Conifer forest will appear somewhat darker. On the 1997 set, deciduous forest is a medium grey, while conifer forest is much darker. Conifer forest can look like water on the 1997 set, too. We are lumping deciduous and coniferous forest together. This includes land used for crops, pastures and orchards.
Orchards have trees that are spaced uniformly.
Note that you can often see the shadows of individual trees on roads. It could be a cloud, lettering on the photo, etc. You could measure every square millimeter, but that would be incredibly tedious. A quicker yet still accurate technique is to sample, i.e. measure only a smaller set of all the points on the photos. There are many ways this could be done.