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Life cycle of a tree: from seed to snag

Have you ever wondered what a tiny seed has to do to become a tree? If so, then this blog is for you, as we go on a journey to look at all the different stages in the life of a tree from seed to snag.

The seed is a design used by trees for millennia to ensure the next generation of trees exist. It has evolved into many sizes and shapes to exploit a whole range of dispersal techniques, including wind, water and animals. Inside a seed are all the resources needed to allow it to survive independently for a period of time, in order to reach a safe place to germinate.

Seeds are adapted to use different methods of dispersal (Photo: WTML/B Lee)

Sprout (Germination)

Once the seed has arrived at its destination it needs to secure itself. This is done in the first stages of establishment. The primary (radical) root breaks through the seed, anchoring the seed and providing water to the developing plant. The next stage in germination is the emergence of the embryotic shoot.

The shoot consists of three parts: the shoot leaf (cotyledons) and the two sections of the shoot located above and below the cotyledons. The shoot at this stage has two different options available for development. It can grow from below the shoot leaf, pushing the whole shoot up through the soil, or from above the shoot leaf, pulling only the tip of the shoot up through the soil and leaving the primary leaf underground to rot.

Seedlings

Once above ground the shoot becomes a seedling. This is the stage in the tree’s life cycle when it is most at risk from diseases and damage, and considered to last until the tree is three feet tall. If the seedling remains unbranched in this stage it is referred to as a whip.

Sapling

A tree over 3ft tall is often considered a sapling. The duration for which a tree will remain a sapling depends on the species. Typically saplings have defining characteristics which are distinct from a mature tree. The trunk is normally more flexible and the bark is often smoother and thinner than in later life. Saplings are also unable to produce flowers or fruit.

Trees with really long life spans like yews and oaks will remain a sapling for far longer than shorter-lived species like silver birch or wild cherry.

Mature tree

Once a tree is producing flowers or fruits it stops being classed as a sapling and enters the next stage of its life. In this stage the tree will be at its most productive. The duration of this productivity depends on the species in question.

A typical English oak tree starts producing acorns at around 40 years old, peaking at around 80-120 years. Rowan starts producing berries at approximately 15 years, and by 120 years will be around the end of their life cycle. Oaks can be productive for 300 years and then rest for 300 years before entering the next stage in their life cycle.

A mature tree will start to develop seeds and fruit (Photo: WTML/B Lee)

Ancient trees

The next stage of a tree’s life comes when a tree passes beyond maturity and is old, when compared with other trees of the same species. This stage is when a tree is known as an ancient tree. Depending on the species a tree may be called ancient when it’s only in its early hundreds like rowan or when it is thousands of years old like yew. For this reason it is not possible to define ancient trees by their age. Typically ancient tree can be identified by characteristics, for example they may have a small canopy and a wide truck which is likely to be hollow.

The Woodland Trust is running The Ancient Tree Inventory, which aims to creating a map of all the UK’s ancient trees. This is a crucial tool used by planners, developers and ecologists to identify and protect the oldest and most important trees across the UK. It can also help you locate your nearest ancient trees and if you know about any ancient trees that are not on the map then you could always submit your records by our website.

Decaying tree (Snag)

A snag refers to a tree that is in the final stages of its life. This term incorporates dead standing trees and dying trees. The tree itself has reached the end of its life; however its usefulness to wildlife is about to peak. Dead wood provides homes to insects, which are a food source for birds, bats and other small mammals. These creatures also take advantage of hollows or holes in the tree for shelter. In turn these smaller residents are food for larger mammals and birds like owls. Removing dead wood from woodland removes an important part of its biodiversity.

Ensuring the future of native trees

Thanks to funding from the players of the People’s Postcode Lottery the UKNTSP is collecting tree seeds and storing them to safeguard the future of our native trees. The project is also working on increasing our understanding of seed germination and dormancy processes. Find out more about the research going on with UK native seeds.