What is a keystone species?

Three years ago, That Blog wrote about functions – useful things that plants and animals do. Normally, in nature, each type of plant and animal performs many functions, and each function is performed by multiple plants and animals. This is why we see complex, thriving ecosystems, in which all the members are involved in a web of interactions.

But within an ecosystem, some members are especially important. Often, this extra importance comes from the fact that the plant or animal performs a function that isn’t duplicated by another plant or animal in the system. These critically necessary members of ecosystems are called keystone species.

Keystone species can be important for many reasons. Maybe a certain kind of small animal is the only prey of a larger animal. If the small animal disappears, the larger animal will too, because it has nothing to eat. Because the fate of the larger animal depends entirely on the fortunes of the smaller animal, the smaller animal would be considered a keystone species.

Conversely, if a large animal was the only predator of a smaller animal, then the large animal would be the keystone species, since without it, the smaller animal would multiply prolifically, decimate its own food sources, and unbalance the entire ecosystem.

As another example, an insect could be a keystone species, if it is the only animal that pollinates a certain plant. The disappearance of that insect would then spell trouble for the plant, as well as for every species that relies on the plant.

The name keystone – a reference to the single wedge that holds an entire arch together – might make it sound as though each ecosystem has only one centrally important species. But this is not the case. An ecosystem can have many crucial members. In fact, the more scientists learn about ecosystems, the more they think that every species can be described as a keystone species.

Plants and animals do all kinds of things – for each other, and for us – and we still don’t know how all of these interconnections work. Rather than treating uninteresting species as disposable, we should take the more cautious approach of assuming that every kind of plant and animal is important. We just don’t know which species, once it’s gone, will turn out to have been holding the whole system together.

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What is a keystone species?

What is anthropocentrism?

When someone thinks their own needs and opinions are more important than everybody else’s, we call that egocentrism (or self-centeredness). We generally don’t find it very flattering to be described that way.

Anthropocentrism is the idea that the needs and opinions of humans are always more important than the needs and opinions of other species. Put another way, it’s the idea that plants and animals are really just here for human use, and that their basic survival requirements can be ignored in favor of satisfying any small desire that a human might have.

When we end the lives of trees so we can print and mail more department store catalogs, that’s anthropocentrism.

When we destroy wildlife habitat to build another golf course, that’s anthropocentrism.

When we think that the most important thing about our yards is how they look to human eyes, that’s anthropocentrism.

The opposite of anthropocentrism is biocentrism. Biocentrism does not mean believing that plants and animals are always more important than humans. It does not mean that humans are bad and should be eliminated from this planet. Rather, it’s the idea that the needs of humans and of other species can be balanced against each other in a way that honors all forms of life.

Biocentrism makes sense for two reasons. First, the needs of humans and of other species are often not at odds with each other: we all need clean air and clean water. Humans do better when nature is thriving, and when we destroy nature to make more room for people, we cause a lot of harm to ourselves as well.

Second, respecting the needs of other species is simply the right thing to do. Many people today think that something is wrong when CEOs pay their employees starvation wages in order to further increase their own salary so they can buy a baseball team, a yacht, or a fourth house. Similarly, it is wrong to deny the basic needs of other beings so that we can have more stuff that we don’t even really want.

When we simplify our lives, our world has enough for everyone – ourselves, other humans, and all the species we share this miraculous Earth with.

What is anthropocentrism?

What is zero waste?

The average American throws away four and a half pounds of garbage every day. We put that garbage at the curb to be taken “away”, to landfills that are rapidly overflowing. Garbage litters our cities, rolls around our national parks, and floats in the ocean, forming huge gyres that are set to outweigh all the remaining fish in the not-so-distant future.

Garbage is a problem.

To address this problem, some people have adopted a lifestyle known as zero waste. While practitioners typically don’t achieve a total elimination of garbage from their lives, some have famously produced only a single mason jar worth of trash over the course of several years.

There are some obvious ways that we can all reduce our garbage. We can give up single-use items such as plastic silverware, disposable straws, and styrofoam cups. We can stop buying things that come wrapped in excessive packaging. We can wear clothes until they are threadbare rather than merely out of fashion. We can borrow items from friends instead of buying our own. We can take care to divert our waste to our compost pile or our recycling bin, rather than sending things to the dump.

But where should we start? One way to answer this question is by conducting a garbage audit.

Strictly speaking, a garbage audit is a scientific study that involves laying out the entire contents of your trash can, and weighing and categorizing everything you find. For most of us, though, a more informal “garbage survey” is enough to answer the question: What am I throwing away a lot of? Once we have that piece of information, we can think up ways to dispose of less of that thing.

We may find that we produce a lot of food waste, or that we throw out lots of everyday items that could be replaced with reusable alternatives. Or, we may notice that we drag a lot of grass clippings and raked-up leaves to the street. The solution to that type of waste is simple: Leave the leaves where they fall, to insulate plants over the winter, add nutrients to the soil, provide places for pollinators to hibernate, and suppress the germination of weeds in the spring. And let the grass grow, to absorb carbon, provide structural support for flowering plants, and ripple beautifully in summer breezes.

When we begin to recognize yard “waste” as valuable resources, it’s easy to reduce our trash.

What is zero waste?

What are co-benefits?

co-benefits

What if climate change turns out to be a hoax, and in our efforts to prevent dangerous global warming we instead end deforestation, create good jobs, and reduce air pollution for no reason? That is the question posed by the audience member in this cartoon. Clearly, this person does not understand the value of co-benefits.

Co-benefits are the additional positive outcomes created when we address some problem. For example, if we decide to eat out less often because restaurants are expensive, the primary benefit is that we save money. The co-benefits might be that we eat healthier food and discover a passion for cooking.

There are plenty of co-benefits when it comes to sustainable gardening. Whatever our reason is for shrinking our lawns and putting more native plants in our yards, we enjoy all kinds of positive outcomes in addition to the one we were aiming for.

If we plant natives because we don’t want to contribute to the climate crisis by running a lawnmower, we also enjoy cleaner air in our neighborhoods.

If we install water-wise landscaping to help conserve limited water supplies, we also save money on our utility bills.

If we stop blowing leaves into the street because we want to use that organic material to build soil, we also experience more peace and quiet in our community.

If we stop spraying pesticides because we don’t want to expose ourselves and our neighbors to carcinogens, we also gain the opportunity to observe more life in our yards.

 

We all have different reasons for choosing to switch to more sustainable gardening practices. But whatever our entry point, we can hardly help bringing about a whole host of additional advantages for ourselves and others. That is the power of co-benefits.

What are co-benefits?