There are many arguments about which type of tree is 'better' but both broadleaves and conifers fulfil different roles within forest ecosystems. In this blog post, PhD candidate Kathleen Conroy, Trinity College Dublin walks us through the general characteristics of conifers and broadleaves.
Broadleaf
A member of the angiosperm family, broadleaf trees originated in the Permian period over 275 million years ago. All flowering plants are classified as angiosperms, and broadleaf trees flower and produce fruit. A majority of broadleaf tree species are deciduous, meaning seasonally they will lose their leaves (usually in autumn). By losing their leaves before winter, deciduous plants are conserving water, retaining energy and reducing the risk of winter storm damage.
The exact number of broadleaf species is unknown, but there are estimates of 50,000 species, with about 80% of these trees in tropical zones. This comes with the production of more dense wood which is the result of xylem vessels and growth processes. Broadleaf trees transport water and nutrients using these vessels. Because of the presence of xylem, broadleaves are classified as hardwoods, in terms of timber.
Broadleaf species often grow much more slowly when compared to conifers. This slow seasonal growth causes the density of the timber produced to increase. There are exceptions, but in general, timber produced from broadleaf species will have higher density than conifer timber. For example, hardwood is often used in flooring and boat construction, because of its maximum durability and strength. Ireland has many native broadleaf tree species including oak, ash and hazel. Beech, sycamore and horse chestnut are some of the non-native broadleaf tree species planted in Ireland.
Conifers
A member of the gymnosperms family, conifers originated in the Carboniferous period over 300 million years ago. Conifer is a Latin term meaning “cone-bearing”, a distinguishing feature as unlike other plants, conifers do not produce flowers and seeds, instead, reproduce via cones. Another noticeable feature of conifers is that a vast majority of them are evergreens. This means they will not lose their leaves in the autumn/winter. True conifer species will have needles as their leaves. The placement, shape, colour and size of needles can be used to identify species.
With over 600 species, conifers are divided into eight main families with the largest being Pinaceae (231 species), Podocarpaceae (174 species) and Cupressaceae (135 species). It is estimated that approximately 34% of conifer species are threatened with extinction and this number will continue to grow in coming years as the effects of climate change become more pronounced.
Conifer species are generally categorised as softwood species. The reason for this classification is due to the fact that conifers lack xylem vessels and instead use cells called tracheids for water and nutrient transport. This makes the timber they produce less dense and therefore “soft”. Another reason they are softwood is because they grow much faster than hardwood species. By growing more quickly, they are less dense. However, being soft gives it the ability to create versatile and valuable products. It can serve a number of purposes in the construction industry and other manufacturing purposes (e.g., furniture).
Ireland’s native conifers are yew, juniper and Scot’s pine. There are many examples of non native conifers in Ireland including Sitka spruce, lodgepole pine and Douglas fir. Most of the non-native trees have been introduced and planted into the Irish landscape to help meet the growing demand for timber.
Ecosystem Services
Broadleaves and conifers both provide a range of ecosystem services. They can provide some of the same ecosystem services, for example, both broadleaves and conifers sequester carbon. However, they can provide these ecosystem services to different extents. Fast growing conifers will sequester a lot of carbon when they are younger. Broadleaves, being slower growing, will continue to sequester carbon over a longer period of time (and often store carbon for a longer period of time as well).
Broadleaves and conifers also provide habitat for other species. Broadleaf forests are a well suited habitat for the protected red squirrel, while the protected hen harrier will nest in young conifer plantations.
Another important ecosystem service is the ability of forests to protect communities from flooding. Conifer forests can retain up to 10% more water than broadleaf forests (EEA 2020). These are just a few examples from the extensive list of ecosystem services that are provided by woodlands - and our sustainable forestry tool will help predict likely outcomes for ecosystem services using different forest management scenarios.
Broadleaves or conifers?
To date, Irish forests are approximately 61% coniferous and 27% broadleaf (DAFM 2022). Broadleaf afforestation is increasing but the majority of afforestation is of conifers. Broadleaves and conifers each hold essential roles in their ecosystems. It depends on the land manager and the ecosystem services that the land is required to produce. Both trees are needed to different extents to provide a suite of ecosystem services required by surrounding communities.
Sources:
DAFM, Johnstown Castle Estate, Co. Wexford. Department of Agriculture, Food and the Marine. 2022. Forest Statistics Ireland 2022.
Forests can help prevent floods and droughts (2020) European Environment Agency.
0from%20flooding. (Accessed: 21 March 2024).
