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Tips for gardening for biodiversity

Cape Town – Pioneering campaigns to promote gardening with wildlife in the 1980s were transformed into calls for urban biodiversity in the early 1990s. Studies conducted on green spaces in Sheffield, England, revealed that the greater the biodiversity, the greater the psychological well-being of the city’s residents.

In 1993, the UN proclaimed May 22 as The International Day for Biological Diversity (IDB) to increase understanding and awareness of biodiversity issues. Since then, it has become increasingly apparent that cities with high levels of biodiversity attract ecotourists, have happy residents and thrive as top ecotourism destinations.

Just over 50 percent of the global population (3.6 billion people) live in cities which take up just three percent of the earth’s terrestrial surface area. Ranking the levels of indigenous biodiversity in the world’s top biodiversity cities, and quantifying the levels of their governance and management of biodiversity, became a big focus of attention in the 2000s.

In 2008, the parties to the Convention on Biological Diversity (CBD) established the City Biodiversity Index, a protocol for the evaluation of urban wildlife.

Four years later, in 2012, the CBD launched Cities and Biodiversity Outlook, which promotes the links between urbanisation, biodiversity and ecosystem services.

The link between biodiversity and ecotourism is not disputed and world interest in cities with inhabitants that value biodiversity is highly valued by ecotourists. Researchers have also pointed out that the proximity of a city to a national park or a protected area contributes greatly to a high biodiversity index world ranking.

The Sanjay Gandhi National Park in the centre of Mumbai, the Südgelände Nature Park in Berlin, Germany, the Saguaro National Park near Tucson, Arizona and the National City Park in Stockholm, Sweden are international examples of cities with high biodiversity rankings.

The proximity of Nairobi National Park just a few kilometres from Kenya’s capital and the location of our own Table Mountain National Park are the best African biodiversity-rich urban areas.

Other top biodiversity-rich urban areas vying for top biodiversity rankings include Curitiba (Brazil), Joondalup (Australia), Edmonton and Montreal (Canada), Brussels (Belgium), Nagoya (Japan), Paris (France) and Singapore.

Gardening for biodiversity

How can you contribute to the biodiversity of Cape Town and raise the city’s international index ranking among the top biodiversity-rich urban areas of the world?

“Every gardener should take responsibility for their patch of land and we need to guide gardeners towards developing a haven for a wonderful variety of bird and insect life”, says landscape designer Jo-Anne Hilliar.

“The key to biodiversity is to first remove invasive species from your gardens and replant with species whose populations have been reduced by problem plants. Invader species pose a serious threat to ecotourism, disturbing the ecological balance and spoiling the scenic beauty of these tourist attractions”, she adds.

Pallisade fences

Environmentalists also offer a host of ecological reasons as to why palisade fencing – both for security reasons and biodiversity – is a far better option than solid white walls which is likened to having a huge fridge in the garden.

With pallisade fencing, micro- garden wildlife is able to move freely through fencing which promotes the general biodiversity of the area. Plants also have space to spread through the fence.

Water in the garden

A wildlife-friendly pond in your garden and an understanding of the role insects play in maintaining the health of your garden is the key to a biodiversity-rich garden.

Consider these facts:

* Moths provide an immeasurable food source for birds and geckos.

* Ugly worms in your peach tree will emerge as delicate garden Acraea butterfly.

* Amaryllis borer caterpillar is a moth larvae, full of protein beneficial to birds. To keep them away from your clivias, plant a big clump of indigenous Albuca altissima, which is the favourite food of this larvae and will to lure them away from your clivias.

* The praying mantis helps to control garden pests such as worms and moths.

* To attract butterflies to your garden, group nectar plants to obtain maximum allure in a warm, sunny spot protected from strong winds. Then plant up two levels of flowers, one at ground level and one at approximately 1m high – as butterflies show distinctive feeding height preferences. Include an attractive “bath” of damp mud in your garden, which will lure many butterflies who suck at it for essential minerals.

Plant these nectar attractants:

* Low plants: Alyssum, marigolds, lobelia, pennyroyal, phlox.

* Medium flowers: Lavender, wild scabiosa, impatiens, wild statice, oreganum.

* Shrubs: Poinsettia, pentas, agapanthus, buddleja, rosemary, bougainvillea.

* Plant larval host plants for these butterflies: Asclepias for the African monarch, Kiggelaria africana for the Acraea, indigenous members of the citrus family for swallowtails, indigenous figs for the fig tree blue, Dischoriste depressa for the yellow pansy, plectranthus for the garden commodore and Ehrhata erecta for the Table Mountain beauty.

* Animals that may take up residence in your pond include frogs and toads, birds, waterboatman – a predator beetle that swims upside down in the water and stabs its prey, water beetle larvae, dragonfly larvae which prey on minute insects, pond snails which feed on algae and minute insects and diving beetles.

* Avoid adding fresh tap water to the pond. By doing so, you are introducing undesirable chlorine and other chemicals into the water. Rather pipe or direct the rain water from gutters directly into the pond. Any excess rain water can overflow into a bog or marginal area.

* Good plants for ponds:

* For water filtration: Reeds and restios (Chondropetalum tectorum and Elegia capensis).

* Decorative marginal plants: Arum, crinum, crocosmia, scarlet river lily gomphostigma, red hot poker.

* Aquatic plants to provide oxygen: Indigenous water lilies (Nymphoides species).

Weekend Argus