that have not co-evolved with the surrounding environment and have instead been introduced by people. They therefore provide far fewer benefits to British wildlife as these animals have not adapted to utilise these specific trees for their survival. Compare the native oak tree with its 284 supported insects to the non-native horse-chestnut which supports around 4. They can also have negative effects on the surrounding environmental conditions such as soil and water quality. These non-native trees are often deliberately introduced into large-scale plantations to be used for timber or other materials due to their quick growth rates.

So where does this link in with the coniferous versus deciduous investigation? Well, virtually all these plantations are made up of conifer trees with a small proportion being native. 51% of the UK’S entire coniferous woodland area is from one single species, the Sitka spruce. This non-native species was brought to the UK from the US in 1831 for its fast-growing properties and is planted in large quantities without mixing with other tree species, this is known as a monoculture. These spruce monocultures provide very little benefit as a food or habitat source for animals as they are non-native and their dense growth patterns prevents other plants occupying this area that could provide these resources. Overall, this is a less than favourable situation for our woodland and by looking at the percentages it may seem that all is lost. However, gradual changes can be made to improve our woodland and in time, the wildlife can return.  

The main focus with UK woodland is finding a suitable balance. It is easy to say that the Sitka spruce is less beneficial to animals and therefore should be replaced, however it is also incredibly useful and cost effective to produce. Replacing it with native conifers is not very feasible as they are not as cost effective and as we only have three native species we are not exactly spoiled for choice. Losing these non-native plantations would also impact our economy and thereby could reduce the funding going into protecting our wildlife. The solution must provide benefits to wildlife without infringing on the UK’s economic development, and this is quite the tightrope to walk. However, throughout the UK, many projects are aiming to do just that. The Scottish Wildlife trust has stated its aim to have all its large conifer plantations comprised of 25% native trees. This could be considered a broad unspecified statement but is an encouraging message from a large organisation which would significantly improve the state of British woodland and its species. Other organisations such as the Woodland Trust are dedicated solely to the protection and enhancement of UK woodland with regard to government legislation and economic benefits, originating from the need to prevent the further spread of conifer plantations in 1972. More recent projects like ours are determined to grow and fight for a healthy UK woodland the same way as these organisations before (learn more about us here). 

So, are conifer or deciduous trees more beneficial? Well as you might have guessed, that’s not an easy question to answer. Coniferous and deciduous trees both have very different roles in the UK environment due to the abundance of non-native conifer plantations. When evaluating the number of supported species in these woodlands, we must look deeper than just these two options. We must consider the native verses non-native tree types, the monocultures and the variety of surrounding economic and environmental factors. The UK’s reliance on non-native species complicates the protection of the our wildlife, however ongoing projects such as ours are working towards a goal where the natural environment can thrive without the need to impact the economy that helps fund it.

 By George Havill - Conservationist