There is now 7 billion of us on Earth, and our presence have wide-ranging impacts all around the globe. Climate change is arguably the most significant and important global change phenomenon we face, and it has wide-ranging impacts on the distribution of biological organisms. As Earth gets warmer and warmer, species can potentially respond in three different ways: one is evolutionary adaption. This however, because the pace of change is too fast, is only possible for the most quickly evolving species. Secondly, species may move polewards and upwards to colder and colder areas. This response is widely observed, and models predict that it is going to be even more common in the future, therefore affecting current biogeographical patterns. Not all species can however move continually to cooler areas. Some are limited by their dispersal ability, and others face geographic barriers, such as mountain ranges, which prevents them from moving to cooler climates. Mountain dwelling species and those inhabiting polar regions find themselves in yet an other difficult situation, as once they reach the top of a mountain or the northern/southernmost tip of a landmass, they simply can not go further. These species undoubtedly face extinction.
The changes in precipitation and warming patterns are however not homogenous around the globe, and some areas will experience more adverse warming or more extreme precipitation patterns than others. These regions will suffer most from extinctions and will show the greatest biogeographical change. The polar regions for example, the Arctic and the Antarctic, are predicted to warm to a much greater extent than other parts of the world, resulting in more adverse ecosystem effects and more extinctions. However the increased warming in these areas will not only mean that more species will go extinct, but actually polar will be able to support more species rich communities: as permafrost melts, many plants and animals will colonise these areas, and therefore despite the high loss of biodiversity, these areas will see an increase in biodiversity.
Beside climate change of course, many other processes alter species distribution around the globe. One of the most significant other factor, with effects quite different from that of climate change is species invasions and colonizations. With the help of humans, many species are transported all around the world, and if they find suitable habitat, they colonise it. Biological invasions have two major consequences: firstly, invasive species often outcompete or predate on local species, causing a decrease in biodiversity. Good examples are introduction of rats to small islands, where they readily prey on chicks and eggs of seabirds, and cause a dramatic decline in bird populations. The other consequence of introductions and invasions is that 'everything is found everywhere'. If at any location the conditions are suitable for the persistence of a species, it is increasingly likely that the particular species got there with human aid, and will indeed be present at that location. This of course breaks down the regional differences between biota, resulting in more homogenous biogeographic patterns.
To sum up, there are three biogeographic processes we witness today. These are not specific to certain regions, are pretty much observable all around the globe.
1. A trend of poleward and upward movement of species and communities.
2. A trend of decreasing biodiversity, caused by a variety of processes including for instance climate change, habitat loss and modification.
3. Homogenisation of species composition due to species introductions and invasions.
There are a number of issues which I have not discussed on this blog, so there is much more to explore. However the examples I've given illustrate well the kind of changes we are inducing, and the biogeographical consequences these changes have. The list could therefore be continued endlessly, but the major types of effects these processes have has been described and illustrated.
Thank you for following!
Wednesday, 11 January 2012
A General Trend of Biodiversity Loss. What has been done, and what are we to do?
As we see, most anthropogenic processes cause a global decrease in biodiversity. Indeed it has been suggested that we are currently in a mass extinction (The Sixth Mass Extinction) which is comparable to that of extinctions in the geological time. It is sad that this blog can not report on human induced speciaction events. This is partly because the pace of anthorpogenic chagne is not equivalent to the timescales on which evolutionary processes occur. To changes as fast as the ones we witness today, only the smallest species with the shortest generation times can adapt. Insects fo example are famous for evovling resistance to pesticides extremely quicly. Despite it has been suggested that some species may be able to adapt to climate chagne for example, it is unlikelu that such evolutionary processes could significantly alter global biogeographical processes.
From my point of view, there is one crucial difference between the Sixth and the previous mass extinctions. The one we witness today, because it is caused by a conscious animal H. sapiens, it can also be altered by this species. It is down to us wether we do noting, mitigate this extinction, or even reverse it. So what is it that we do to deccelerate the dramatic rate of species loss?
Decade of Biodiversity 2011-2020
United nations declared 2011-2020 the Decade on Biodiversity. The goals of this initiative is to help implementing the Aichi targets, a set of five strategic goals and 20 targets, as agreed by the world's governments at COP10 in 2010. The five stragegic goals are the follwing:
A. Adress the underlying causes of biodiversity loss
B. Reduce pressure on biodiversity and promote sustainable use
C. Safeguard ecosystems, species and genetic diversity
D. Enhance benefits to all from biodiversity and ecosystem service
E. Enhance implementation
Within each of the five strategic goals, there are fou to six targets defining what is to be done exactly to achieve the strategic goal. Clearly goals A B and C are msot important for slowing biodiversity loss. Some of the targets to be achieved under these goals are:
Target 5
By 2020, the rate of loss of all natural habitats, including forests, is at least halved and where feasible brought close to zero, and degradation and fragmentation is significantly reduced.
Target 11By 2020, at least 17 per cent of terrestrial and inland water, and 10 per cent of coastal and marine areas, especially areas of particular importance for biodiversity and ecosystem services, are conserved through effectively and equitably managed, ecologically representative and well connected systems of protected areas and other effective area-based conservation measures, and integrated into the wider landscapes and seascapes.
Target 12
By 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained.
If these ambitious targets are achieved, we may hope that biogeographic processes we witness today will be halted or reversed, and we will no longer live in a mass extinction.
From my point of view, there is one crucial difference between the Sixth and the previous mass extinctions. The one we witness today, because it is caused by a conscious animal H. sapiens, it can also be altered by this species. It is down to us wether we do noting, mitigate this extinction, or even reverse it. So what is it that we do to deccelerate the dramatic rate of species loss?
Decade of Biodiversity 2011-2020
United nations declared 2011-2020 the Decade on Biodiversity. The goals of this initiative is to help implementing the Aichi targets, a set of five strategic goals and 20 targets, as agreed by the world's governments at COP10 in 2010. The five stragegic goals are the follwing:
A. Adress the underlying causes of biodiversity loss
B. Reduce pressure on biodiversity and promote sustainable use
C. Safeguard ecosystems, species and genetic diversity
D. Enhance benefits to all from biodiversity and ecosystem service
E. Enhance implementation
Within each of the five strategic goals, there are fou to six targets defining what is to be done exactly to achieve the strategic goal. Clearly goals A B and C are msot important for slowing biodiversity loss. Some of the targets to be achieved under these goals are:
Target 5
By 2020, the rate of loss of all natural habitats, including forests, is at least halved and where feasible brought close to zero, and degradation and fragmentation is significantly reduced.
Target 11By 2020, at least 17 per cent of terrestrial and inland water, and 10 per cent of coastal and marine areas, especially areas of particular importance for biodiversity and ecosystem services, are conserved through effectively and equitably managed, ecologically representative and well connected systems of protected areas and other effective area-based conservation measures, and integrated into the wider landscapes and seascapes.
Target 12
By 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained.
If these ambitious targets are achieved, we may hope that biogeographic processes we witness today will be halted or reversed, and we will no longer live in a mass extinction.
Tuesday, 10 January 2012
Amphibian Decline and Climate Envelope Modelling
A letter published in Nature two weeks ago expands nicely on two issues I explored in this blog. As I discussed, amphibians are one of the taxa most severely affected by climate change, and it has been suggested that their decline is not only caused by this single factor, but by the interaction of a number of threats including a fungal disease called chytridiomycosis. Holf and colleagues wanted to know how the three major suspected threats, namely climate change, chytridiomycosis, and land-use change may interact in the future to threaten amphibians, and what are the spatial distribution of these threats in relation to amphibian diversity. They used climate envelope modelling to project these threats to the year 2080, and examined weather the most affected areas overlap with species rich areas or with one-another.
Their findings are not too promising for amphibians.
Their findings are not too promising for amphibians.
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