Question about pine reproduction
I have a doubt, and I would like to know opinions about this problem.
On my country, Argentina, there are some human implanted populations of various species of pines, of European origin.
I don't know what species they are. They are cultivated for commercial purposes (I are not one of these peoples).
Those pines are implanted on some rocky, mountainous areas, with rare or not naturally occurring trees (probably due to frequent fires).
Some of these artificial forest are many decades old.
I had a doubt long time ago, which bugs me and I never solved. The question is why these pines do not naturally reproduce, and disperse.
I would expect for these trees to spread his seeds in the wind, and populate the surrounding area, but even as many of these plantations are dozens of decades old, is frequent to see that not a single tree grew outside of the plantation, and the surrounding area is totally wild, never farmed, many never owned by anybody.
What do you think?
Do these pines probably need some specific type of insect to pollinate?
Do seeds may need to be eaten by some animal to be fertile?
May these trees be some sterile hybrid?
May these pines have 2 sex, and being all males or females?