Forest ecosystem restoration is often a costly endeavor, a fact perhaps best known in China, were large sums of money have been spent over decades for afforestation efforts. Still, many parts, while having overcome the most severe problems like erosion and the establishment of any vegetation, are without forest and remain shrub- or grassland with a few scarce trees scattered in-between. Where these still degraded landscapes are in proximity of a few kilometers to more natural forests, a cost-saving method to fully restore forests is possible: the Framework Species Approach (FMA) widely promoted by Stephen Elliott for the restoration of tropical forests in northern Thailand.
The premise of the FMA is to use the free dispersal mechanisms of natural forests, including the actual seeds, but also seed-dispersing animals. Normally the seed-dispersers stay in the forests as the degraded land o
nly has few things to offer. According to the FMA 10-20 framework species (Elliott himself recommends 20-30, but the intrinsically greater diversity of tropical forests should be considered, where 20-30 species is only a fraction of all the species present) are selected, then planted them and throughout the next 2 years repeatedly weeded and mulched. That way dominance over competing shrubs and herbs is ensured. As these species grow larger, they form a dense canopy that shades out most of the competition from
weeds and herbs. Once they produce fruits and seeds, they attract the wildlife from nearby natural forests, which introduces the species not originally planted, but nevertheless part of the forest.
Criteria for Framework Species
Framework Species are not only rapidly growing early successionals with wide crowns, which should make up at least 30% of the selected species, but also mid-successionals and climax species. By initially planting them all together, the succession cycle is somewhat “short-circuited”, reducing the overall time needed to re-establish a natural forest ecosystem, as the later successionals are initially not dependent on mammals and birds to distribute them on the restoration site. However, there are some characteristics Framework Species usually have in common:
- high survival when planted out in deforested sites,
- rapid growth,
- dense, spreading crowns that shade out herbaceous weeds and shrubs
- flowering, fruiting, or the provision of other resources, at a young age, which attract seed-dispersing wildlife
In areas where the soil is still considered to not be fully restored, nitrogen-fixing plants could furthermore be preferred. It should also be noted, that in the specific case of Eastern China, the species traditionally selected, like Oriental Thuja (Platycladus orientalis) might not be ideal for the FMA as they don’t tend to build overly dense crowns, consequently allowing shrubs like Vitex negundo to dominate the area even after a forest has been established, consequently decreasing the chances of other species to grow up in the understory and contribute to a more diverse forest. Generally, however, existing literature and own local research (e.g. through a Forest Research Unit (FORRU)) is necessary to determine the best framework species for different sites.
Furthermore, a survey, ideally with the help of GIS, should be conducted on which areas are close enough to target forests with sufficient seed source (a few kilometers would be sufficient). Areas that are too far away from a target forest could receive the “Maximum diversity planting” treatment, where a nearly full selection of naturally occurring species is planted.
Unit, F. R. “Framework Species Method.” Retrieved 10/15, 2016, from http://www.forru.org/en/content.php?mid=70.
Elliott, S. and C. Kuaraksa (2008). “Producing Framework Tree Species for Restoring Forest Ecosystems in Northern Thailand.” Small-scale Forestry 7(3): 403-415.
Unit, F. R. (2008). Research for Restoring Tropical Forest Ecosystems: A Practical Guide, Biology Department, Science Faculty, Chiang Mai University, Thailand.
Prasit, W. and S. Elliott (2008). “Testing the Framework Species Method for Forest Restoration in Chiang Mai, Northern Thailand.” Walailak Science & Technology 5: 1-15.
Blakesley, D., et al. (2002). “Propagating Framework tree species to restore seasonabbly dry tropical forest: implications of seasonal seed dispersal and dormancy.” Forest Ecology and Management 164: 31-38.
Elliott, S. and C. Kuaraksa (2008). “Producing Framework Tree Species for Restoring Forest Ecosystems in Northern Thailand.” Small-scale Forestry 7: 403-415.