Why do all the tree shoots die?

[RolmanIronman]

I have started a game in which it is -10ºC in Winter. The Trees are Dead, OK.
In the New Spring I have started planting trees in crop fields. But sometimes when I look at the field some trees have disappeared ... many have already disappeared, autumn is coming and they have barely grown to 25%, winter is coming and they will not have reached the minimum 50% to give wood.
Why do the trees disappear?

Por si algun Español sape:
He comenzado una partida en la que en Invierno hay -10ºC. Los Arboles se han Muerto, OK.
En la Nueva Primavera he comenzado a plantar arboles en campos. Pero a veces cuando miro el campo algunos arboles han desaparecido... muchos ya han desaparecido, esta llegando el otoño y apenas han crecido al 25%, va ha llegar el invierno y no habran llegado al 50% minimo para que den madera.
Porque desaparecen los arboles?

[Astasia]

Plants have a lifespan after which they will die even if they haven't reached 100% grown. For like a pine tree that is 180 days, or 3 game years. Below 10C they grow slowly, below 0C they don't grow at all, if your map is pretty cold most of the year like on a tundra there's a good chance trees will never grow enough to be harvested before they hit their max lifespan and die.

Some animals like thrumbos and alpha beavers also eat trees.

Colonists can't grow any plants in the 3x3 area around a tree and if you try to place a growing zone there they will automatically cut the tree to make space for the growzone.

Those are the reasons I can think of offhand for specific trees to "disappear."

[RolmanIronman]

It is no reason. The fields are 5x30 five fields together, one after the other, one of them made of bamboo, which does not need space and everything disappears. Would Toxic Ash affect this?

[Astasia]

Toxic fallout kills all plants on the map that aren't roofed. Poison ships kill all plants within a radius around them.