Grafting to save the forests.

Tropical forests (and all other forests) have suffered enormous damage in recent decades. If the current rate of forest clearance in the tropics (estimated to be 150 000–250 000 km per year) continues, they will disappear as a major, large-scale ecosystem in many countries during the 21st century. As a result, a chain of environmental problems, including increased soil erosion, damage to water resources and loss of a terrestrial carbon sink, will occur. Approximately half of the tropical forests are clear-cut for shifting agriculture, and, once cleared, cannot be rescued. The rest of the forests are cut for timber supply and efforts can be made to enable them to recover quickly. In mature fruit orchards of tropical, subtropical and temperate origin, grafting is practiced routinely when a better variety is desired. Accordingly, we propose that at least some of the felled trees in the tropical and temperate forests should be grafted using their own material. Grafted trees resume growth quickly because the sprouts enjoy the welldeveloped root system of the mature trees. Such forest management techniques might generate significant benefits: ensuring genetic continuity; enable clonal improvement (in commercial forests); preserving the mycorrhiza and other soil biota; keeping a huge quantity of root biomass (on average 26% of shoot mass) alive and active; preventing soil erosion; shortening the period of time for forest regeneration; increasing sustainability; reducing CO2 emissions to the atmosphere and increasing its incorporation into biomass; and reducing the dependency on nursery operations, which are costly, and in many developing countries, the technology for high quality forest seedling production does not exist. In countries with low labor costs (which includes most tropical countries), grafting can be practiced on a large scale. A team of grafters might follow the harvesting team and graft the cut trees with shoots from the canopy of the same tree or with selected material. In addition, in specific commercial forests, elite clones can be grafted to retain desired qualities, or individual tree species can be grafted, such as Taxus trees cut to produce taxol. In this way, selected grafting in cut forests could provide an opportunity to manipulate the landscape and to form fragmented forests or open-park forests. The grafting must be done while the cambium is active – spring and early summer in the temperate regions, and most of the year in the tropics. The establishment of this simple method in tropical and temperate forests could help to change the current rate of decline and damage to global forests. Legal, administrative and management measures should be coordinated to facilitate the application of this method.