Hammond said: "I know that many people living along the line of the route are worried about the perceived impact on their local landscape.
"The two million trees we will plant will help to reduce the visual and sound effects of the line, offset some of the carbon impacts, and create new habitats for local flora and fauna along the line," he said.
The Department for Transport said the trees and shrubs would be planted to create a natural look rather than in artificial-looking rows and would be developed in a way that supported local habitats and wildlife.
Hammond also pledged to work with local communities along the route on further measures to reduce environmental impact of the line.
A Woodland Trust representative said: "Whilst the planting of two million trees is a great contribution towards increasing the UK's minimal native woodland cover, it is important that this isn't seen as a token gesture in what could potentially see the loss and fragmentation of existing woodland habitats, which are of far higher conservation value and in some cases irreplaceable.
"Furthermore it is essential that the trees planted are not only native, but are also planted and managed sensitively as a high percentage of trees planted by roadsides simply die off."