I’ve been writing a fair bit of fiction lately, and one question has been driving me nuts: what kind of wood is used for fireplace logs?
That is all. Thank you.
Hardwood. Usually oak, but any hardwood that is available will do. It needs to be seasoned, which means that after it is split it must air dry so that the moisture content is lowered.
Soft woods like pine, poplar, spruce, et. al. burn too fast and too hot, and create too much creosote to be good fireplace material.
Generally, whatever kind of wood is cheapest and easiest to get. If you’re heating a cabin in a pine forest, you’ll cut down pine. If wood is heavily in demand and expensive, there’ll be a tendency for whatever local type of wood that regrows fastest to become the predominent fuel. If you have a choice, you might pick a type of wood that’s comparitively easy to cut down and split.
As for quality, there are some qualifications: pine and fir tend to be easy to start and burn quickly, hardwoods tend to burn slower and last longer. A few kinds of wood are really poor quality (hard to start, smoky, bad smelling). Others would be wasteful to use as fuel, such as high-quality hardwood and fruit and nut bearing trees, although these might be used sparingly for the scent they give off. Some types of wood such as mesquite* are used almost exclusively for the scent and aroma they bestow on smoked foods.
*mesquite is a bush or shrub, but I use the term wood broadly here.
Coal. is best 
Having lived in a mining town, I grew to love coal fireplaces. We only ever put wood on as a novelty. One time, I threw a big lump of Yellowbox wood onto an already hot coal fire - it melted the grate!
But yeah, “Box” wood is really good stuff for a fire.
All good answers so far. A lot wood depend on where your fictional wood burner lives. In the NE USA, there are many choices with hardwood preferred excepting Tulip poplar and cottonwood (regionally called quaking ash ). Prior to hydraulic or other powered splitters, those splitting by hand would eschew hard to split species like hawthorn, sycamore, beech or elm. Large bore chimney owners wouldn’t worry about creosote producers like black walnut, but most “airtight” stove users avoid it. Nice smell though.
Friends in the western states say hardwoods are scarce, so pines and cedars get used.
As Lumpy indicates, the answer is pretty much “Whatever ya got.” Here in Pennsylvania, it tends to be such species as oak, ash, hickory, locust and maple. But we live in one of the best hardwood forests anywhere and are spoiled. In California, it would be a very different story.
Willow, birch and other soft woods burn hot and fast.
The usual fire wood is oak around here. Ash is a fire wood too. For something using a chimney people tend to stay away from resin laden trees like evergreens. Evergreen logs can blow up too. If you plan on cooking in the fire you don’t want evergreen either. Never use poison sumac on a fire, the smoke can cover you with the poison, and it can cause respiratory distress.
WTF? Cite?
It’s all Douglas Fir (gasp – an evergreen) around here. Sometimes alder, sometimes maple. Not a lot of hardwoods in the Northwest, and the ones we do have are generally too pretty to burn.
I’ve seen them blow up and scatter the fire wood a good 5 feet. It’s the resin and the fact they can burn when greener. Lucky it was an outdoor fire and it wasn’t dry out. I’m not searching the internet for proof of what I witnessed. My two eyes are good enough for me.
Oak logs will warm you well, if they’re old and dry;
Larch logs of pinewoods smell - but the sparks will fly!
Beech logs for Christmastime; Yew logs heat well!
“Scots” logs it were a crime for anyone to sell.
Birch logs will burn too fast, chestnut scarce at all;
Hawthorn logs are good to last if cut in the fall.
Holly logs will burn like wax: you should burn them green;
Elm logs like smouldering flax, no flame to be seen.
Pear logs and apple logs - they will scent the room;
Cherry logs across the dogs smell like flowers in bloom.
But ash logs all smooth and grey - burn them green or old.
Buy up all that come your way! They’re worth their weight in gold.
Um, I just realized that the OP sounds very strange with this crucial detail missing: I’m writing a story that takes place during winter in Colorado. :smack:
Colorado?
Pine. I heated for 10 years with it.
It warms you twice. Once to collect it, and once to burn it.
Thanks! And thanks to everyone else who made a go of it as well, especially Malacandra’s especially spirited entry.
Can you explain this?
I’ve heard this saying before. It means the exertion of collecting it also warms you.
This particularly applies to pine, which burns quickly, so you go through a lot of wood in a relatively short period of time.
Bingo.
Stocking 6 cords of wood for the winter takes a lot of work. Just bringing in a weeks worth of wood into the house was a lot of work. I sort of miss it. But am glad to be rid of the mess.
We had 15" of snow Monday and Tuesday. Summer is still a bit far off.
No snark intended, but ‘collecting’ is a bit of a quaint understatement here in my opinion. It isn’t as though you can just pick up a cord of firewood like picking blackberries. It has to be cut and split, and that is work in a sense that I fear is being forgotten. I’m sure you knew this-I just wanted to point it out lest some rookie infer less work than is actually required.
Hostile Dialect it seems you’d be dealing with softwoods, so;
Best Choices
Slash Pine
Pond Pine
Western Larch
Longleaf Pine
Good Choices
Yew
Tamarack
Nut Pines (Pinon)
Shortleaf Pine
Juniper
Loblolly Pine
Douglas Fir
Pitch Pine
Red Cedar
Norway Pine
-From Heating with Wood, by Larry Gay. I’ll leave it to you research which of these are indigenous in the area in which your story is set.
Also there was another column labeled Acceptable Choices, but I’m not copying it-Dopers don’t write stories about merely ‘acceptable’ fires; Dopers write stories about exemplary fires. 
We did a lot of felling, loging and splitting. But we also bought a lot. When we bought it it was still a lot of work. It would get dumped in the driveway, we would then load up the bucket on our tractor with wood, drive it to and take to where we would stack it. Even that was a lot of work.
And I’ll confess. We sometimes purchased an oak pinion mixed cord. The oak was trucked in from Missouri. But all local wood was of course pine.
We had the biggest Vermont Casting stove you could buy. It did the job, but it was quite a bit of work. And messy too.
A fire would just barely last through the night. But we didn’t keep it going all day when we where at work so I had to re-light it when I got home.
To the OP, does the fictional charactor have a chainsaw? Splitter?
He’s not really the type to habitually do his own logging or anything. He and his friends might all get together and do it once because it sounds interesting, but for the most part he (or they) would be buying it by the cord. He might have a chainsaw around for eccentricity value, but whether he would actually use it is a different story.
I’ll do my own pine research as well, but can anyone who has burned a lot of pine describe what it smells like, how it crackles, what the fire looks like, how much you need to warm up an average living room for a night, and anything else that comes to mind about it?
Thanks again for all of your helpful answers.
ETA - The story isn’t even about firewood at all. It started out as a minor detail that I didn’t want to get wrong lest I alienate cold-climate readers. But it’s become such a major focus of my research that I’ve decided to name the story “Cordwood.” 
If he’s got money, and is burning firewood for esthetic rather than heating purposes, he may well be burning aspen logs. Very pretty, and burns well, although he’d probably have some fatwood or cedar to start the fire with. Aspens another softwood, not only plentiful in Colorado, but almost emblematic. If you were to begin a story with “He threw a couple more of the nice aspen logs on the fire”, a Colorado location is already implied.
As far as pine, even well-aged it burns with a lot of character. Fireplace screens are a requirement, not a nicety. If you were to throw in an un-split log with a substantial knot deformation, I suppose you could get a substantial ‘pop’ and scattering of material (not an explosion!), but more often well-split and seasoned pine will burn with pops and spits, crackling, and make short-lasting but very hot coals. If you’re burning pine with any frequency, you will see your grate deform – the metal gets soft in the middle and droops. You’ll also have to get your chimney swept, usually annually if you’re heating with pine. Pine lights easily, but burns fairly quickly, so you have to mess with the fire more – pushing the unburnt ends towards the center of the grate, or re-adjusting the logs to burn more evenly. I’ve often seen pine logs, initially stacked nicely and burning well, fall together and nearly snuff themselves out.
I’ll be looking for the book ‘Cordwood’.
Long post deleted to better address the OP….
In the Rockies of Colorado, at say a summer cabin you can walk within 100 yards or 100 feet of your cabin and find firewood for a day or two. Doesn’t really matter if it’s pine or aspen, provided it’s not rotted, somewhat dry, and burns.
It also depends on how many times you’ve collected wood in the area.
A chainsaw or axe helps a lot.
It’s not so easy in the winter though. Everything that has fallen naturally is gone to you. Ass deep in snow is not a fun way to collect firewood. Trust me on that one.