In North America, you would usually have to travel to the south to go from a coniferous forest to a deciduous forest. Temperate deciduous forests or temperate broad-leaf forests are dominated by trees that lose their leaves each year. They are found in areas with warm, moist summers and mild winters. Temperate coniferous forest is a terrestrial biome found in temperate regions of the world with warm summers and cool winters and adequate rainfall to sustain a forest. I hope this is the answer that you were looking for.
In north america, the direction you would usually have to travel to go from a coniferous forest to a deciduous forest is heading south. coniferous forest are more likely to be acidic in nature than the deciduous forest. the deciduous forest typically has more clay soil and higher ph.