Do trees add or detract from a home's value to potential buyers?

It depends on the buyer.

Some people live trees in back for shade.

Others hate too many trees out front.

We purchased a house with 3 large pine close to front of house. They were a mess. We purchased the house and we knew the trees were going do 5 trees cut down was our first project.

It depends on how many there are on a property, if they're decently spaced, and how well maintained they are. Too many poorly maintained trees are a detraction form the homes' value.

If the trees are close to the house, they detract. Leaf cleanup, gutter cleaning, etc. If they are large, even more so, as they can do sidewalk and foundation damage, are prone to have branches blow down, and are a pain to clean up after if deciduous. For a house resale, new fruit trees and evergreens are a plus, but the big ones gotta go. A Rhododendron will defy death and has a huge root ball. Don't plant it close to the house.

Go out and buy that huge DF and plant it in your yard.    Yours would be a stick because they can't plant them that big.  Time is something no one can buy.  So there is a value that is unmeasurable.  That goes for the maples if they are really big.

 Cleaning up is a human construct.

It is so easy to get rid of the tree.It is IMPOSSIBLE to replace.

If there is a potential buyer, then perhaps that is what they wanted. It is a minor amount of work to clean up.  For the leaves and debris that does not blow away, that eventually turns into dirt.

There is no upkeep for the trees.They just grow. Otherwise, there is nothing special about her house.  But it is "more special" than the neighbors.

My insurers do not like trees close to property because of the risk of damage by roots. In that sense they detract if you don't want to pay higher premiums.

not if someone wants to plant a garden

Depends if a person likes trees or not.

There are people who will buy the house specifically because it has those trees. She may want to keep the trees and get rid of the gutters and chop up the leaves with a lawn mower. Blow them out of the flower beds with a lawn blower.

In general, trees add a great deal of value to a property.  They offer beauty, texture to the landscape, shade, protection from wind, nutrients for the soil, erosion control, and a habitat for wildlife.  A home with mature trees would normally fetch more money.  There are lawn services as well as attachments to power mowers and lawn tractors which make short work of fallen leaves.