Whilst covering this religious theme, the majority of the painting is in line with his reputation as predominantly a landscape painter, first and foremost. Other than the saint and the animal in the foreground, the rest of the scene is purely dedicated to the green tones of the Bavarian countryside. In the background is, again, the bright sky which allows light into the rest of the composition.
Another common feature used by Altdorfer was to frame his content using tall trees, particularly as most of his paintings were vertically designed. It was his drawings which followed the more standard layout for landscapes of being horizontal. Those would then use other methods to frame the main content within the scene. The artist would always choose fairly slim trees for the two sides to avoid them taking up too much space across the scene, something like a pine tree would have been ideal.
Saint Jerome, as with many other saints, have been covered by countless numbers of artists over the centuries, most frequently during the Renaissance. Religion was even more prevalent and intwined in society then than it is now and most of the donors would specifically request commissions that contained religious themes and iconography. They would not be general paintings but more likely a fresco to be placed in a specific part of a building.