As pointed out in my previous post, my plan was to jump straight into land use and species loss, but I felt the need to first set out some basics. At first, there might be some confusing as to why I needed to talk about climate change, sea levels and the decreasing pH of our oceans – indeed when one talks about land use and species loss, it’s usually discussing deforestation, degradation of environmental systems and other over-exploitation causes. These problems have made headlines for longer than I’ve been around (with little headway made to reduce our impact as I see it) and are not directly the focus here. Inaction has, without a doubt, been the result of avoidance and profit. Indeed, most people are within driving distance of a reserve of some sort and so feel that there’s a place for the our fauna and flora, however this is even less likely to do over the coming century.
When local is no longer home
According to the number found at the DEH, the Adelaide and Mt Lofty ranges cover 780,000 ha, of which 98,000 ha is remnant native vegetation. Of course this is highly patchy and much of it is land that was of low agricultural or social value. Any local would have also noticed the abundance of exotics – especially olive – in this “remnant” vegetation. My passion as a ecology student was this very issue of islandisation and invasive species, so I’ll have to watch myself here. There has been a lot of work regarding biodiversity and species fitness within increasingly isolated patches of remnant vegetation, which suggests that patch size (Ferraz et al. 2007, and, Helzer and Jelinski, 1999), risk related to migration across inhospitable terrain (Bickford et al. 2010), and a need to address the overall diversity supported by the patch (Franklin, J. F., 1993) are among a number of important factors to species persistence.
As was made clear in the previous post, regardless of the forces (which are hotly debated among the general community), there has been a general and ongoing trend of global warming since the nineteenth century. This trend has noticeably effected and will continue to shift ecosystem function and climate (Traill et al. 2010). Range of many species has tended poleward and upslope as climate shifts to a warmer state (Anderson et al. 2009). Giam at al. (2010) also demonstrated that equatorial regions were at greatest extinction risks due to both climate change and socio-economic factors.
Returning to the Mt Lofty and Adelaide region, as outlined on the DEH website, there are various biodiversity conservation plans and policies aimed to preserve the remnant flora and fauna of the state. This may not do under changing climate factors, with distribution regions no longer suitable for the locals. In previous times of climate change, migration towards or away from poles would encounter only geographical barriers (such as mountain ranges, rivers and of course continent borders). Over the pass three centuries, land-use modifications and invasive species introduction relating to human activity has added to these geographical barriers. Plant distribution, for instance, is unlikely to be able to pass agricultural land – let along suburban sprawl. Feder (2010) and Ferraz et al. (2007) suggest that an individuals ability to survive would rely on being able to move great distances or be highly tolerant to climate change.
Predictions of the changing climate across South Australia (continuing the example) would strongly suggest that a poleward movement would mean that the majority of South Australia’s population (mostly coastal) and agricultural regions become major barriers for migration. As various species of flora and fauna have different potential for migration rate and tolerances to overcoming barriers, it would make sense that such migrations would also upset ecological interactions between species which would logically further increase extinction rates.
With the wild things looking for a more suitable home, it’s pretty evident that soil erosion (such as dry land salinity and acidity), altered water usage and sprawl have far larger effects than have been generally appreciated.