Biodiversity (I can't think of a clever title for this one)

The Importance of Biodiversity and Global Trends

Ever wondered what's happening to all those animals, plants, and creepy crawlies living in the Amazon? Not to be all doom and gloom, but our 'burn everything!' approach to land clearing is kind of screwing them over... just a little bit. I've made no secret of this and have explicitly stated in previous posts that many species native to the Amazon Rainforest are under threat. "But, what's really happening?", I pretended to hear you ask! Well, that's what I'm here to tell you; whether you asked for it or not. Be educated, my reader(s)!

A brief note before we begin; I will be splitting the biodiversity post into two since it would otherwise be too lengthy. This post will cover global biodiversity trends and the importance of biodiversity as a concept. The next post will focus specifically on biodiversity in the Amazon in regards to these ideas.

Ecosystem biodiversity, which is sometimes referred to as genetic diversity, is analogous to the species richness of an ecosystem. That is, the number of different species co-existing and living per unit area (Encyclopaedia Britannica, accessed 2018). Basically, it's just how many different kinds of organisms there are. Although simple, it's an important concept and is important in maintaining ecosystem functioning, which provides goods and services to human society, such as freshwater filtration and raw materials. Yep, biodiversity is economically valuable as well - remember this! High biodiversity rates have been shown to increase ecosystem productivity and nutrient retention rates, make ecosystems less susceptible to invasion by foreign species, and somewhat mitigate the negative impacts of environmental disturbances (Hooper et al., 2005).

Experimental work by Balvanera et al. (2006)  spanning 50 years has shown increased biodiversity to have a net positive effect, although this is stronger on the community-level, where populations are smaller, than at the ecosystem level. Balvanera et al.'s study also indicated that biodiversity has a greater positive relationship with ecosystem productivity than ecosystem stability.

Figure 1 from Gamfeldt et al. (2008) below conceptualises this relationship well, where species richness is biodiversity. The black and grey lines show the result of changes in species richness with ecosystem functioning for high and low redundancy ecosystems. In high redundancy ecosystems, there are a number of species capable of filling a specific ecological niche that results in a specific ecosystem function. The high redundancy scenario in this case shows the maximum loss in functioning where the species lost are those most efficient at filling their ecological niche. With high redundancy, you would expect functioning to remain higher than with low redundancy, since multiple species are able to fill the same niche in the former, despite the most efficient species being lost. The general trend, however, is that ecosystem functioning remains higher under higher species richness across both redundancy levels. Ultimately, high levels of biodiversity prevent ecosystems from tipping into unenviable states.

Figure 1: The relationship between biodiversity (species richness) and ecosystem functioning is neatly conceptualised, distinguishing between the degree of relationship in high and low redundancy ecosystems. (Source: Gamfeldt et al., 2008)

Knowing that biodiversity is important, it's been monitored and studied extensively on a global scale. A landmark study by Rockström et al. (2009) defined nine planetary boundaries that humanity can safely operate in. Johan Rockström himself did a TED Talk on the topic, which you can find here, in case you're interested! It is suggested by Rockström et al. that transgressing these boundaries could bring about abrupt and potentially irreversible environmental shifts. Biosphere integrity, aka biodiversity, is one of these, and has already been exceeded on a global scale. Figure 2 illustrates this, where the threshold for biodiversity is shown as extinctions per million species-years (E/MSY). It's not surprising that this planetary boundary has been breached, considering that ongoing patterns of biodiversity loss have contributed to the first anthropogenically-driven major extinction event ever seen on Earth - and only the sixth ever event (Chapin et al., 2000).

Figure 2: The nine planetary boundaries as defined by Rockstrom et al. (2009). Four of these, including biodiversity (shown here as genetic diversity), have already transgressed into the 'zones of uncertainty', where there is a high risk of potentially irreversible and abrupt environmental shifts to undesirable states. (Source: Stockholm Resilience Centre, accessed 2018)

So, it looks like loss of biodiversity is currently, and will continue to be, a major problem and we have a good idea about how this might affect ecosystems globally. We know it's not going to be good. But the studies I've presented so far have alluded to an economic impact as well, since ecosystems provide us with a number of goods and services (Gamfeldt et al., 2008). Anyone know of a tropical forest that's being carelessly exploited for economic gains?

Oh, that's right... The Amazon Rainforest! Of course, the Amazon is not exempt from this issue. Nothing is ever so easy! But I'll be ending this post here and continuing on with the Amazon in the next one, as promised at the start of this post. See you soon, dear reader(s)!