"Лиственная порода" and "хвойная порода" are antonims, so a specie can't be both.
"Лиственница - это хвойное дерево" - correct
"Лиственница - это лиственное дерево" - incorrect

That means, the first phrase has logical conflict. Sentence "Хотя хвойное дерево" is built incorrectly - it has no subject.

The second sentence is ok.

Actually conifer shedding its needles doesn't seem normal from Russian perspective, we usually consider conifer as an evergreen tree. And a larch is not that popular in our culture. If you ask russians "Please, name a conifer that first comes to your mind", spruce would probably win, pine would be second and larch would be third at best.