Biodiversity Loss

Contents of this page

Introduction
Biodiversity status and trend
Causes of biodiversity loss
Beyond species diversity
Concusion

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Introduction

Biodiversity is the amazing variety of the earth's living organimsms, within species,among species and among ecosystems alike (MA 2005, CBD 2006).
Planet Earth is estimated to host between 5 and 30 million species out of which merely 2 million have been described as yet (UNEP 2007). Known species vary magnitudes of orders in size and show tremendous variation in form and function (Peters 1993, Niklas 1994, Brown & West 2000).

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Biodiversity status and trend

Species extinction rates have increased by as much as 1,000 times background rates and are projected to rise futher by a factor of ten until 2050 (MA 2005). It has been claimed though, that we have entered the sixth mass extinction (CBD 2006).
Despite the substantial progress been made with the coverage of protected area the trend has not slowed down nor has it been stopped and it is becoming clear that the "2010 Biodiversity Target" will not be met as a consequence of an overall inadequate policy response (Djoghlaf 2009).
Results of the IUCN Red List 2009 confirm that 21% of all known mammals, 30% of all known amphibians and 12% of all known birds are now threatened with extinction.
The 1997 IUCN Red List of Threatened Plants (Walter & Gillet 1998), the only comprehensive listing at global scale to date, reveals that 12.5% of all vascular plant species are under threat to go extinct.

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Causes of biodiversity loss

Demographic and economic factors represent the two most important root causes or indirect drivers of biodiversity loss (MA 2005, Figure 4.2 in CBD 2006). The growth of the human population leads to higher demand for food and - possibly to a lesser extent - for energy. The growth of the global economy, on the other hand, gives rise to a higher consumption per capita of energy and - possibly to a lesser extent - of food. As long as science and technology impinges on the efficiency of resource use in production, they do have a negative effect on biodiversity, as well.
The direct drivers of biodiversity change and how they are influenced by indirect drivers is shown inTable 1 (dadopted from MA 2005, CBD 2006).

Table 1: Direct drivers of biodiversity loss

Direct driver   Impact on biodiversity   Under influence of indirect driver   Reference 
Land-cover change, habitat change   very high   Demand for food (very high), demand for energy (moderate)   MA (2005), CBD (2006)  
Nutrient loading & pollution   high  Demand for food (high), demand for energy (moderate)   MA (2005), CBD (2006)  
Overexploitation  high  Demand for food (high), demand for energy (moderate)   MA (2005), CBD (2006)  
Global climate change & rising atmospheric carbon dioxide levels  moderate, increasing  Demand for energy (high)   Thomas et al. (2004) 
Invasive alien species  moderate    Sala et al. (2000), Thomas et al. (2004), MA (2005) 

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Beyond species diversity

Ecological communities, the complex organismic networks that are formed by species interaction are increasingly recognized as being the most diverse component of biodiversity (Ohgushi et al. 2007) .
Thompson (1996) even coined the term "interaction diversity". Although ecology is defined as the science that investigates how organisms interact with each other and with their environment, intercation diversity tends to be the least investigated and least understood component. For instance, Fath & Patten (2000) report on a review of 1,235 articles published in Ecology between 1981 and 1990 and almost one thousand of those dealt with four or fewer species. The sophisticated methods to study species interactions available to empirical ecologists, such as spatial pattern analysis (Dale 2000), path analysis (Morin 1999) and network analysis (Pascual & Dunne 2005), are of rather limited usage in the realms of biodiversity research due to their large rresource requuierments.
This is staggering, since organismic networks are, in fact, the integrated parts of ecosystems, which provide ecosystem functions and are of great aesthetic and econmic value to humans (MA 2005).
Since Schulze & Mooney (1993) published their book "Biodiversity and Ecosystem Fucntion" the topic has attracted the attention of ecologists worldwide. In a long series of experiments empirical ecologists have tested hypotheses and aimed to elucidate how close and stable the relationship is (see Naeem et al. 2009). However, despite the progress that has been made the debate, whether the observed effects were merely a result of experimental artefacts, is still going on (Naeem et al. 2009).

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Conclusion

Fig. 1: Graphical Summary of Biodiversity on Earth


We are in a phase of an alarming, unprecedented loss in biodiversity on earth.
A graphical summary of the main aspects related to the global biodiversity loss is given in Figure 1.
It is stressed here that empirical ecology has fundamental deficits concerning investigation of biodiversity effects at the community and ecosystem scale.
Although ecological modeling has been less involved in biodiversity research, it is my strong belief, that the especially-designed UIBM will contribute to our understanding of biodiversity at the community scale and beyond.

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Copyright Nov. 2009 Dr. U. Grueters


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