Those who plant and protect trees know the vital role trees play in our towns, cities and landscapes, and this is increasingly recognised by decision-makers. DEFRA is halfway through its Big Tree Plant, which aims to plant a million trees by 2015. A handful of UK cities have pledged to increase canopy coverage in urban areas – London hopes for a 5% increase by 2025, Bristol an impressive 30% increase overall. Natural Resources Wales has undertaken the Wales Urban Canopy Cover Study, which it is hoped will inform how much more needs to be planted and where.
Not only do trees have a cooling effect on their immediate atmosphere, play an important role in flood prevention and have a positive effect on health and wellbeing, they also play an important part in healthy, resilient landscapes.
Biochar, a fine-grained and highly porous form of charcoal used as a soil amendment, is made by kiln-charring woody waste at a low temperature with a restricted supply of oxygen – a process called pyrolysis. As well as being an effective growing medium, it improves soil structure and helps soil hold on to moisture and nutrients.
Biochar has also been shown to improve the health and survival rates of newly planted trees, helping more of them establish and thrive. Over the 2012/2013 growing season, Bartlett Tree Experts conducted biochar trials at their research centre in Reading University. Their team planted horse chestnut and beech hedging in a biochar complex from UK biochar company Carbon Gold. The trials replicated stressful conditions typical in tree transplanting, where trees were subjected to significantly reduced root systems before replanting. Some trees were planted with Carbon Gold’s Tree Growth Enhancer, a formula in which biochar is enriched with mycorrhizal fungi, seaweed and worm casts.
Launched this autumn, Carbon Gold’s biochar-based tree care products suitable for all new and established tree types, bare root stock, shrubs and hedging. Its enriched formula of biochar, mycorrhizal fungi, seaweed and wormcasts promotes the quick establishment and reduces losses, encouraging vigorous root growth and healthy soil biology. It also helps retain moisture, minimising plant stress at times of drought and helping to reduce the need for watering.
Carbon Gold’s Craig Sams said “We value working with Bartlett on this important research. £600 million is spent on planting new trees across the UK every year. Each year a quarter of these dies and are lost, costing the industry £150 million per year. Carbon Gold’s biochar could significantly reduce these tree losses.”
Trees have an important role to play in our landscapes. For those responsible for planting or protecting them, biochar is a practical way to help newly planted trees establish well and stay healthy for longer.
