A pocket forest is created by planting native trees and shrubs in close proximity as a means of rapidly restoring native plant species in damaged ecosystems. While forests naturally grow through a primary stage and then a secondary stage before reaching their climax stage, pocket forests are created by a dense planting of climax stage species which grow rapidly in competition for sunlight.
Pocket forests have been embraced by environmentalists as a means of reforesting urban spaces and teaching urban residents about native forest environments. The growing interest in pocket forests was inspired in large part by the work of Japanese botanist Akira Miyawaki, whose "Miyawaki forests" have influenced the development of a variety of pocket forest methodologies adapted to different climates and spacial constraints.
A variety of protocols for site preparation and planting have been developed, all sharing the same underlying principles as the Miyawaki method. The following is an example methodology:
The area to be planted is first covered with a layer of cardboard which is then covered with of compost and allowed to acclimate to local moisture conditions for several months. The covered area is then planted with year-old plant nursery saplings spaced approximately apart. The entire surface area should be planted at the same time with a variety of native species so no saplings of the same species are adjacent to each other.[1] Watering is unnecessary for native plants acclimated to the local environment; although watering for the first few years after planting, and during drought periods, will reduce mortality of individual plants.[2] Pocket forests planted with greater density than commercial timberland utilize edge lighting in addition to overhead lighting to grow faster while absorbing more carbon dioxide per acre.[3]
Three is the minimum number of different species of nursery saplings for planting a pocket forest. The arrangement below of species A, B and C illustrates avoidance of planting the same species in adjacent positions.
A B C A B C A B C A B C A
Miyawaki developed the method as a means of replenishing forest soils by allowing dead leaves and twigs to decompose in a moist, wood-rotting ecosystem.[9] This process may be less successful in drier fire ecosystems where nutrients are recycled as ashes.[10] [11] The dense pocket forest forms a capture mechanism for wind-blown embers, dried ground litter is an ignition source, and the multi-layered pocket forest forms a fuel ladder with wildfire risks in urban areas.[12]