Trees are truly amazing and enrich our lives in many ways.
Trees, hedges, and woodlands have multiple benefits for people and nature; they are host to a range of wildlife species, provide us with clean air and offer protection against noise and pollution. Trees can reduce flooding as well as sequester and store carbon.
In a group, a line or standing tall on its own, a tree can be home to a wide variety of wildlife. It is estimated that an oak tree supports 2,300 species from birds and mammals to invertebrates, mosses and lichen.
From the top to the bottom, leaf to trunk, trees are a vital part of river and land ecosystems.
The tree canopy, leaves and branches intercept rain before it reaches the ground. Root systems help water penetrate into the soil reducing run-off and sedimentation, keeping nutrients in the soil. Riparian tree and hedge planting improves biodiversity along our rivers and connects vital habitats and species, filters water and slows run-off.
Roots help to stabilise riverbanks and when exposed in the water provide refuge for invertebrates and small fish. Leaf litter and woody materials provide food for many freshwater invertebrates which in turn are eaten by fish and birds.
Branches and trees laying in water can aid flow diversification and again provide safe places for fish and invertebrates as well as a decent perch for a kingfisher. River restoration works often include the installation of large woody debris where a tree is felled into the water and anchored with steel cabling, mimicking natural flow deflectors.
In summers of high temperatures and low water, trees provide vital shade to keep waters cool by around 3° C, helping to maintain oxygen levels for fish and invertebrates. Dappled light with some shade is best, as too much shade can encourage excessive algal growth, especially when combined with nutrient enrichment.
Trees are used in natural flood management (NFM) to slow the flow with leaky dams sited strategically along becks. These create a stepped system; water collects behind the logs and is slowly released through the gaps between the logs. This also helps to rewet upland areas improving biodiversity and acting as temporary storage areas in times of heavy rains and storm events.
Part of the work of the Life R4Ever Kent project will be to restore parts of the River Kent and its tributaries.
We’ve already added some flow detectors to a section of the River Mint. https://r4everkent.co.uk/news/installing-fish-refuges-in-the-river-kent-cumbria/
We will be delivering fencing projects and creating buffer zones, planting them up with native trees. Planting the right tree in the right place is really important too. Choosing native trees helps increase diversity and resilience, choosing to plant a water loving alder by a beck rather than a beech improves survival rates and better growth.
Trees have always been a part of our lives, entwined in folklore and providers of natural medicines. Some trees are iconic; think of the Sycamore Gap, the Major Oak in Sherwood Forest and Old Knobbley in Essex, an 800-year-old oak.
So we have our favourite trees that suit the sites we work on.
Alder (Alnus glutinosa) thrive in wet conditions, are monoecious (have both male and female flowers on the same tree) and a larval food plant for alder kitten moth, the pebble hook-tip and the blue-bordered carpet moth. The catkins are a good source of nectar for bees and seeds from the alder cones are particularly favoured by siskin and goldfinch. Its ability to withstand rotting in water makes it valuable to man.
Downy birch (Betula pubescens) grows well in damper soils and are home to more than 300 insect species. Like other birch they are associated with specific fungi including fly agaric, birch milk cap and woolly milk cap, whilst woodpeckers often choose birch to nest in. In some folklore, birch symbolised renewal and purification, with bundles of twigs used to sweep out the old year, hence besom brooms.
Goat willow (Salix caprea) can live for 300 years and grows well on damper ground. The male catkins are super soft and the one we traditionally think of as catkins as they are just like a cat’s paw. The female catkins which grow on a separate tree tend to be greener in colour and longer.
The leaves are the main food source for purple emperor butterfly caterpillars as well being eaten by a variety of moth caterpillars. Purple emperor butterflies are sadly quite rare and mostly found in the south of England, though they are moving northwards due to climate change.
In medieval times the bark was chewed to release salicin, a compound from which aspirin is derived, to help relieve toothache and headaches.
By Kath Smith, Community Engagement Officer