Designing gardens for biodiversity

What principles do we follow in designing a biodiverse garden

At Haddon Studio we follow a number of key principles to maximise biodiversity in a garden - and a selection of these are shared here:

• Healthy soil and water forms the starting point for every design, and so, for example, poisons (herbicides, pesticides, fungicides) are to be avoided wherever possible;

• The old adage that the secret to successful gardening is planting the right plant in the right place underpins everything we do and is set within the wider ecological context of the garden, with plant populations and communities being understood in terms of their interactions which lead to competition or coexistence;

• The creation of structural heterogeneity - achievable through plant diversity, plants of different heights, plants of different forms, and good groundcover - is crucial to creating habitats;

• Equally important, alongside structural complexity, are the eco-tones - the areas where one habitat type merges into another - which are where biodiversity is usually at its highest;

• At the very start we recognise that we are creating a natural system - and one which must be expected to change over time. We will however seek to retain the original intention of the spaces (with our clients playing the continuing role of ecosystem engineer (a title usually used for wild cattle, boar, beaver and elephant) to clear, weed, or ‘garden’ areas so that they retain their structural heterogeneity and the biodiversity this creates);

• Irreplaceable habitat types will always be retained - we would never grub out a traditional orchard to make way for a tennis court, for example;

• When sitting at the drawing board and creating new areas of habitat within a space, priority is given to locally relevant habitat types for the support of locally important species, ensuring that each garden forms part of a web of connectivity across the broader landscape. This prevents a dull monotony of the same species (those best adapted to co-exist alongside our current lifestyles and habits) appearing in every garden;

• During construction consideration to mitigate losses before a completed garden is produced will be assessed and actioned - as a newly planted habitat will never offset (in the short term) a mature and functional eco-system that is removed to create a new wooded area for example;

• Finally, and most importantly of all, a garden must remain an aesthetically beautiful space for the enjoyment of its current guardians as our needs are equally important in the development of the space over the coming years.
  

Our approach to the design of gardens for biodiversity

Above I have written about our biodiversity principles and how these set our intent and guide our practice but in reality it is how we apply these to actual projects that make all of the difference.

Below therefore is an insight into how we approach our biodiverse designs.

We understand the importance of complex, layered planted habitats and eco-tones (the points where two habitat types intersect) and, throughout the design process, we ensure that the changes we make for wildlife are targeted, achievable, and site-specific.

Prior to the design getting to the drawing board there are four tasks we can undertake:

• A desktop survey using readily available satellite imagery. This allows us to see the site within its wider landscape context and look for broad habitat types and corridors between those habitats, to understand the matrix of landscape within which the site sits.

• A study of online resources to identify key habitat types for the region, specific areas of interest and particular species whose numbers could be increased.

• A field survey to locate specific habitats and to identify key native flora and signs of wildlife. We are not ecologists, although we will call them in where required, but we provide enough detail to gain a benchmark for the presence and range of nature in a garden.

• An agreed biodiversity ‘goal’, with the aim of increasing biodiversity in the garden by a minimum of 10%

More detail on creating biodiverse gardens

To provide a little more context on how we design for biodiversity, below are three key areas every designer should consider.

First we start with the basic building block of any garden or landscape - the soil.

The soil is teeming with life and we want to maintain that - indeed a teaspoon of soil can hold a billion bacteria, metres of fungal filaments, thousands of protozoa, a handful of nematodes, and occasionally a giant such as a worm, ant, or centipede.

We will, therefore, wherever possible:

- Maximise open areas of ground and minimise areas of hard landscaping such as paving,

- Work with the existing topography of a site so that we don’t need to move and destroy the structure of the soil any more than is necessary, nor disturb the fungal networks that are key to future plant health and survival,

- Understand, preserve and enhance the soil that you have.

Another fundamental constituent of the garden is water:

- A fundamental principle is therefore planting to minimise water use (especially important as I write this in a drought in summer 2022) - selecting the right plants for your soil type and location,

- If you do need lots of water - for vegetable gardening for example - then water storage is key - and understanding where and how rainwater harvesting will happen should underpin a design at its earliest stages,

- The flip side to saving water is getting rid of unwanted water - for which we can create rain gardens from which storm water can slowly percolate away for example (as it is illegal to direct water from your garden elsewhere - to potentially flood your neighbours).

However it is the plants which are the fundamental building block of any garden - creating a haven for us to enjoy. Plants also form the base of the pyramid of life and the biodiversity of the garden or landscape inevitably stems from plant choice and cover.

To achieve a biodiverse and beautiful garden we therefore need to:

- Ensure a healthy and broad diversity of the right plants are used - plants that will grow in your garden with minimal additional inputs (such as water, fertiliser, or pest control),

- Plant to help connect broad habitat types within the wider landscape - which simply involves looking at your garden in the context of its locality rather than creating it in ignorance of this and drawing the local wildlife and its habitat into the garden,

- Plant smaller plant specimens that will establish better, need less water, and once established will not need regular replacement (although always allowing for the occasional specimen plant to add interest and vertical (or horizontal) structure),

- Cover the soil with plants to avoid erosion and create invertebrate habitats - it is only in the poorest wild habitats that you see bare soil,

- Aim to create healthy and functioning eco-systems - too often what went before is simply a degraded version of what went before that and so simply restoring places misses the intent of reversing biodiversity loss,

- Balance native and ornamental plant choices - assessing our choices for nectar, for aesthetics, and for maximising food plants for the wildlife around us (to give just three examples),

- Work with our clients to view the garden as it is and not a neat and tidy desert, as was preferred 50 years ago - so we will retain fallen leaves and dead wood (to feed the soil and the invertebrates), we will encourage no mow May (to provide nectar and diversity of habitat in the garden), and we will not advise the use of poisons to solve perceived issues,

- Retain established plants where possible - perhaps re-pruning and shaping mature and overgrown specimens to give them a new lease of life.