The Nature-Nerd Nuts & Bolts of Biodiversity

Nurturing Interdependence

Nothing has grown more peace in me than the reflections of biodiversity. Here’s a little more about it as a foundation to all of nature’s mirrors:

Biodiversity “refers to the variety of life on Earth at all its levels.¹” It is one of the most essential components to healthy ecosystems as it regulates and reassures that all the functions of the ecosystem are met in balance. Just as individual cells contribute to organs of a body, and just as the organs contribute to the overall function of the being, everything in an ecosystem functions interdependently. In ecosystems, the different jobs that each species performs are referred to as ecosystem functions².

Every ecosystem needs the same jobs to be filled, including:

• Clean water (which requires water movement, retention, and purification)

• Healthy soil (which requires soil formation through decomposition, and soil stability through erosion control)

• Pure air

• Food (which depends on the healthy soil, water and air)

• Shelter from changing weather

• Climate regulation

• and Disease regulation

With all this in mind, no one species can fulfill all the functions of an ecosystem any more than any one organ can keep the whole body alive; they each play their own part. Biodiversity strengthens the power of the whole by ensuring that all necessary parts are fulfilled under constantly changing conditions.

To better understand how biodiversity works, let’s first look at its three different categories:

Genetic diversity refers to “the biological variation that occurs within species. It makes it possible for species to adapt when the environment changes.³” It’s the foundation for all evolution. This is the kind of biodiversity that’s looking at DNA and genes within each individual species; it’s the science behind why we shouldn’t do-the-thing with our own family. This level of diversity is important because it explains how species under threat (meaning that the overall number of them is declining), become less resilient to environmental stress and more and more vulnerable to extinction⁴; more genetic diversity equals more resilience through adaptation.

Then, species diversity “is the number of different species in a particular area and their relative abundance.⁵” This kind of diversity counts the number of different plants, animals, bugs and bacteria that live in an ecosystem. On this level, we look at the interdependence of plants and animals who each provide for different needs (like food, shelter, water purification, etc.). As each species has their own role within the ecosystem, the more species there are, the more able the ecosystem is to provide for all the needs of everyone in it.

Finally, zooming out even further, ecosystem diversity⁶ is the amount of different kinds of habitats in a given area, including: cold arctic tundras, forests, deserts, grasslands, and freshwater and salt-water habitats. These different kinds of ecosystems, or biomes⁷, are influenced by the weather, soil, and water in the region, all of which determine the different kinds of life (and communities of plants) that can be supported by the conditions. Each biome has its own unique way of supporting the wellbeing of the whole Earth’s ecosystem.

With all that in mind, while each kind of biodiversity is uniquely important, what they all have in common is this: diversity fosters resilience and stability. On every scale (genetic, species, and ecosystem), the more diversity there is, the more the whole is able to adapt to change and stress.

Here’s three ways in which biodiversity supports reliance and stability:

Firstly, it increases competition⁸. This competition supports resilience as it drives the development of niches⁹. With niches, species that rely on the same resources end up developing specializations which allow them to be extra-strong in unique circumstances. With these niches, they no longer need to compete to occupy the same place as others because they have created a speciality that no one else can compete with. The development of niches is what allows for many different species to coexist (and this variety is the foundation of biodiversity).

Overtime, these niches contribute to the overall strength of the whole through what’s called functional similarity (also referred to as functional redundancy¹⁰) in which multiple species serve the same function within an ecosystem (for example, many species provide food for pollinators; many mitigate erosion; many provide shelter; many purify water and air, etc). When it comes to ecosystem resilience, having more than one species on each job helps because if one is weakened, then there are others who can fulfill that function while the weakened one recovers. Think of this as the way in which thriving ecosystems keep a backup plan that makes sure that all the bases are always covered.

Then, from functional similarity, ecosystems develop response diversity¹¹ in which the different species that simultaneously serve the same function are able to do so at different times, or in the face of varying stressors. As different species are more resilient to different stressors¹², they each offer special support during the times that they’re especially strong (and conversely, each receives help under conditions that make them weak). This creates overall stability and resilience under life’s changing challenges.

Native & Invasive Species

Efforts to preserve biodiversity within the modern world often include the support of native species and the removal of invasive ones. In short, native species are plants that have been symbiotically co-evolving within an ecosystem for thousands of years¹³. Invasive species (or noxious weeds) are plants that dominate ecosystems and reduce biodiversity through their domination. These plants have been introduced from other places and end up outcompeting the balance that has been developed over thousands of years by native plants¹⁴. As they reduce biodiversity, they weaken the ecosystem as a whole, of which we are a part. 

To understand how this works, it’s helpful to remember that ecosystems evolve together in ways that allow for many different species to coexist. In the development of ecosystems over time, each species develops strategies to defend itself and maintain access to the resources that are needed for its survival. These strategies, which are called adaptations¹⁵,  vary depending on the needs of the species, and the environmental challenges that it faces in its biome¹⁶. A few of these adaptations¹⁷ include depth or width of root growth, water retention, adjustment to soil conditions (such as the ability to live in salty, sandy, dry, or super moist soil), and the development of protective skins, spines, barks, or chemicals. 

As all the species in an ecosystem develop their adaptations together, they naturally do so in balance with each other. For example, acorns developed tannins¹⁸ that are toxic to eat in order to protect their seeds. But, over time, deer have developed the ability to digest some tannins¹⁹; though it’s not good for them to have too much at once, the ability to eat them in moderation allows both the deer and the oak to benefit.

That being said, when a species is brought to an ecosystem that did not coevolve with it over time, the native plants of the new ecosystem may not have the strategies that keep the introduced species in balance with the whole. This lack of checks and balances can allow introduced species to dominate the ecosystem. When this happens, species are considered noxious weeds, or invasive. Though, over time, invasive species will come into balance with the rest, that process takes hundreds (if not thousands) of years²⁰. In the meantime, the ecosystem goes through an evolutionary crisis. 

Indeed, as noxious weeds reduce the population of native species, they have a tremendous impact on the interdependent balance of the whole. For example, if species who help purify water are harmed, then everything that depends on clean water is hurt by the pollution. If species who provide significant food for birds are harmed, then everything that depends on the birds is harmed. When one part of the ecosystem is hurt, it hurts everything that depends on it, which is everything -including us humans. 

That being said, birds and wind have always transported new plants to new places -and ultimately they’ve all found a way to work together. So, how is it any different now? Why’s it suddenly such a problem?

Though the answer to this question is complex, one of the reasons that it’s become so problematic now is because the introduction of seeds by humans (which is much faster than would happen with birds or wind) is compounded with the environmental conditions that have been created by modern development, which are particularly well-suited for noxious weeds²¹ and inhospitable for native plants. For example, the black mustard that has come to dominate the hillsides of California doesn’t depend on the fungi root (called mycorrhiza) in the soil that many native plants need to survive²². So, when human development disrupts the mycorrhiza through tilling, digging for construction, pollution from runoff, or from drying soil by water diversions, the native plants don’t tend to make it, but the mustard does. 

But isn’t this a good thing? Isn’t it better to have some plants growing rather than none at all? In some ways, yes. In other ways, no; when one species dominates the landscape, the ecosystem as a whole regresses to a state that’s less stable and supports less life. This is part of a process called ecological succession²³. In this natural process, landscapes cycle through phases of diversity, gradually growing from less to more diverse and thriving states; with the right weather and water conditions, barren landscapes eventually develop into grasslands which then become diverse forests and jungles that are brimming with life. Then, when natural disruptions hit (such as fires or volcanic eruptions), the diverse and lush landscape regresses to less complex, less stable and more barren states, thus starting the cycle over again. While this ecological succession is a natural part of life, as the rate of modern development has been so vast and fast, it has allowed for some species to spread like wildfire, quickly moving us towards these less complex, less stable and more barren ecosystems. 

So, to preserve ecosystems that support and stabilize large amounts of life (which we humans also need to survive), environmental stewards all over the world are taking steps to mitigate the spread of noxious weeds who would otherwise lead towards these kinds of ecological regressions. 

That being said, the process of mitigating noxious weeds is complex. No doubt, ideal mitigation is preventive; with less disruption and more restoration of native ecosystems²⁴, noxious weeds have less opportunity to take root; simply put, if we don’t provide conditions for their growth, they’re not as big of a problem. Also, we can prevent the spread of weed seeds by knowing which ones to avoid purposefully planting²⁵, and by being careful to remove the seeds that get stuck on us and carried around²⁶. Then, through early detection and rapid response²⁷ (meaning that weeds are found and dealt with quickly), it’s much easier to remove them by digging them out of the ground, simply because there’s less of them. 

But, early detection and rapid response is not always possible as it requires massive monitoring over huge amounts of land -and that’s not always feasible. Plus, some weeds have seeds or roots that can survive for a long time, making manual removal of them less successful as their seeds or roots may sustain, even if most of it is dug out. Some plants, even, have developed defenses where they grow even faster and more aggressively after they have been pulled or picked²⁸.

When noxious weeds are not easy to remove, sometimes “biocontrols” are available. Biocontrols are insects, diseases, or other animals that specifically affect the target weed and are intentionally introduced to an infected area²⁹. Ideally, biocontrols have been scientifically tested over long periods of time to assure that the biocontrol will only harm the intended weed (not other essential parts of the ecosystem). However, some folks are very weary of biological controls due to a history of harmful bio controls in the past (such as the mongoose that were introduced to Hawaii to address the rat-problem but ended up becoming a major threat to native birds³⁰). But, even when biocontrols are trusted, not all invasive species have trusted them available as an option.

For these reasons, environmental restoration groups often use herbicide to control weeds³¹, even as there is significant debate about herbicide safety (with some saying³² that herbicides may be as, or even more, harmful to the environment -and humans- as the weeds themselves).

All this to say, the preservation of biodiversity in the modern world is delicate and often humbling. For that reason, it’s important to work to get professional support when attempting to support native plants or remove invasive ones.

Keystone Species

In efforts to preserve the biodiversity of ecosystems, conservationists have identified species that play especially important roles in defining and maintaining the well-being of the whole. These species are called keystone species³³. While everything in an ecosystem plays an essential part in the whole, keystone species often meet multiple needs that others in the ecosystem do not; they have low functional redundancy. With that in mind, if keystone species are endangered, the whole ecosystem is greatly impacted by their absence. Here’s some of the different kinds of keystone species that are important to protect and support for the wellbeing of the whole³⁴:

Predators shape the whole ecosystem because the manage the population of the prey. If the prey population gets too big, they can diminish their own food supply and contribute to soil erosion, which can ultimately cause the loss of moisture. The loss of plants (from over eating), soil (from erosion), and moisture cause a domino of damage to everything that depends on them.

Conversely, there are some ecosystems where specific prey and/or plants are essential as they feed many different species in the ecosystem. Therefore, if they are over-hunted or somehow harmed, all the species that depend on them are also impacted.

Then, some species are considered ecosystem engineers. These are animals who impact the way that water or soil are distributed throughout the ecosystem. Beavers dams, for example, slow down the flow of streams and allow water seep into the surrounding area.

Similarity, habitat providers offer spaces for many other species to live.

Finally, pollinators are considered keystone species as all flowering plants depend on them for reproduction, and those plants are necessary for the many species that rely on them for food.

Conclusion

In sum, biodiversity builds resilience and stability through promoting specializations that ultimately work together to face the variety of challenges that life offers. That being said, the interdependence of ecosystems makes them paradoxically stronger and more vulnerable. This is because, no matter how strong we get as individuals in our niche, our wellness is always dependent on the wellness of those we depend on. On an ecological level, independence from the environment is impossible, and that makes us vulnerable to everything that we depend on.

With awareness of this, however, humans are amazingly equipped to devote our intelligence to stewarding conditions that nurture the wellbeing of the whole, of which we are a part. This, of course, includes supporting the biodiversity that fosters ecological resilience.

Listen to the song:

Stay tuned for more love from nature’s mirrors

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