Sustainability in the horticulture department

Though all eyes are on the animals at our Zoos, there is a vast amount of work that goes into the vegetation at London and Whipsnade. Animal exhibits need suitable foliage to create the right environments for particular species, and let’s not forget all the plant matter our grazers get through! The horticulture Department works hard to ensure that the sourcing, growing and disposal of all of this vegetation is as environmentally friendly as possible.

Keeping Chemicals down

Growing the vast variety of healthy plants for all the different species at the zoos, and keeping down unwanted invasives is a challenge. Despite this, no pesticides at all are used on any of our estates, and to keep pests down we use biocontrol, such as lacewing or ladybird larvae to eat pest insects.

Only minimal amounts of herbicides are used as a last resort for particularly resistant invasive species such as Japanese knotweed. These are applied in a very targeted way by injecting them directly into the weed plants, to reduce the amount of chemical reaching the soil. Otherwise, strimming and other mechanical control for weeds is used as much as possible.

Because of the problems that fertilizers can cause in waterways, we keep fertiliser use to a minimum. None of the plants are grown with mineral based fertilisers, that contain unsustainably sourced fish bone and blood, or peat fertilisers, which destroys valuable peat habitats.

Finally, all the tractors and other machinery that needs to be used to take care of the Zoo grounds is run on highly refined non-deisel fuels, that are less harmful to nearby humans and animals, and are less polluting of soil and waterways.

Recycling

All the green waste produced at the zoos goes to good use. Waste wood is chipped to line enclosures and larger logs are piled into logstacks in the grounds to provide homes for invertebrates. The rest of the green waste is given to the Royal Parks Authority, which whom ZSL has a ‘gentleman’s agreement’. They compost it for us, and we then use it for growing more plants.

Water saving

Water is another valuable resource we need to use sparingly. At the moment, we only have a rainwater harvesting system on one plant nursery roof, but this has harvested about 4000 litres of water so far. We do not need to water plants in the grounds much, by choosing species strategically and planting at the correct times of year, as well as relying on plant’s natural resilience.

Procuring plants

It is difficult to find all the plants needed for all the different species at the zoo, but the Horticulture team do their best to ensure new plants are from sustainable provenance and require as little transport as possible. Thousands of saplings of native trees are also grown regularly to make sure the grounds are well vegetated, even if older trees and shrubs die off.

Traditional coppicing methods are used to keep the plants in the grounds producing regular supplies of new grazing material, and the team use plant material grown on-site to produce silage for the winter months. Silage involves the fermentation of plant matter, which produced lactic acid from microbial activity. This preserves the matter well and lactic acid is digestible by animals, providing a nutritious supply of food when plant growth is low.