Thought birch maybe, then saw hickory...

Pine or spruce

Test how hard the wood is if soft it is pine...harder could be birch or hickory

That's pine and in my opinion the gouges in the lower center of the picture lead me even more to my opinion.

This is a very interesting and unique floor...is it a refinished original in an old home?..has it been stained?..it really is incredible!

In some old homes the sub- flooring looks like this

It could be a spruce; is this european?

Ugh. Knotty pine.

Just saw a post with knotty alder that looks like this...

Maybe Cypress, post a close-up floor height photo at a angle.

@ulisdone nope, it's in Colorado, USA.

@btydrvn we just purchased the house which is 30 years old. I'm not sure when the floor was installed but it looks like it hasn't been refinished in a long, long time. :) There is some kind of stain or poly on it which has yellowed over time in some places near the windows.

Could be spruce. Call in a flooring guy to find out what your options are. Nice rustic look for Colorado.

Is the surface smooth ?...30 years ago they used the cheapest wood available without concern for flaws as sub flooring...usually that is pine...but the holes would have been dented or open..the knots would be black from outdoor storage as this is probably construction grade material at that time...lived in aspen for years and saw a lot of this in the little refurbished victorians..

The victorians in aspen were hundreds of years old ,of course..but the wood colorations were similar

If, you have checking in the knots. The specie is Spruce. No checking, it’s cypress. Pine has large knots. Not enough red or pink to be red pine And the knots are small.