Plant reintroduction helps reestablish ecosystems that have been damaged or reduced by pollution, invasion, construction, or natural events such as fire. Like animal reintroduction, plant reintroduction uses only species that are natural to an ecosystem. In many cases, however, the natural plant has become endangered or threatened. Therefore, the second role of plant reintroduction is to reestablish in nature plant species that have become scarce in the biomes where they belong.
Restoration biology comprises a field of study that focuses on fixing degraded ecosystems. Preparation steps for plants that will be introduced into the environment consist of the following steps:
- seed production
- seed dispersal in the habitat
- monitoring seed germination
- establishment of young plants
- nurturing young plants to maturity
Tree or plant reintroduction requires monitoring to ensure each species establishes itself in its new habitat and can reproduce there. The establishment period lasts a few weeks in which a plant gains a foothold in the ecosystem. To do this the establishment phase consists of a period in
which soil root systems develop, a period of steady growth rate, and then a period of slower growth, called closure, when plants compete for sunlight and soil nutrients. Closure leads to the eventual death of the tree or plant, though this may take many years. During this sequence, meanwhile, the plant life provides nutrients, shade, shelter, and other factors necessary to
the ecosystem.
Tropical forests hold most of the world’s biodiversity, but deforestation of those biodiversity hotspots has been especially hazardous to ecosystems. Tropical forests have therefore become a priority for worldwide efforts to reintroduce plant life to damaged ecosystems. The following table gives examples of plant reintroduction programs now underway in Asia.
The endangered species list contains four different plant groups: conifers and cycads, ferns, lichens, and flowering plants. Reestablishing an endangered plant in its natural habitat employs one of two approaches: complete reintroduction or enhancement. Reintroduction involves recovering seeds from an endangered plant and establishing seedlings in fields or hothouses. Biologists then return the plant to its native habitat. Enhancement endeavors to help plants that are on the brink of disappearing by adding nutrients to the soil or by introducing the same plant from another location. This second choice gives the population greater genetic diversity and so, one hopes, reestablishes a healthy population.
Today plant reintroduction takes place in every biome and in riparian areas, wetlands, and pollution-damaged sites. Plant reintroduction differs from animal reintroduction because it uses genetic engineering and tissue culture to create stronger, long-lived offspring. Plant scientist Carl
Leopold of New York’s Cornell University helped Costa Rica reestablish forests that had been nearly eliminated 50 years ago. Leopold pointed out the additional benefits to the local towns because of the program: “By restoring forests we are not only improving the native forests, but we are helping control erosion and helping the quality of life of the local people.” For these reasons and for the restoration of ecosystems in addition to forests, plant restoration is a high priority in saving biodiversity.
