This is one of a series of questions centered around living on a giant tree. The setting/scenario is described below:

In my fantasy world, elves live on a giant tree, very similar in structure to a Banyan Tree. The elves live on the branches of this tree, which average ~300 feet wide. The tree itself is wide rather than high, only extending 600-100 feet up. The branches are supported by massive aerial roots, as they are in older banyan trees. The elves can descend the trees to the massive fog-covered swamp below, but rarely do, meaning they have to live off of the tree entirely.

This question deals with the natural resources available to the elves, and what, if anything, they will need to survive in addition to what they already have.

Trade is established with the occupants of the massive fog-covered swamp below. Relations are strained however, and resources gained that way should be kept to a minimum.

Some details of the elves' situation are below:

  • Aside from the size, the tree is identical to a Banyan. Aside from providing wood, it also has all the medicinal uses of the Banyan. It also provides fruit. I am open to giving it additional health benefits if they are greatly needed.
  • Other plants and trees grow on the giant tree, so there should be no shortage of natural food.
  • Water collects on the giant tree in several small lakes, so water is available.
  • The giant tree is populated with creatures, so meat, skins, and bones are also available.
  • Aside from trade, the elves have no way to access metal or rock (unless they can somehow form on a giant tree, which I doubt).
  • The elves require weapons and armor.

What additional resources will my elves need to thrive? Or will they have everything they need?

  • $\begingroup$ So what's the question? $\endgroup$
    – Mormacil
    Apr 15 '17 at 21:20
  • $\begingroup$ You seem to have already listed everything your tree has. $\endgroup$
    – rclev
    Apr 15 '17 at 21:37
  • $\begingroup$ @Mormacil Hmm. Good point. :) I've edited the OP now. I also added another detail. $\endgroup$ Apr 15 '17 at 21:51
  • $\begingroup$ New question, what is the tech level of our elves and their neighbors? $\endgroup$
    – Mormacil
    Apr 15 '17 at 21:54
  • $\begingroup$ cooking will be hard, they need metal or stone to make non-flammable vessels and fire pits. Bone will work for many tools but not all, and it will be inferior in most cases. They will also have to spend more time foraging since they will not have high yield grain crops. $\endgroup$
    – John
    Apr 15 '17 at 23:15

Given that I have no idea how hard of science you're looking for in this answer, I'm going to assume hardish and move on from that assumption. Two problems which I will address in turn.

which average ~300 feet wide. The branches are supported by massive aerial roots, as they are in older banyan trees

Impossible, so we're going to pretend it's a magic tree that can get enough photosynthesizing energy, water, and nutrients. In order to support its own weight, it'll have to be extremely light or extremely hard wood. Given that it wasn't blown over, somehow it's going to have to be both. Aside from all of the tallest trees being hardwood, it'll make some of your elf's other problems easier. You are still left, however, with a rather serious problem.

Weather. On a normal day, your elves can expect 160km/hr wind speed (100 mph). Storms would simply kill them outright. This means your elves are going to be spending most of their time inside the tree, which will sway and bend under the force of the winds regularly -- much like modern skyscrapers. You're going to have to be careful to only inhabit the largest branches and not to kill them via the tunneling for your home.

Aside from trade, the elves have no way to access metal or rock (unless they can somehow form on a giant tree, which I doubt). The elves require weapons and armor.

I'd look at how the ancient Quechua people (the Incas) conducted warfare against the Spaniards, I can suggest a couple of books if you're interested. They did not have access to metals suitable for warfare, while the Spaniards had horses and steel. Aside from that, however, I'm going to suggest you use the wood itself. In order to stand up the conditions that it has to the wood is going to make carbon fibre look like a primitive joke, it's going to be lighter and harder than anything we've (RL humans) have come across before. Due to wind speed, there is 0 point in projectile weaponry until you have ballistics it's pointless. Instead, you'll be getting very deadly wooden edged weapons.

On an unrelated note to the exact question, I'm going to suggest you call the magic tree a gum tree. They're the second tallest type of tree as far as I know, so that works out pretty well. The main reason, though, is that the bark is thin and soft making good clothing. Additionally, the sap can be used as an adhesive and, while not tasty, a food source.

I wrote this quickly so if I'm not clear about something shoot a comment and I'll get back to you. Cheers!

  • $\begingroup$ I was sure I included it in the question, but I guess I missed it: the tree is only 600 feet high, 1000 at most. High winds shouldn't be a problem (I'm no weather expert though, so maybe that's not the case). I'm not aiming for a high tree here, that creates all kinds of problems. Also, the tree is pulling water from the large pools it forms on its branches. This helps with the water transport problem. $\endgroup$ Apr 16 '17 at 0:16
  • $\begingroup$ @ThomasMyron I can't be certain, but 600ft is around 55 stories so I would assume the quick and dirty measure of 100mph would hold roughly true. It's all highly dependent on wind patterns, local geography, high above sea level, etc. But, if you're at that height and there aren't other things blocking/slowing down the wind around you then you can expect very high wind speed. $\endgroup$ Apr 16 '17 at 4:00
  • $\begingroup$ What about the tree itself? Wouldn't that slow down wind speed? It is very massive, after all. It is also growing from a large swamp, which can easily be a bit below sea level, so the whole thing isn't too high as far as altitude goes. What sort of geography could I use to slow down the wind? $\endgroup$ Apr 16 '17 at 4:58
  • $\begingroup$ Large mountain range surrounding the tree. However that wouldn't go well with the swamp/humidity that requires. $\endgroup$
    – Mormacil
    Apr 16 '17 at 15:22
  • $\begingroup$ @ThomasMyron the basic issue here is that wind experiences friction as it passes over the ground which slows it down. If there was nothing to slow it down over a large course of time it really picks up. If you were sufficiently below sea level though you'd have to deal with far lower wind speeds -- especially if it were a sudden drop. I'm not too familiar with the geography of swamps, but I'd assume it'd have to be fairly flat so that the water doesn't drain. In which case you run into the problem of how to make the drop in elevation sudden. $\endgroup$ Apr 17 '17 at 15:59

Height is a huge problem here. You might want to go wider instead of taller, because 50 stories up (that's what 600 feet is) conditions change considerably. You need sun to grow things, but at that height, the wind would be so bad that you couldn't do much as far as growing things is concerned. You'd have to place the garden more towards the center of the tree, with nothing blocking the sun. I know that in movies there's always a rooftop garden atop the tall building, but...it does not work at 50 stories.

20 stories up is pretty darn tall, as is 10 stories--so maybe most people don't LIVE in the tallest reaches, unless they are in the center.

The good news is this: you have a power source. We aren't talking high science here. We're talking windmill power. So high up in the trees you might have wind turbines. These could be used to run simple mechanisms or grind seeds (on the ground it would be used for something like wheat). Mills, powered by wind or water have been around since the Greeks, and were in extensive use in Medieval times. They could be used to extract oils from seeds and any number of applications which could help them to process their food resources and make better use of everything they have. This is old, old tech. It can also be used to compress bark and or leather for armor making.

As to the animals inhabiting the trees, and the process of tanning hides, yes a mill can help!! There's something called a bark mill that you should look into.

When looking at water supply, I found myself stumped because we don't know how big your "lakes" are or how many people need to be supplied. You want to handwave the water problem away, you can, but water is heavy, and your tree is already...well, it's big, and a normal banyan would have collapsed under the weight of itself, let alone what was built on it, plus lakes...definitely want to have magic involved, even if it isn't obvious.

I hope they have another source of water other than what falls from the sky--I'd look into the Mayan system of managing rainwater, and apply it to trees.

Do keep in mind that if they are collecting all this water, it isn't falling to the ground, and the tree might need it. (Or it could be in a swampy place and doesn't--just keep it in mind).

Other plants and trees grow on the giant tree, so there should be no shortage of natural food.

The above is going to depend on your population numbers. You've given us size of environment, now we have to figure out how much flora and fauna can live in that space, and at what height, and how many people that would actually support.

I don't know what you expect our answer to be since you list that they have all the water, and food they need. Everything else, like medicine, armor, furnishings and clothes, can probably come from the other stuff they already have.

The thing I would ask, whenever building any civilization, is where does the poop go?


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