Humans' Alteration of Nature

In my previous blogs, I have mainly investigated the contributions by climate change to extinction. As my ultimate goal is to find out whether we are on the edge of the sixth extinction, I also investigated other factors; specifically, I researched into the impact on species that is currentlycaused by humans. 

Peter M. Vitousek and his colleagues produced an influential paper on this topic. I find this diagram they created very useful in terms of understanding the contribution by humans to possible environmental changes. Inevitably, humans modify the environment to make possible their developmental plans. Figure 1 is a good summary of the impacts of human actions. 

Instead of summarising the paper, I will talk about land and ocean alterations, as they interest me the most. It is certainly not surprising that land transformation represents the primary driving force in the loss of worldwide biological diversity. There is an extreme case of land alteration, up to 10-15% of Earth's land surface transformed for agriculture or urban-industrial development. Deforestation is one of many reasons behind habitat loss. According to the research conducted by FAO, global deforestation rate has accelerated since 1980. For instance, habitat alterations in the two Brazilian tropical rain forest biomes, Amazonian and Atlantic have led to the alteration of local and regional biodiversity - possibly leading to extinction. Not to mention how land alteration affects climate by directly contributing ~20% to current anthropogenic carbon emissions..

Sumatran elephants are one of the victims of such alteration. The species is now critically endangered, half of its population disappeared, as they experienced one of the highest rate of deforestation in Asia. As natural lowland forest has razed in the past 25 years, nearly 70% of their habit have been destroyed in one generation. 

Humans have been affecting the productive coastal margins in oceans too. This has significant impact, as coastal wetlands are responsible for mediating interactions between land and sea. Approximately 50% of mangrove ecosystems have been transformed or destroyed by human activity globally. Together with unsustainable practices of fishermen, fish that are over-exploited could float towards the edge of extinction. 

Despite all the negative views on human activities, some reckon that actions of humankind can increase genetic diversity through resource alteration and new selective pressures. Moreover, conservation schemes have been implemented to protect endangered species. One quarter of the Brazilian Amazon forests is under effective conservation regimes, up to 70% will be expected to be maintained. Recently, Scottish wildcats are under a new conservation strategy that aim to save them from extinction.

Conservation policies appear, but human development continues. Without doubts wide range of species are still experiencing threats from the human population.