Have you ever wondered if plants need help from humans in order to survive?
We know that plants don’t depend on us for food, but do they depend on us for other things, or would they manage just fine if all the humans (and animals) disappeared from the world tomorrow?
So, can plants survive without humans or animals?
Surprisingly, some species of plants would struggle without humans, and many plants would be wiped out if animals were not around either. If plants were the only life left on Earth, it’s unlikely that some of the popular species we know today would survive, but most plants would continue to exist and thrive, even without humans or animals.
There is a variety of reasons why plants can survive without humans or animals:
Table of Contents
Do Plants Need Humans To Survive?
Plants don’t directly need humans to survive.
Let’s explore the things that plants must have to survive, and then consider this in terms of their relationship to people.
These are the 5 things that most plants need to survive:
- Pollination/seed distribution
So, do they depend on human input to get any of these?
Individual plants species may do, such as hybrid vegetables or certain crops, but as a whole, the plant kingdom does not need humans for any of these.
Plants get their energy from the sun, photosynthesizing its light to produce most of their food. The remainder of what they need comes from the soil in which they grow, and they take this up through their roots.
If a plant does not have access to natural light, that’s when humans can help the plant survive by providing artificial light. Surprisingly, it works just as well as natural light. Here’s more about this topic.
So, unless a plant is deprived of sunlight, we are not required for the provision of food or light.
A plant gets both of these things from the sun.
They don’t need us for water either; they collect rainwater in the same way, sucking it up from the soil with their roots.
Unless a plant is in a pot in your home, it doesn’t need you to bring it water.
So, what about CO2? Would plants die if we stopped producing CO2 for them to “breathe?” Again, probably not.
Although we do produce CO2 for them, animals serve this purpose just as well as we do, and the drop in CO2 levels would probably be fairly insignificant, even if all humans were wiped out at once.
In fact, plants get most of their CO2 from microorganisms, and they even produce it themselves. It’s unlikely that human extinction would make much difference to the CO2 levels.
So, what about warmth?
Again, plants don’t need us to provide warmth, and indeed our contributions to global warming are causing more harm than good in terms of maintaining the temperature that plants need.
We aren’t helping them there! They get the warmth they need from the sun.
The final thing that plants need in order to continue their species is reproduction. This has two parts: pollination and the spreading of seeds.
This is where some individual species do rely on humans to a degree, although it’s arguable how much – they might easily evolve to work with some other pollinator, even if we are currently the main one.
Most plants also rely much more heavily on animals, birds, and insects for this process, and most plants would do just fine without the input of people to pollinate them or spread the seeds.
While we certainly affect which plants tend to reproduce and get spread around the world, the plant kingdom does not depend on us for this process as a whole.
It seems plants would manage pretty well without a human population to keep them going.
However, this rule does not apply the other way around. Check out this article where I explain why plants are so important for us, humans.
Certainly, if humans disappeared at some point, things would change, but plants would be unlikely to stop existing just because we did. There are many other creatures that could fulfill the roles we play.
Why Do Plants Need Humans? (Do They Depend On Us At All?)
Surprisingly, some plants do need humans to a certain degree. Let’s explore some examples.
Plants that struggle to propagate themselves are probably at the top of this list.
If you take one of our more modern cultivars, it’s much more likely to be dependent on humans for its survival, partly because we have molded it to suit our needs, rather than fitting in with the natural world.
Some plants would be very likely to die out if we stopped existing. However, most of these would not naturally exist anyway – and so their dependence on us is directly fueled by our interventions.
It is true that our efforts can be beneficial to the plant kingdom and to nature in general.
For example, fields and woodlands benefit from our input to some extent. We can help to maintain these spaces by removing dead wood, making room for new growth, re-seeding areas that have suffered from damage, etc.
We also provide fertilizer and, at least in theory, help the ecosystem to balance itself, ensuring no plants get out of hand and take over.
However, it’s important to note that while we may do these things in theory, plants will manage reasonably well even without our input, and often this input is damaging, even when we have the best intentions.
The bottom line is that some individual, delicate species may depend on humans for their survival, but the plant kingdom as a whole most probably does not depend on us.
If our species were to go extinct, plants would continue to exist, especially if they still had animals to help with the problems they experience.
We would likely see a very different world as a result, because agricultural land would become wild again, but the plants would go on in some form or another.
Do Plants Need Animals To Survive?
The short answer is probably no, plants don’t absolutely depend on animals for their survival.
However, this is much harder to say for sure.
That’s because a far greater number of plants do depend on animals to spread their seeds and also to fertilize them.
Many plants have adapted to depend on specific animals to keep themselves alive, and without these animals, they would probably cease to exist. However, a lot of species are not so invested in single relationships, and would likely find other alternatives to meet their needs.
Let’s look at the needs of a plant in relation to animals – how do animals help keep plants going?
Plants don’t need animals to provide them with food or sunlight directly.
However, the fertilization of animal feces and animal bodies when they die doubtless keeps the soil richer and gives plants food.
If there were no animals in the world, it’s possible that the soil would not be so rich, and some plant species might disappear.
Plants don’t need animals for water or for warmth, but the problem of CO2 might become much bigger if animals were to die out completely.
It’s difficult to weigh this up, but plants could probably still survive based on what microorganisms produce, and what they themselves output.
Removing animals might disturb the balance, but it would be unlikely to completely destroy it. Equally, if fungi continued to exist, these would provide the plants with CO2.
The pollination and seed dispersal is probably the area where plants would suffer most significantly.
Many plants need animals or insects to pollinate them or spread their seeds around and carry them to new environments.
An argument against plants needing animals for this is that plants are thought to pre-date animals by several million years. However, many modern plants have evolved away from their ancestors’ reproduction techniques, and might not survive if animals couldn’t help to pollinate their flowers and spread their seeds.
Overall, it seems likely that plant life might continue in some form, but it would likely be very different from the flora that we recognize today. Many of the species that exist now would disappear.
Why Do Plants Need Animals To Survive?
Plants need animals mostly for pollination and distributing their seeds.
Of course, not all plants depend on animals for this, but most have at least some interaction with them at some point. Otherwise, they have to depend on the wind to spread pollen and seeds.
A lot of plants would go extinct without animals.
For example, the Great Indian Rhinoceros disperses the seeds of the Trewia tree in the grasslands where they will grow. If these seeds stay in the forests where the adult trees drop them, they do not sprout, as they won’t grow in shade.
That means that if the Great Indian Rhinoceros ceased to exist, the Trewia tree would quickly die out too.
While this is just one example, it’s clear that many plants would not survive without the input of animals. The plant kingdom as a whole might continue, but it would need to change dramatically in order to do so.
Plants do not seem to directly depend on humans or animals for much, but the types of plants and the way in which they interact with the world (particularly for pollination and seed dispersal) would likely need to alter quite radically in order for plants to continue.
Removing humans would probably cause a minimal upset in the balance, but it certainly would see dramatic changes because we have such an impact on our environment.
Removing animals would likely cause a lot of change as some plant species died out, and others altered their behavior.
On the whole, however, it seems likely that the plant kingdom would continue in some form.