Flowers on the South Downs

Took a walk up the common on the weekend. The viper's bugloss looked wonderful.

 

The value of non-native plants for wildlife gardening

Researchers say there is now enough evidence to conclude that non-native plants are a key component of wildlife conservation in gardens.

The use of non-native plants in gardens is one of very few wildlife gardening controversies. Although many sources state the importance of native plants, it is becoming clearer that non-natives play a key role in maintaining biodiversity in the garden.

Many of our native pollinators have evolved almost in tangent with our native plants. Sometimes the association is so strong and the pollinator becomes so selective that simply no other plant will do. Many butterflies do this, including the Adonis blue on horseshoe vetch. In these cases native plants are essential for conservation. However most of the pollinators you see in your garden are generalist species, which means they can switch to whichever plant is providing the best source of nutrients. When I talk about non-native plants, I don’t mean invasive species (Japanese knotweed, Himalayan balsam, etc), which should clearly not be planted. I’m talking about buddlejas, salvias, lavenders, wild marjoram (from the Med!) and other common resource-rich garden plants, which actually provide a greater quantity of pollen and nectar than some of our native species.

Doctor Ken Thompson from the University of Sheffield and Stephen Head, an Environmental Consultant have reviewed many pieces of research on this topic (read their review here:http://wlgf.org/linked/native_or_non_native_text.pdf) and pointed out that the distinction between native and non-native plants is not as clear-cut as it might seem. True native species are those that evolved or arrived in an area without human intervention. Most of ours would have arrived shortly after the Ice Age. Then the first plants humans introduced were by Neolithic farmers, which means the original non-native species have already been here for roughly 5000 years. Plants have been arriving in Britain steadily since then. Today, there are 1,798 non-native plant species naturalised (surviving in the wild) in England and substantially more in gardens (Hill et al, 2005). I would argue that when it comes to preserving our traditional British landscape and catering for those specialists pollinating species, native plants are very important, however non-native species shouldn’t be cast aside in the urban environment.

Gardening is inherently wildlife friendly. Telling someone the only way to attract wildlife to their garden is to grow lots of native species is not only completely un-evidenced, it will also alienate those who like exotic species in their garden. As Dr Ken Thompson rightly says: ‘If typical gardens are indeed valuable for wildlife, then all gardeners can aspire to bring a concern for wildlife within the various aspirations of their own gardening.’

I personally love native species because I love a wild look in my garden. If I choose a non-native, it’s because it looks English, like wild marjoram. It’s worth remembering that without a good selection of non-native species (and cultivars!), our gardens would have a much shorter flowering season and quite a bit less colour, which neither us or the bees would be keen on.

So to conclude I would suggest when choosing plants for your gardens this year, don’t worry too much about their origin, because most pollinators don’t mind too much. Choose flowers which look natural to you, i.e.: not double flowers or complex hybrids, and most importantly, go for plants you like. It’s your garden after all!   

References: 

Hill,M. et al (2005) English Nature Research Reports. 662: 81

And now we're up to date...

Now that I've posted up a few photos from previous years, I'll introduce the project. My name is Joanne, I'm a postgraduate student at Brighton University, and I study the value of urban gardens for the conservation of pollinators.

Before I started this research I was interested in creating habitats to encourage garden wildlife, particularly wild pollinators. I had known about this medium sized scrap of land just outside Lewes in East Sussex, roughly 400m2, where some old farm buildings had previously stood and very close to a house some of my family rent. In 2013 I was given permission to do a bit of clearing and gardening on this area.

This photo doesn't show the whole plot, but it's the area I initially started on. It was taken in the spring, in the summer the patch is normally chest-high with stinging nettles and thistles, both of which are really important for pollinators, small tortoiseshells for instance. So I've never intended to take back all them, and two years on there's still PLENTY of nettles at the back and in the woodland section to the left in the photo, and the thistles have remained a feature in the flowerbeds I planted.

Plant selection

The site is surrounded by farmland and many species-rich hedgerows and verges, so my intention was to plant lots of pollen and nectar-rich species, but also let any wildflowers in the seedbank establish.

As a general rule I follow two plant lists (I'm not a huge fan of plant lists for pollinators, perhaps I'll do another post on that, but when I started this project I needed some reference point), the RHS Perfect for Pollinators and, more recently Plants for Bees, by Kirk and Howes. Occasionally I've been given plants to put in, but generally speaking all of the plants that are now on the patch are ones that have been shown to attract pollinators.

Having now studied plant selection for my masters degree, I know more about which plants to pick, and I'd say roughly 80% of what's growing there now has been grown from seed.

 In the background: borage, ornamental poppies, ragwort and in the foreground: rose campion, cornflower and calendula.

Cornflower

 One of my favourites on the patch - cardoon.

Trees, bees and butterfies on Ditchling Common

Some snaps of mahonia in the late winter

Absolutely thrilled with the solitary bee house

Managed to catch some pictures today of the solitary bees making their homes on the wildlife patch :)

Designing the perfect home for solitary bees

Unlike a conventional bug stack, a solitary bee house should be built off the ground in a place that will stay fairly dry all year. These bees lay their eggs in holes in walls or wood and plug it up with food for the larvae when they hatch. These bees come in a variety of sizes so different shaped holes are important. The holes must be deep enough to prevent a skewed sex ratio of males being born. Also consider mesh or adding a lip to the outer rim of the house to discourage birds from eating the adult bees coming and going.

With the intention of encouraging as many species of bee as possible I did a bit of research on the optimum size and shape for these houses, since it appears many of the varieties you can buy in the garden centres are not deep enough. According to the papers published so far, holes in wooden blocks should be drilled at the correct depth to keep a healthy brood of young bees. Between 4 and 6mm diameter and 90mm depth is best for many species. Bamboo canes should be cut 170mm deep.

So here's the building process from start (October 2014) to finish (April 2015). As of today, ten nests have been constructed in the bee house :)