Cutting Down Trees

For this past couple of weeks, for some reason, very old and very big trees are being cut down or trimmed.
Is this something that must be done towards the goal of being a City?
I highly doubt it is that reason. All those trees that have been cut down are very huge and very old tree. Those trees has been there even before I was born.
Why cut them down? Is this because a City doesn't need trees?
My town. It is now call a City. But it doesn't look like a City.
There is a few abandoned projects all across my town. One is the "Ghost City" which is now starting to pick up it's pace as a few shops has begun to open for business.
A old abandoned project located beside a school. The building has been abandoned since don't know how long. And it is still abandoned until today. And a couple more places where buildings are half-build and abandoned with no indication that they will be finished in the near future.
My town used to have paddy fields. Now, all those paddy fields are buildings now. Although there are still mini pockets of secondary forrest left in the outskirt of town, soon those will be gone too. More Residential Area has been planned. And somewhere in New Town, they are building more Residential houses. That's why it is call New Town.
Soon, Old Town will be a pale shadow of it former self.