Solving the vulnerabilities of a plant-based life-form's civilization: sunlight, roots, and hibernation

Question

Say you are a plant-based life-form (imagine a walking tree). You have roots and leaves.

You have two main vulnerabilities:

1. You need sunlight on your leaves for photosynthesis to get energy.
2. You need to root yourself in the earth occasionally to absorb water and nutrients.

And you also face a serious challenge if, like your non-sentient cousins, you lose your leaves for the winter and must enter a period of extended hibernation.

Additionally, your offspring are numerous, extremely frail and take a long time to mature.

How can such a race build a successful civilization? Especially if challenged by other civilizations.

Clarification Update:

By "Civilization" I mean a society with towns, cities, governments, politics, armies, etc. These are not all required, but just to emphasize what I mean by Civilization. Not just a loose collection of beings, but a whole nation as it were.

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Some of the main issues I see:

1. The race must always have access to nutrient rich earth and sunlight.
2. The entire race might be hibernating at the same time.
3. Dependent on seasons.

Answer 1

TLDR; The same way any tree does!

The key to any plant based life form is numbers. You'll need to decide what you want your species' main "predator" to be.

Is it herbivores that like to feed on your offspring (seeds)? Depending on the herbivore, they have their own predators to worry about, and won't be able to eat ALL of your offspring before retreating to their own home. Are they a predatory animal that uses your race for habitat but preys on animals that feed on your offspring? Chances are your offspring are safe from these, as the population of this animal can grow as yours does. The mutual benefit of not only protecting your species, but making sure that your species grows is a boon to both parties, as yours is the reason their food gravitates to them.

Regardless of what you choose, being a tree, young saplings are less likely to be feasted on by the other kingdom.

The next step for your species is to create a symbiotic relationship with fungus, as the decomposition of your species' corpses will renew the nutrients and provide more fertile soil.

On the other end of the spectrum, plants and fungi engage in mutually beneficial relationships, the most important of which is called mycorriza (plural = mycorrhizae) where fungi live on and in the plant’s roots. In this case both the plant and the fungus depend on this relationship to develop and survive.

So you've now solved predators, and soil/nutrients. Seasons are the last problem for you to solve, but it is admittedly the easiest. Hibernation is something that not only plants, but animals do as well. Those that don't are either predators, feasting on small animals, or don't leave their burrows for anything but leftover food (essentially the offspring of yours that didn't make it). When winter comes, the majority of animals either save their energy for other pursuits (growing fur for hunting, and saving lipids), hibernate (or frequently take naps), or migrate to warmer climates.

Your species during these winter months will do what all trees do! Stop producing offspring, shed leaves, and go into dormancy. Sunlight in this state is not really necessary, and your species will have the "instincts" to do this as a group, similar to animals. For more information about how the tree knows when to lose it's leaves,

Dormancy is like hibernation in that everything within the plant slows down. Metabolism, energy consumption, growth and so on. The first part of dormancy is when trees lose their leaves. They don't make food in the winter, so they have no use for masses of leaves that would require energy to maintain. When it's time for trees to lose their leaves, a chemical called ABA (Abscisic acid) is produced in terminal buds (the part at the tip of the stem that connects to the leaf). The terminal bud is where the leaf breaks off when it falls, so when ABA gathers there, it signals the leaf to break off. (This occurs only in deciduous trees — not in coniferous trees.)

In the end, unless you're a coniferous tree, you have nothing to worry about but living a long successful life (until humanoids.....).

If you're species is coniferous, the greater number of "leaves", and the reduction in the water they need is key. As a conifer, you also have a special substance called cutin, which when combined with the lesser amount of water, will prevent the leaves from freezing.

These are very small and thin needles that can be thought of as a leaf tightly coiled together. They cover themselves in a waxy substance called cutin. These needles also require less water to stay alive and perform photosynthesis than leaf. The small amount of water and protective Cutin coating stop any water from freezing and killing any pine needles.

In the end of it all, no matter what tree you are, you'll have a larger problem uprooting yourself than survival, and will move infrequently as a result of photosynthetic energy being less than that of other methods.

If you compete with other trees, it'll just be a numbers game. If you produce more offspring or have a more aggressive root system, then your tree will take over new territory than your possibly non sentient neighbors.

Using computer software to predict the growth patterns in forests over time, Dr. Dybzinski and his colleagues are now reporting that the overabundant roots act as weapons to prevent other trees from growing.

Answer 2

The trick of having tree civilization is why? A tree does not need other trees, it may appreciate predator warnings from its neighbors, and may co-operate in root based defenses or support for inter-plant-species competition, but more or less each is an island onto itself.

But let them band together against the ax wielders or something. Do what humans do. In the early days we used guard dogs, let the tree-people do the same. Breed big mean predators to scare off herbivores and ax wielders. Build walls to keep interlopers out of the places you sleep. Make alliances and crush your enemies before they hurt you.

Cities might work differently, for humans a city requires large hinterlands of farming to support it, but for trees that is the meaning of a house. A pond and mud patch surrounded by high walls where you can dig in and feel safe. Multistory dwellings would be kinda unlikely since sunlight is the main resource. Roofs won't be a thing.

Think about how many trees a typical tree spawns, thousands of seeds for a few sprouts for a couple mature trees. This could be vastly improved upon; human raised trees are nearly one seed to one tree which could mean you will have huge population growth. If you care for your kids. If not you could let the seed scatter and welcome back any juveniles that prove smart and strong enough to find their own way home.

Answer 3

Building on @NotStoreBoughtDirt's answer, perhaps it would be helpful to explore what a civilisation of sentient mobile tree-people might look like.

At the dawn of their civilisation, say early tribal organisations and limited technology, the most important innovations would likely be things like walls and domesticated predators to fend off herbivores. These would be especially important during the winter where even if they were still active they'd have a lot less energy to spare.

As their civilisation develops into something akin to classical antiquity, the importance of walls and predators would still be present. If there is conflict between tribes of tree-people then it would probably follow a similar pattern to human conflicts of the time, with a campaigning season during the summer and an off-season during the winter. You'd have to find a suitable resource for them to fight over though. Dirt and sunlight aren't exactly limited resources.

You might expect a boom of civilisation in equatorial latitudes where tree-people could operate year-round. Either tropics or equatorial river deltas like the Nile. Perhaps that's the resource they're fighting over. If you have temperate tree-people they may try to push into more tropical latitudes. If you have evergreen tree-people then they may pose a significant threat to temperate tree-people by being better able to campaign during the winter. Another option for a resource to drive conflict or trade is high quality soil, or water in arid climates.

I'd expect cities and settlements to be one-level and sprawling, and likely difficult to defend because of that fact. The invention of the mirror may be a significant development in city construction, allowing direction of sunlight within structures, allowing for better fortification and more compact and defensible settlements. The aquaduct and draught animals for transportation of water and soil would also be important innovations (speaking of soil, perhaps they sleep in soil to absorb nutrients seeing as they'd likely be dormant then anyway).

Electricity would probably be the breakout invention of your tree-people's civilisation, enabling all tree-people to be active year-round regardless of latitude, active throughout the night, and allowing our tree-people to explore hitherto unreachable destinations on their world. It would also allow far greater urban development and population density than ever possible before.