"amount of trees" is a perfectly correct and usable phrase in written English.
You could use it anytime you want to refer to the collective number of trees in a particular area or context. For example, "The park has a large amount of trees, making it a popular spot for picnickers."
"We had a tremendous amount of trees down from the weight of the snow.
"This means designing forest policies to match the amount of trees cut down due to the expansion of plantations".
Hanson's recent dismissal of climate change as a "BS... money-making racket", disproven by the "amazing" amount of "trees and growth" she spotted out the window of her Jabiru Ultralight while on the hustings in rural Queensland.
For example, the app will tell you that the carbon output during your drive to Philadelphia equals X amount of trees.
The variables most predictive of the likelihood of restoration were the percentage of ground surface covered by grass, the amount of trees and bushes visible from the given viewing point, and apparent park size.
Primary determinants are the structure of the forest, the amount of trees, tree density and the characteristics of the combustible fuel.
We have large amount of tree debris, making the sidewalks impassable".
All of the biodiversity certifications use vegetation structure and complexity (like amount of tree canopy cover and native tree species) as an indicator of habitat quality, which in turn is an indicator of biodiversity.
We investigated breeding bird diversity in three types of housing development with approximately the same amount of tree cover.
A fair amount of tree species (18 of 25) showed a significant influence of a CI to diameter increment.
Forest thinning removes an amount of tree carbon which is not usually a detectable change in forest cover fraction.
