If there are 100 roses in 1 km², then the total number of roses in the forest of 53 km² can be estimated by multiplying the number of roses in 1 km² by the total area of the forest:
Total number of roses = Number of roses per km² * Total area of the forest
Total number of roses = 100 roses/km² * 53 km²
Total number of roses = 5,300 roses
Therefore, there are an estimated 5,300 roses in the forest.