Fantasy Races and Population

[Spellbreaker26]

A discussion started on another thread led me to start one here.

A] How do Dwarves in mountain kingdoms eat? More importantly, how do they make alcohol? Same goes for every underdark race.

B] Does living in a forest put a hard limit on the local wood elf population? Can it support as many people as human cities drawing food from farmland can?

C] If elves are immortal and never age beyond the point where they can reproduce, why haven't they overtaken the planet?

These are the sorts of questions I ask myself when I am designing a setting. How do you guys think?

[eru001]

How I've handled it in my campaigns

A] There are a number of means by which the dwarves acquire food.

The first is by subterranian agrigulture. Utilizing a variety of techniques the dwarves cultivate and harvest a large number and variety of edible mushrooms and other fungi which grow well in a subterranian environment so long as these crops are provided with good fertilizer, (Dwarf excrement works excelently for this). Some dwarven cities, built into mountains containing lava flows have also managed to breed strains of wheat and oats which grow well in caves adjacent to said flows. Powerful dwarven Rune lanterns set into the ceiling of caves and tunnel vaults are also noted as capable of providing enough light for surface crops to grow, with the added benefit of not needing to worry about inclement weather.

The second is via herding and hunting. Mountain goats are a popular and well known livestock among dwarves. Though dwarves are also known to raise stocks of other cave dwelling and subterranian animals. Dwarves are also expert ambush hunters, utilizing a number of styles of trap to ensnare large cave dwelling mammals such as wolves and bears which attempt to use either natural caves which the dwarves have tunneled into, or dwarf-made caves built specially for the purpose of hunting such animals

The third is through cave-fisheries. There are a number of species of fish which can survive well in cave pools, provided a source of food is supplied by somone tending the pool. Dwarves raise large quantities of these fish, feeding them on mushrooms and other such fodder. The most popular by far is called the "Blindfish" which eats primarily fungi and insects. It is praised by many as one of the more delicious freshwater fish and is exported as a delicacy by many dwarf holds.

The fourth of course is trade. Dwarven kingdoms are well known throughout the world for their expert craftsmanship and wealth in terms of mineral ore. If they find themselves in a shortage of food it is simply a matter of contacting one of the human kingdoms on the surface with a surplush and arranging a trade. Dwarven merchandise is prized throughout the world and human merchants are more than willing to pay for it with grain and other agricultural products, which many human nations have in abundance.

B]

Yes it does. Unimproved forrest can support a much lower population density than cleared and properly maintained farmland.

C]

Several reasons.

1. They take a long time to reach maturity and have a much longer gestation period than humans. It simply takes them much longer to reproduce.

2. While immune to the passage of time, they are still vulnerable to all of the other horrible ways in which things can die. they usually have 6 centuries or so before falling foul of a tragic (or not if you are a dwarf) accident

3. Dwarves do not like elves. Dwarves are violent. Dwarves are industrialized. Dwarves drink heavily. Dwarves are thus highly effective at keeping the elf population under control.

4. Humans are like dwarves, if you swap out the industrialization for sheer numbers, and a lack of concern for one's well being combined with inventive deviousness, and devious inventiveness.

5. Elves have a tendency towards pacifisim or at least towards, non-expansionism. They already live in the nice parts of the world. what do they want with trying to take over the not so nice to live in parts. Where is the benefit?

[SilverLeaf167]

A] There's actually a lower class of dwarves that lives on the surface, near the entrance to the mountain-home or whatever you'd call it, and farms food much like human peasants would. There are also some underground crops and livestock, and mushrooms in particular are used for food and liquor alike. Having to rely entirely on these subterranean alternatives is one reason that completely Underdark populations don't usually grow very large.

B] Wood elves do indeed have relatively small communities and scattered tribes, as opposed to high elves who live in more advanced cities and practice agriculture.

C] Well, in D&D elves aren't actually immortal to begin with, and have a hard cap of 750 years (average death by old age is at 550) though I've further toned that way down to around 350, and the general populace doesn't necessarily reach even that. They tend to have relatively few children for both cultural and physical reasons and little interest in expanding from their home continent.

All are important questions that I too have encountered at some point and simply thought up answers to.

[JAL_1138]

A discussion started on another thread led me to start one here.

A] How do Dwarves in mountain kingdoms eat? More importantly, how do they make alcohol? Same goes for every underdark race.

B] Does living in a forest put a hard limit on the local wood elf population? Can it support as many people as human cities drawing food from farmland can?

C] If elves are immortal and never age beyond the point where they can reproduce, why haven't they overtaken the planet?

These are the sorts of questions I ask myself when I am designing a setting. How do you guys think?

Dwarfs live on rats (with ketchup), aside from the (in)famous dwarf bread, which often contains gravel and is not so much baked as it is forged.

Alternatively, dorfs farm for underground plants such as plump helmets, pig tail, cave wheat, and sweet pods, which can be brewed for alcohol or used for cooking. They obtain meat from excess dogs, mole dogs, elephants, and other animals. Suicidal dorfs ocassionally attempt to fish in underground streams, usually dying horribly. Wood(-like) products come from such subterranean plants/fungi as tower-cap.

[VoxRationis]

A discussion started on another thread led me to start one here.

A] How do Dwarves in mountain kingdoms eat? More importantly, how do they make alcohol? Same goes for every underdark race.

B] Does living in a forest put a hard limit on the local wood elf population? Can it support as many people as human cities drawing food from farmland can?

C] If elves are immortal and never age beyond the point where they can reproduce, why haven't they overtaken the planet?

A) Chemosynthetic organisms provide food around geothermal wells, which require careful management and tending, thus leading to heavily centralized city-states surrounded by deserted territory with little to no population. Alternatively, surface-adjacent dwarves might have terrace farming or large greenhouses. Certain underground groups might get much of their energy from raiding or hunting above ground.
I've had a number of setting where dwarves don't actually make a lot of alcohol, but simply consume it in human lands because they digest it better than they do starch.

B) Absolutely not, assuming it's a natural forest. If it's actually some sort of cultivated silviculture full of domesticated fruit and nut trees, it might have a comparable carrying capacity to farmland. Otherwise, you need something like 100 times the foraging ground to support a single person as a farm would support.

C) In many settings, elves are long-lived rather than immortal. In others, frequent war might make a difference. In one of my settings, numerous elven cultures had artificial violent conflict as a form of population control. Other elves might just not breed very commonly. After all, how often are pregnant elves, or elven children, depicted?

[Beleriphon]

B) Absolutely not, assuming it's a natural forest. If it's actually some sort of cultivated silviculture full of domesticated fruit and nut trees, it might have a comparable carrying capacity to farmland. Otherwise, you need something like 100 times the foraging ground to support a single person as a farm would support.

Do note that this is possible. The native people of North America did to this great success, to the point that a well tended region could easily support thousands of people. In effect the "forest" wasn't a forest at all, it was a massive garden that the people tended, nurtured and intentionally grew and managed, often using fire to clear underbrush and other unwanted plants.

[veti]

C] If elves are immortal and never age beyond the point where they can reproduce, why haven't they overtaken the planet?

A better question would be, "why haven't they completely died out?" Slow breeding is an absolutely crippling evolutionary disadvantage, unless you have some pretty foolproof ways of avoiding predation or other violent death, which elves (in most settings) don't.

That's why certain settings (Middle Earth, basically) paint elves as a race in long-term decline, fighting a rearguard action against being completely supplanted by humans.

[Spellbreaker26]

These are some great answers guys.

Now I've got plans for some Aztec-type wood elves - should also deal with the problem of wood elves always being too passive, in my eyes. Always preferred the wild side to the hippie stuff.

Liking the dwarf fungi thing. Also the "trading with above ground factions" is what my mind initially went to, but that leaves you cripplingly dependent on outsiders and neuters the main advantage of living in a mountain (protection for a siege).

[Mechalich]

A] How do Dwarves in mountain kingdoms eat? More importantly, how do they make alcohol? Same goes for every underdark race.

Well, in the case of dwarves, traditionally they raised most of their food above ground in alpine areas like other typical medieval cultures (a good analog would be the Swiss), they just built their cities into the mountains with large areas extending underground.

Still, with regard to underdark dwelling populations, you do run into the problem of not having photosynthesis as an energy source. You basically have two options in order to have a vibrant underdark populace without massive handwaving. The first is to massively crank up the functional production of chemosynthesis and its frequency to allow for a whole chemosynthetic ecosystem that both matches photosynthetic production and isn't critically location limited in the way major chemosynthetic ecosystems in places like the deep ocean actually are. The Faerunian explanation - that the underdark is infused with this weird form of energy specific to the underground - is actually a good one in this regard. The second explanation is to go for full on magical production of food.

B] Does living in a forest put a hard limit on the local wood elf population? Can it support as many people as human cities drawing food from farmland can?

It's not the 'living in the forest' part that matters here its the 'not having agriculture' part. If the wood elves are living as hunter-gatherer tribal people (like the Kagonesti from Dragonlance), then yes, that imposes limits on their population density because that lifestyle cannot produce the same amount of calories per hectare or even close to it and therefore the carrying capacity is much lower. That being said, in a fantasy world there's no reason why elves can't develop some form of 'forest agriculture' that allows for high productivity within the forest environment without having to get rid of the forest. For example, perhaps the elves breed tree cultivars that are hyper-productive and over-produce massive quantities of sugary sap and they tap this and live like giant mammalian treehoppers.

C] If elves are immortal and never age beyond the point where they can reproduce, why haven't they overtaken the planet?

As has been mentioned, traditional D&D elves are not immortal and actually have a naturally lower birth rate (and a prolonged pregnancy) compared to humans, which limits their population size. Additionally, in many D&D settings elves are something like Old Growth obligates - they only live in primary forest habitats. If you cut down a forest and convert it into farmland, elves never both to recolonize the region even if the forests are restored.

Even if the elves are immortal - in terms of lifespan - that doesn't necessarily translate into power. In D&D comparative power between nations, races, and civilizations is determined entirely by who can cast the most power spells the most often. One epic-level wizard is worth infinity level 5 fighters. Being immortal and not having the biggest magical stick just lines you up for an eternity of suffering. People who have immortality are more likely to have the time to develop phenomenal cosmic power, but it's not a dependent capability (heck, if D&D is to be believed, it's easier to turn phenomenal magical power into immortality than the reverse).

[MarkVIIIMarc]

A better question would be, "why haven't they completely died out?" Slow breeding is an absolutely crippling evolutionary disadvantage, unless you have some pretty foolproof ways of avoiding predation or other violent death, which elves (in most settings) don't.

That's why certain settings (Middle Earth, basically) paint elves as a race in long-term decline, fighting a rearguard action against being completely supplanted by humans.

Ditto. Think about the problems long lived whales have.

Every D&D type game I get involved in I think of as being "Middle Earth" like. Like in the Star Trek Federation it just seems like there are soo many humans running about.

[Slayn82]

These are some great answers guys.

Now I've got plans for some Aztec-type wood elves - should also deal with the problem of wood elves always being too passive, in my eyes. Always preferred the wild side to the hippie stuff.

Liking the dwarf fungi thing. Also the "trading with above ground factions" is what my mind initially went to, but that leaves you cripplingly dependent on outsiders and neuters the main advantage of living in a mountain (protection for a siege).

Dwarfs with Goats and Fungi should make the best cheese. Also, have you ever seem the terrace planting system that terrace farming ancient people, like Chinese and Inca developed to take advantage of mountainous terrains? The mountain is covered by series of steps, to slow soil erosion and facilitate the irrigation. Asian people grew rice, wheat or barley, Mediterranean grew vineyards and olives, and Inca grew corn and Maize. Outside of the farming season, those terraces would make a series of lines to defend the terrain against invaders, taking advantage of heavy crossbow emplacements. Also, the well delimited steps would make it easy for distinct different dwarf clans own parcels of those terraces.

Socially, I envision Dwarf societies as a mix between Imperial Chinese clans and Medieval Swiss bankers/mercenaries. The Chinese reverence to ancestry and the adoption of testing to select elite bureaucracy, meeting the Swiss strong geographical defensive advantages, large militarization, intensive trading with close kingdoms.

On Elfs, I see them as a society of isolationist survivalists. Their civilizations have fallen, they retreated to isolation and don't have high density populations, except in places where the feywild gets close to the prime. Their current way of life depends of the preservation of natural resources.

In practice, their forests are well managed environments. Larger trees provide overall concealment, nuts and wood for crafting, and serve to support parasitic plants that grow fast and provide forrage, string, food, licorice and medicine. Elves also practice grafting on their trees, allowing the cultivation of sweet and sour fruits.

Open clearings deep in elf territory serve for both cultivation of crops and, after the harvest, as animal pasture, with a mixed planting of food and forrage. Other edible roots are planted in the ground, amid the fallen leaves of larger trees. Elves employ preferentially biological control in their crops, so carnivorous birds, beetles, spiders and frogs are abundant near those secret gardens. Those are also sometimes employed as a food source.

Small groups of elfs, up to a couple dozen, are responsible for cultivation a territory, spread through the forest. These groups also serve as scouts, watching intruders until more experienced leaders arrive to deal with them and adding their own arrows in case of things turning out ugly.

[Berenger]

Liking the dwarf fungi thing. Also the "trading with above ground factions" is what my mind initially went to, but that leaves you cripplingly dependent on outsiders and neuters the main advantage of living in a mountain (protection for a siege).

The same is true for every fortification - castles and walled cities are dependent on supplies coming from "outsiders", too. This doesn't make them useless. They just have to stockpile enough food to last for a few years, which plays into basic dwarven virtues like order and preparedness.

But why can't there be dwarven farms in the valley beneath the mountain, or terrace farms in the hills, btw? I mean, just carve a few runes in these walls and you are ready to go:

[LibraryOgre]

A better question would be, "why haven't they completely died out?" Slow breeding is an absolutely crippling evolutionary disadvantage, unless you have some pretty foolproof ways of avoiding predation or other violent death, which elves (in most settings) don't.

That's why certain settings (Middle Earth, basically) paint elves as a race in long-term decline, fighting a rearguard action against being completely supplanted by humans.

It's a matter of differing strategies. Orcs are r-strategy... lots of young, and assuming one will survive. Elves are K-strategy... low numbers to which a lot of resources are devoted.

[CharonsHelper]

Do note that this is possible. The native people of North America did to this great success, to the point that a well tended region could easily support thousands of people. In effect the "forest" wasn't a forest at all, it was a massive garden that the people tended, nurtured and intentionally grew and managed, often using fire to clear underbrush and other unwanted plants.

They certainly weren't the only ones. Prehistoric peoples around the globe did this - especially in more temperate climates.

However - the same area still can only support a fraction of the #s as with true farming/cultivation, though certainly more than a true wilderness.

[Beleriphon]

They certainly weren't the only ones. Prehistoric peoples around the globe did this - especially in more temperate climates.

However - the same area still can only support a fraction of the #s as with true farming/cultivation, though certainly more than a true wilderness.

Depends, it also doesn't require as much time actively cultivating the land once all the trees are planted. You haven't have to plan apple trees again every season, you just have to go collect the apples. So one of the benefits of this method is that the people using it actually have some what more free time, especially by supplementing the silviculture with hunting. One has to remember as well if you aren't planting you don't necessarily need beasts of burden (which means you don't have to feed them). So the gross tonnage of food might be less, but the net result can similar to conventional agriculture because you have less bodies to feed.

[CharonsHelper]

...but the net result can similar to conventional agriculture because you have less bodies to feed.

The lower population was my point. I wasn't trying to weigh in that it was inherently an immoral system or some such. Just that it couldn't support nearly as large of a population given the same acreage - which we seem to agree on.

Since the OP was about limitations on elf population due to a lack of cultivated lands, I figured that the smaller population for the same land mass was a point to bring up.

[ellindsey]

My campaign world has significantly different laws of physics which permit vast underground civilizations to exist. Above-ground plants absorb light for energy, as in our world. Underground plants absorb darkness for energy. These have the beneficial side-effect of weakly illuminating their surroundings, accounting for all the strange glowing 'fungus' you see underground. Dwarves cultivate these dark-eating plants in vast gardens, as well as using them for illumination in their underground cities.

I also assume that the forests which the elves inhabit are actually vast cultivated gardens, full of long-lived fruit and nut trees and useful herbs and plants, with carefully managed populations of game animals. A human who wanders in will see a chaotic forest, but someone who knows what to look for will see an ecosystem that is as artificial and managed as a human farm. Elves, being very long-lived, tend to create systems that will be productive for generations, rather than a crop that is grown for a season and then harvested.

Elves are long-lived, though not actually immortal. They also reproduce very slowly, and their children take a long time to mature. Their garden-forests also take a long time to get to perfection, and they don't like to spread outside them much. This does mean that they take a long time to recover from wars, their populations take a long time to bounce back, and their carefully managed forest habitats also take a long time to rebuild if destroyed.

[Beleriphon]

The lower population was my point. I wasn't trying to weigh in that it was inherently an immoral system or some such. Just that it couldn't support nearly as large of a population given the same acreage - which we seem to agree on.

Since the OP was about limitations on elf population due to a lack of cultivated lands, I figured that the smaller population for the same land mass was a point to bring up.

The point I was making is that you can produce a similar amount of food using silivculture and garden techniques because there isn't the necessity of feeding animals like oxen from your harvested crops, since there aren't any beasts of burden to feed in this setup. Also, pound for pounds many nuts produce more calories by a fairly wide margin than grains.

[Slayn82]

The point I was making is that you can produce a similar amount of food using silivculture and garden techniques because there isn't the necessity of feeding animals like oxen from your harvested crops, since there aren't any beasts of burden to feed in this setup. Also, pound for pounds many nuts produce more calories by a fairly wide margin than grains.

I agree with this line of thought. Also, insects offer more protein per forrage than other sources. Add birds, rabbits, fish and occasionally meat from game, like boars or veal, and they get some pretty good diet. Still, I have this idea of Elfs having an sweet tooth, making licorice and using Honey, Mapple and Fruit Syrup, producing sweet nuts and candied larvae for long storage. Also, lots of carrots, eggplants and potatoes. But for their needs of Flour, maybe bitter cassava roots.

[Beleriphon]

I agree with this line of thought. Also, insects offer more protein per forrage than other sources. Add birds, rabbits, fish and occasionally meat from game, like boars or veal, and they get some pretty good diet. Still, I have this idea of Elfs having an sweet tooth, making licorice and using Honey, Mapple and Fruit Syrup, producing sweet nuts and candied larvae for long storage. Also, lots of carrots, eggplants and potatoes. But for their needs of Flour, maybe bitter cassava roots.

Almond flour is a good alternative. Plus it tastes pretty good.

[CharonsHelper]

The point I was making is that you can produce a similar amount of food using silivculture and garden techniques because there isn't the necessity of feeding animals like oxen from your harvested crops, since there aren't any beasts of burden to feed in this setup. Also, pound for pounds many nuts produce more calories by a fairly wide margin than grains.

That I sincerely doubt.

Farmland averages approx. 20,000lbs per acre of land, which is nearly 1/2 lb per square foot.

I don't know how much food you could get out of a garden/forest, but it's not going to be even a fraction of that. Sure - nuts get more calories per weight - but not per acre. An almond farm (that's with pruning/spinklers/pesticides etc.) gets about 2,670lbs per acre. Almonds are high calorie for their weight - but they're not 9x as much as average. A garden forest is going to be less efficient than that. (More mixed crops.)

Now - for the labor involved, the garden forest is probably pretty decent. (Though I still doubt that it stacks up to cultivation.) But food/acre, you're getting a fraction as many calories.

The most efficient calories/acre are grains & potatoes. (I believe that rice is actually far and away the most efficient per acre - but it takes tons of water and only grows in certain areas.) That's the reason that every farming civilization was based around them.

[VoxRationis]

This is assuming that the trees being tended are akin to those available in real life. An elven culture may have bred them far more than we have (since an individual "farmer" would be able to select through more generations). Wheat is incredibly far-removed from its ancestors owing to intensive breeding; a tree in an elven forest might be similarly far-removed. I'm not sure we have good data on how effective silviculture could be (beyond obvious physical caps like the amount of solar energy incoming to a given area).

Edit: Similar things could be said for dwarf/Underdark populations. Hypothetically, a more energetically productive geothermal well could exist, as well as more productive chemosynthetic species, especially once selective breeding is taken into account.

[Slayn82]

If we start throwing those hard caps in the amount of food produced by Elven Forests, you will discover it can't realistically sustain all the monsters around. There needs to be some degree of Fantastic elements to explain that ecological web when you have superpredators like Trolls and Wyverns around. Maybe Elfs make elaborate rituals to bring the Fey to their domains so the Faeric magic allows the production of crops increase massively, and its hard to convince the Fey to come where trees are cut down. Plant monsters could be the result of mismanaged crops.


We could also have Dragons depending of major animal migrations for food, either staying in a single spot to feed and sleeping the rest of the year like bears, or going away to other places where food is more available, like whales. A Dragon interested in a rival's territory could need massive intake of calories, and start consuming nearby herds and crops from civilized lands,spreading a famine.

[Darth Ultron]

Agriculture is artificial. The crops and animals we eat today, and even the ones they used in the Middle Ages, Dark Ages or other historical ages, where made by humans. Wild plants and animals are noting like the ones used for food. For Example: Corn(aka maize) once grew only inch long cobs, but today we enjoy corn on the cob that is several inches long. This is not by accident.

Now a race living in the mountains, woods or underdark would take the plants that grown in those places, domesticate them and turn them into plants unknown here on Earth. They would make the wild plants into food plants. The same is true of animals.

Humans on Earth domesticated selected animals and plants, but another world might not make the same choices. Dandelion's are a weed on Earth, but another world might pick it to domesticate. This is even more true for animals and plants that live underground.

[Aeson]

Edit: Similar things could be said for dwarf/Underdark populations. Hypothetically, a more energetically productive geothermal well could exist, as well as more productive chemosynthetic species, especially once selective breeding is taken into account.

You could go that route, sure.

Another possibility for settings where naturally-occurring magical energy is reasonably abundant in at least some areas is for there to be at least one lifeform capable of converting magical energy into chemical energy in a parallel of sorts to photosynthesis. Such a lifeform could form the basis for an ecosystem in regions where photosynthesis and chemosynthesis are not realistically possible on a scale capable of supporting the ecosystem under the conditions prevalent within the region.

This is assuming that the trees being tended are akin to those available in real life. An elven culture may have bred them far more than we have (since an individual "farmer" would be able to select through more generations). Wheat is incredibly far-removed from its ancestors owing to intensive breeding; a tree in an elven forest might be similarly far-removed. I'm not sure we have good data on how effective silviculture could be (beyond obvious physical caps like the amount of solar energy incoming to a given area).

The length of a generation is much greater for most trees than for wheat; even fast-growing trees tend to take several years before they begin to produce fruits, nuts, or seeds. Unless the time between the 'present day' and when elves began cultivating trees is significantly greater than the 'present day' and when humans began cultivating grains, it is unlikely that the trees cultivated by the elves would be even as far removed from their ancestors as the grains cultivated by humans.

Much more likely, given that we are talking about fantasy settings where magic exists, is that the elves are using magic to increase the food production of the region, have some form of symbiosis or partnership with a species/race which uses magic to increase the region's food production, or are living in a region where naturally-occurring magical phenomena permit much greater food production than would be the case in the real world.

Also the "trading with above ground factions" is what my mind initially went to, but that leaves you cripplingly dependent on outsiders and neuters the main advantage of living in a mountain (protection for a siege).

The same is true for every fortification - castles and walled cities are dependent on supplies coming from "outsiders", too. This doesn't make them useless. They just have to stockpile enough food to last for a few years, which plays into basic dwarven virtues like order and preparedness.

Assuming the siege comes from a state on the surface:
Remember that it is often the case in fantasy settings that subterranean species like the dwarfs have extensive tunnel networks which connect to places all around the mountain in which their settlement(s) is (are) found, and sometimes spreads throughout an entire mountain range, continent, or world. Unless you can block most of the significant surface access points or unless you can deny a particular settlement access to most or all of the tunnel network, effectively besieging such a settlement is likely to be problematic - even a smallish mountain can cover hundreds of square miles, and once you start looking at tunnel networks spanning a mountain range or continent the problem of besieging the settlement starts to be closer in scale to the blockade of France in the Napoleonic Wars or of Germany in the World Wars than to a traditional city or fortress siege, or even a great many traditional city or fortress sieges.

For that matter, since dwarfs tend to be depicted as skilled miners, stoneworkers, and tunnel fighters in fantasy settings, denying a dwarf settlement access to the tunnel network is likely to be problematic. Their tunnels are likely going to be difficult to collapse, and on top of that they're able to dig out or bypass collapsed or filled-in sections relatively quickly. Worse, they, at least in theory, hold the advantage in the tunnels on a man-for-man basis and probably also know the tunnel network better than you do.

[Hawkstar]

Why yes, a wood elven forest can only support 1/20th the number of humans on the plains. Fortunately for the Wood elves of the forest, one of them is worth 20 of the humans on the plains.

[Bohandas]

B] Does living in a forest put a hard limit on the local wood elf population? Can it support as many people as human cities drawing food from farmland can?

That depends on the size of their divine spellcaster demographic. The lv.0 cleric and adept spell Purify Food and Drink opens up poisonous plants and rotting carrion as workable food sources

[Storm_Of_Snow]

For a), well, not every Dwarf lives below ground - farming the surface lands around the mountain that their hold is located in is an honourable profession (and there's contracts for the farmers and their customers). Plus there's always other races who'll pay well for Dwarf-made goods, hire Dwarf engineers for construction and so on, which means residents of the hold can buy in foods (and other goods) the hold's territories can't produce. Add in hunters (and even predator animals can potentially be used for food, although Troll's almost certainly off the menu), fishing etc and you're probably about there.

Alternatively, they have underground farms, and the reason there's no Dwarf mage adventurers is that they all stay in the hold to make sure there's magical sunlight to grow the crops (plus there's a lot of D&D spells that would be very good for rescue in a mining accident). And maybe stone to flesh can turn chunks of mining spoil into a decent quality steak, which both gets rid of an industrial waste material, and (eventually) produces fertilizer for other crops they might want to grow.

[hymer]

Some thoughts on how I tend to handle these things:

A] How do Dwarves in mountain kingdoms eat? More importantly, how do they make alcohol? Same goes for every underdark race.

In most of my campaigns, the dwarves have methods for subterranean agriculture, but they much prefer to trade for grain, greens and livestock. It's far more efficient for them to mine and/or smelt and/or fashion something and sell it for the money needed to buy food. It also reduces the need to defend large, underground areas from incursions. As such, dwarves tend to do much better with a nearby agricultural centre near their cities. But humans and halflings are usually well aware of how lucrative trade with dwarves can be, and are happy to avail themselves of such opportunities, meaning that towns nearby tend to happen quickly.
As for the Underdark, I didn't create it, and I don't feel compelled to come up with answers for it. I've yet to have a player ask the obvious questions, but if one did, I'd joke about it and mock the Underdark for a bit and then move on.

B] Does living in a forest put a hard limit on the local wood elf population? Can it support as many people as human cities drawing food from farmland can?

There's always a hard limit somewhere. Eventually you'd have to stack people for the population density to increase. But yes, I generally have sylvan elves have lower population densities. But a given forest can support many more elves than humans. Elves need less sustenance to begin with, and their presence is much like that of a druid or other nature magician: it helps the area flourish, improving the fertility and output through techniques that are similar to gardening and game warding. They also have magical means of warding off certain minor catastrophes.

C] If elves are immortal and never age beyond the point where they can reproduce, why haven't they overtaken the planet?

My immortal elves are usually made by the god of nature. They do not change through evolution, but evolve instead on a personal level. This is why drow look so different from the other elves, e.g. It also means that elves seek an equilibrium, not the multiplicity associated with Darwinism. When there are many of them, they slow their procreation instinctually and consciously, and when they are few, they speed it up.
In more Tolkien inspired thoughts, the elves could have an upper limit to how many children a woman could bear. Giving birth is hard on the spirit, and so they only have about three or four usually, and these need not procreate between fifteen and forty like humans tend to. This slows down population growth further. Wars will deal with the surplus, as expanding population inevitably leads to conflict with others.

[eru001]

C] Birth rates are important and length of time to reach maturity are as well. More important than longevity. one elf might trounce one human due to weight of life experiance. But in an war of attrition. The elves will lose every time, simply by virtue of humans being able to replace casualties much more easily. Humans go from nothing to potential recruit in about 16 years (medieval) or 18 years (modern). Elves do the same in 80-100 depending on the setting.