The merits of planting native species

[Back]

In terms of biodiversity, I assume if you took an average garden and replanted it with native plants, other species (esp. fungi and invertebrates) would increase in numbers and variety. I'm talking about replacing like for like. For example, a small ornamental tree might be replaced with a native birch. The herbaceous border might now include stinging nettles and native thistles.

Am I right in my assumption?

Does anyone know of any studies that have been done?

[nightshade]

To win back Sparrows I have replaced a lot of my garden with native species and as a result now have Sparrows in the garden again but they do love the Bamboo Niger which I suppose stands instead of reeds

[Cotham Marble]

Originally Posted by Back

In terms of biodiversity, I assume if you took an average garden and replanted it with native plants, other species (esp. fungi and invertebrates) would increase in numbers and variety. I'm talking about replacing like for like. For example, a small ornamental tree might be replaced with a native birch. The herbaceous border might now include stinging nettles and native thistles. Am I right in my assumption? Does anyone know of any studies that have been done?

I don't know of any studies that deal directly with the comparison of native versus non native in gardens. I do think that there may be a difficulty with achieving a meaningful statistical analysis that would demonstrate the difference unequivocally. Garden (to invent a mass noun) is not an expansive space - unlike moor, or pasture or forest, and it is these expansive areas measured in hectares or square kilometres which underly current understanding of UK ecology and levels of biodiversity. Certainly changing plant species in a garden will change the resident and visiting fauna, but whether within the limited area of an average UK garden this will of itself increase diversity or total faunal number within the garden may be a highly problematic question.

Part of the problem relates to the character of 'garden' - something which by its very nature is a highly managed space, created to meet the needs of the flora planted in it. The management of a traditional style herbacious border with regular soil disturbance and nitrogen inputs would suit nettles - but not many other native plants. Many plants of the average border are high necatar producers important for bees and the replacement with nettles and thistles would see a loss of bee numbers, though the number of buttlerflies and moths would likely.

A very particular challenge arises when trying to replace the many low growing abundantly flowering exotic shrubs that form the basis of much UK garden planting. There are very few equivalents to valuable invertebrate supporting plants such as escallonia, buddleia, syringa etc. and this limits the capacity to replace on a like for like basis, and to maintain nectar sources available during the summer months a move from shrubs to perennials would be required. Such a change might be desirable, but it might also reduce the attractiveness of the garden to bird species throughout the year as taller cover would be reduced.

On balance, and only IMO, I think that a move toward increasing use of native species in a garden is desirable, especially the use of native perenniels, but I think any net benefits probably result from replacing monocluture lawn and hedging with a mixture of species, rather than any simple swap between native and exotic.

CM

[Susie]

I can't think of a native plant that beats vebena bonariensis for attracting butterflies late in the season.

[Back]

Thank you for your replies

NS - hawthorn is definitely one I want to grow.
CM - thank you for giving me so much food for thought! Interesting post.
Susie - another for my wish list .

On balance, it seem that both natives and "exotics" have their merits. So a mixture might be desirable? I will give it some more consideration.

[Susie]

A mixture is what I have and it seems to work well. I find the thing to do is to steer away from any plant which has been 'over developed'. The hybrids and sterile plants and particularly anything with double flowers are a no no.

The mediterrean herbs are very popular and now we are even getting the mediterrean pest species turning up, such as the rosemary beetle, i suppose one can claim they are a larval food plant too!

[Malcolm Fraser]

There have been some studies - the Biodiversity in Urban Gardens or BUGS projects.

You can read the papers here:

BUGS projects - introduction

Or seek out Ken Thompson's book - "No Nettles Required - The Reassuring Truth About Wildlife Gardening " - for a very enjoyable retelling of the findings.

One of the main findings is that, in gardens, exotic plants are just as good as native plants for biodiversity, if not better. Which stands to reason if you consider that most invertebrates are generalists not specialists.

[charlieb]

Originally Posted by Susie

I can't think of a native plant that beats vebena bonariensis for attracting butterflies late in the season.

But it ain't no good for the caterpillars

[Susie]

Obviously, which is why it makes sense to plant both sources of nectar for the adults and larval food plants.

[Back]

Hi People, thanks again!

Good larval food plants anyone (I have some garden space of my own at last, so I can buy/sow/plant now )?

Thank you very much for the references, Malcolm,

Bev