Biomes/natural Vegetation: Needle-leaf Evergreen Forests
Needle-leaf evergreen forests are largely comprised of straight trunked, conical shaped trees that have comparatively shorter branches with narrow and small needle like leaves. These forests are composed of conifers predominantly. Where the needle-leaf forests are evergreen, they provide continuous deep shade to the ground, therefore, the lower layers of vegetation are either absent or sparse (Veregin 2005). Only a thick carpet of mosses can be found below the needle-leaf biome. There are very few species that can be found, however the large tracts of the vegetation have one or two species.
According to the World Vegetation Map, this natural vegetation is mainly found in two continental belts of Eurasia and North America. The needle-leaf evergreen forests extend the landmasses from west to east in 45° to 75° latitudes. Boreal forest biome (Taiga) has needle-leaf evergreen forest (Veregin 2005).
The evergreen forests of Western Siberia, Europe and North America consist of the evergreen coniferous vegetation, such as fir, pine and spruce, whereas, eastern and north-central Siberia has larch vegetation which sheds the needle leaves in winter and form a deciduous forest. The forest can be found in Cascade, Sierra Nevada and Rocky mountain ranges in western North America and higher plateaus in south western American states. In Europe, this biome can be found in all of the higher mountain ranges and Scandinavia.
Podzolization happens as a result of acidic soil solution that is produced under the needle-leaf trees or conifers (Veregin 2005). The primary soil order associated with Boreal forest or the Taiga biome is spodosol. The biome corresponds to the regions with long, severe cold winters (more than six months of below freezing temperatures) and short summers with mean precipitation annually is 15 to 20 inches. With this climate, the trees can reach to the height of 20-60 ft. at maturity (Veregin 2005).
It is interesting to see the evergreen conifers of California and British Columbia, where heavy orographic precipitation and high humidity have given rise to the world’s densest coniferous forest and world’s largest conifers. Species of Redwood tree and big tree can attain a height of 100 meter with 65 ft. girth.
Reference:
Veregin, Howard. Goode's world atlas. Rand McNally, 2005.
