I recently listened to a radio programme on Radio National (ABC radio) with Dr Michael Dunlop, of the Ecosystems Sciences Division of CSIRO, in Australia. The CSIRO were conducting habitat modelling to uncover the extent of biodiversity change in Australia. There seems to be a real shift in approach as to how we frame the debate about habitats and preservation of species. Individual species have up till now been the focal point when reading articles about bio-diversity, for example, one reads about the plight of the orange bellied parrot or the brush-tailed rock wallaby. One also reads about what action is being taken by government and local groups to counteract damage to habitats, such as damage caused by introduced species. But despite the efforts of conservationists, climate change caused by humans, and fires, disease and other more natural processes are a reality. Loss of species (or their relocation) in Australia will be ‘significant’ by 2030 and ‘extreme’ by 2070. According to Dr Michael Dunlop, we have to accept the emergence of new species and habitat types in the Australian bush, as an inevitability. So it seems land management and research is going to be less about maintaining current species and more about helping biodiversity to adapt. This means huge attitudinal change. Are conservationists ready to rethink their modus operandi? Will they simply learn to adopt a ‘landscape as a whole approach’ (rather than focussing on a single species, such as, the southern hairy-nosed wombat as discussed on ABC News)? As climate and habitat modelling becomes more complex, the job of ecosystems and biodiversity scientists is going to become very complex, indeed!
The CSIRO report leads me to consider whether all cycles in our environment are inevitable? I don’t think so. What about in the case of our urban landscapes? Here change is brought about after lengthy planning submissions and long-winded town-planning processes which vary depending on the municipality, region, state and country in which we live. Species are disappearing and habitats are diminishing in cities for completely different reasons from those operating in the country – fires, climate change, invasive species and more natural processes. In cities, it’s us humans who are radically changing our green wedges and urban interfaces with nature.
Because we see the country and cities as distinct, we exaggerate these distinctions more; extending our urban boundaries, building more roads, and increasing urban density. We don’t pay heed to the many elements that cities and country do have in common. Instead, we frame ‘nature’ as being out there, somewhere else. Look around you; nature is under our feet, in our gardens, in the air we breathe – everywhere. From rural land management principles we can learn why it’s important to protect topsoil and retain native species to support complex local ecosystems. We can learn so much about invasive species from our experiences in the country with weeds and introduced species, which are affecting food production as they affect urban biodiversity.
For example, we learn from nature about the way rain falls, and how the ‘catchment’ on which rainwater falls is so important to our wider environment. Rainwater will either percolate back in to the top-soil and leach deep in to the groundwater or streams, and be absorbed by plant-life in the form of evapo-transpiration, or it can run off in to storm-water systems, creeks and seas. In the undisturbed, natural environment higher volumes of water feed back in to local ecosystems, whereas in an urban locality we see much larger quantities of storm-water running off and entering our waterways and leaving the local environment. Why? Man-made (hard) surfaces such as (non-permeable) concrete (footpaths, public spaces), bitumen (roads) and the persistent building up of our homes and backyards (outdoor rooms) cause the water to run off. The popularity of the outdoor room (where householders build kitchens, dining rooms and general entertaining rooms in their backyards) has really taken off. The amount of hard (non-porous) surfaces we build, both in public and private spaces, are having a huge influence on the local ecosystem, including:
1. Our waterway health. These are the nutrients, pathogens, hydrocarbons, sediment being washed into drains and impacting waterway wildlife and ecosystems in creeks, and oceans – such as, blue green algal blooms which can cause huge problems for fishing industries and local tourism. When we leave the soft surfaces (trees, shrubs, herbaceous perennials, grasses) in place, these absorb so much of the stormwater, as happens in the more natural setting, and for this reason, rain gardens, swales, biofiltration trenches and wetlands are now being installed by local governments and private developers in Australia, and throughout the world, to counteract the pollution and sediment which otherwise would reach the waterways. Water sensitive urban design is a means of ‘putting back nature’ in those urban spaces where it’s most needed.
2. Local temperatures. As we remove planted areas and build up our urban backyards and public spaces this causes an urban heat island effect. By returning natural turf and plant species to these areas, and by constructing green roofs and vertical walls, we can naturally cool built up areas in the summer time. If you live in hot, arid or temperate areas like most of Australia, this is vital.
3. Local species. With over-development, local wildlife species have less reason to populate an area because plant-life and habitats are scarce. With diminished plants awaiting pollination and supplying nectar and seeds for birds and insects, the whole cycle of life is interrupted. By observing these cycles in nature, we can help urban forests (including food forests), gardens and parks to best mimic nature.
4. Topsoil disturbance and reduced soil surface. Biota, most commonly found in topsoil, can help plants to grow, attracting bugs which nourish the soil as part of the evolving cycle of life. When we over-develop our backyards this cycle gets disrupted. Large hard surface areas bring increased storm-water runoff, leading to a reduced opportunity for ground-water replenishment causing house walls and foundations to crack.
We can design in more permeable surfaces and practice erosion and sediment control, so that our topsoil is protected, and our ground-water can replenish. We can reroute storm-water run-off (sediment, fertiliser, contaminants) away from drains and back on to our gardens; acting as a bio-filtration medium. We can keep the integrity and diversity of habitats: plant-life, insects and birds in our midst, on which produce gardens and nature as a whole rely. We are seeing all kinds of new gardening crazes: community gardens, verge and street planting, vertical food gardens, and a better understanding of water sensitive urban design. These are just some of the ways that humans are applying the lessons of nature, and putting back what we tend to take out.
I am just touching the surface of the processes at work in our urban landscapes. These man-made processes that we allow to happen are within our control, and are not inevitable, in the way that change may now be in the country. Unlike habitat change in the wider rural setting, our built environment doesn’t have to be on a ‘runaway’ path. It’s just something we can plan so much better.
Urban landscapes just need inter-disciplinary consultation, good planning and design. As scientists are researching broadly across the widest possible biodiversity spectrum, there needs to be a mindshift amongst urban landscapers, town-planners, engineers and WSUD experts (resources willing!), as well. With that comes better communication, research, sharing of ideas and more effective strategies across all land management practices.