Today, May 22nd, is International Biodiversity Day!
Biodiversity is a word that many have heard of but perhaps may not truly understand what it is and why it is so important. Biodiversity is literally the diversity of life; all the flora and fauna on Earth that persists in its current form through the process of evolution. Biodiversity’s connotation has unfortunately been bogged down by rhetoric- the fate of many environmental concepts these days; overuse and misuse has caused us to be either numb, confused or passive to hearing it. I want to clarify this term and why you should care about it. Biodiversity is both simple and complex at the same time. Simple because when we look around outside, we can see it everywhere- it is the variation in plants and animals that surround us. Some of us may even ponder biodiversity without knowing- why ARE there so many different kinds of deer-like species or tree species or bird species? Are they all so very different from each other that all of them are essential? Biodiversity is complicated because the answer is yes, they are all essential. Biodiversity within an ecosystem- the amount of species that can be found- gives that ecosystem resilience. All these species fill a role in an ecosystem, they all perform a specific role- this is their niche. Some of these roles may overlap slightly, but it is this overlapping that gives strength to the ecosystem. If a natural disaster, like a fire, destroys a lot of a specific species, another with an overlapping or similar niche can compensate. Complexity within an ecosystem is the key to its health and persistence.
Unfortunately, in modern times, ecosystems have more than natural disasters to contend with… humans. Habitat destruction, land conversion, pollution, global warming, and exploitation are some of the main threats to biodiversity. Habitat destruction (e.g. clear-cutting forests) and land conversion (e.g. transforming natural habitat to farmland) are the antithesis to natural complexity; these threats simplify a landscape and make them more homogeneous. Less species equates to less resilience and reduces the overall health and functionality of an ecosystem, as well as its ability to persist through perturbations. Not all trees are created equal- think of a pine plantation (same tree planted in neat, organized rows) versus a rainforest (a seemingly chaotic array of hundreds of species of trees)- they both may have a similar number of trees, but they differ vastly in their composition and thus, their ability to support life. The diversity of trees within a rainforest will always be able to sustain many more species than a monocrop plantation as there will be available niches for species to fill. In a homogenous landscape, if a few species are lost, the entire system can collapse, but in a heterogenous landscape, the system can cope with losing a few species because it is more resilient and other species can help fill those lost niches.
It is widely recognized that climate change and biodiversity are interconnected. Climate change can be thought of as an ecosystem perturbation on a grand scale. As our climate warms, ecosystems with more resilience (i.e. more species) can adapt better and more quickly to a changing climate. A changing climate can also intensify natural disasters, like floods and fire, which impact species persistence (e.g. species with a small range can become extinct during an intense hurricane). Climate change is impacting unique or specialized species unequally (e.g. polar bears and amphibians) because these species have small or distinct range requirements and they cannot adapt fast enough to cope with the changes. Remember, these species adapted under conditions that took millions of years and our climate is changing at a much faster pace.
Besides the intrinsic value of life- the value that cannot be measured monetarily-biodiversity also contributes to our economy by providing essential ecosystem services for free. These services include pollination, medicine, water purification, storm surge protection and nitrogen fixation. These free services have been estimated at $33 trillion a year. They are all under threat as we lose biodiversity and our ecosystems become more simplified. Evolution has engendered biodiversity and this complexity is how life has evolved and finds balance; its importance to ensuring stability cannot be overemphasized. Unfortunately, science and politics have been clashing in our society in a way that marginalizes this message. It’s not political at all- as stewards of the planet, biodiversity is our inheritance, our legacy and the very reason for our existence.