Coppice Systems

Glenn Galloway
CATIE

Many tree species that are planted in the Americas possess the capacity to sprout from the stump following harvesting. This ability enables individuals of these species to survive catastrophic disturbances such as fire or cutting. Coppice sprouts develop from either dormant buds on the side of the stump or from adventitious ones found in the periphery of the cut surface (Evans 1992). Some eucalypt species sprout from lignotubers which are storage structures found at the juncture of the roots and the main stem (Jacobs 1981). When a tree is growing vigorously, the aforementioned buds are suppressed by the basipetal flow of auxins (a plant growth substance) from the upper parts of the tree. When the tree is cut, this flow of auxins is interrupted, allowing the dormant buds to become active and sprout. In many species a large number of sprouts develop on the stump, but gradually this number decreases through a process of self-thinning.

This capacity to sprout is very important for both farmers and industrial operations in many parts of Central and South America. Once the initial investment is made to establish a vigorous, productive plantation, it can be harvested and regenerated from the shoots arising from the cut stumps. Of particular interest to farmers and industrial operations is the high yields of many plantations regenerated from coppice. Coppice sprouts are able to take advantage of the root system formed by the original tree and stored carbohydrates. Thus, the productivity of stands generated from coppice sprouts has often been found to be higher than that of the original stands grown from seedlings (Wadsworth 1997). Coppice does not, however, increase site growth potential (the amount of total biomass produced on a given site), but reaches this potential in a shorter period of time.

A number of precautions must be exercised in order to take full advantage of the capacity of a stand to reproduce from coppice. Improper cultural practices can lead to the following problems: stump rot, a reduction in the number of the potential rotations that can be regenerated from the same stand and production of low quality products. Appropriate practices for managing coppice is not the same for all species and depend, in large part, on the products desired. In the following paragraphs, examples of important considerations and practices to attain well-managed coppice are provided.

Care taken during harvesting is vital to coppice survival and vigor. The stump (or stool) should normally be cut cleanly, low to the ground, without separating the bark from the stump (Jacobs 1981). Stumps with a slight inclination facilitate water runoff, important to disease prevention. Harvesting with axes often leads to undesirable damage to the bark on the stump and leaves a rough, irregular surface that favors water infiltration into the stump. For this reason, where chainsaws are not available, crosscut saws are preferable to hatchets and axes. Examples are provided by Evans 1992 of species which coppice best from stumps greater than 30 cm in height, and in some cases, as high as 50 cm, but these species are exceptions.

Timing is also important in the management of coppice. Harvesting should be avoided in the period prior to the onset of the dry season or times of the year characterized by frequent frosts. By harvesting at the start of the rainy season, young coppice sprouts will have enough moisture for rapid growth. If felling is carried out during the driest period of the year, stump mortality will be higher. If stump mortality is too high, the plantation will normally have to be replanted.

Once coppice sprouts begin to develop, the plantation owner must decide whether to reduce the number of sprouts per stump, and if so, how many to retain. To obtain the largest possible sprouts – which eventually would be difficult to distinguish from the original tree – only one sprout per stump would be retained. If on the other hand, the plantation owner seeks to produce smaller products such as firewood or forage, a larger number of sprouts are managed on each stump, indeed for the smallest products no thinning whatsoever is required. When the number of sprouts is reduced, care is taken to favor the larger, more vigorous sprouts with solid attachments to the stump. Although, many plantation owners reduce the number of sprouts per stump in one operation, a number of authors indicate that shoots should be thinned in two steps, for example, a first thinning when the larger sprouts attain 3 to 4 m and a second definitive one at 7 to 8m
(Stubbings and Schonau 1980).

Stands regenerated from coppice, grow best when the sprouts develop together with direct access to full sunlight. For this reason, felling should generally be carried in blocks – cutting all trees at the same time – instead of selectively. Even with good management practices, a number of trees (stumps) will die after each felling. Eucalypt stands in Central and South America commonly produce satisfactory crops for three of four rotations. Indeed, examples of an even greater number of crops can be found cited in the literature. Ultimately, the plantation owner will have to decide whether the inevitable decline in stem number has reached unacceptable limits. In that moment, the plantation will generally be replaced.  In addition, better genetic stock is often available within one rotation, so owners that can afford to often prefer to use that sooner rather than waiting for many coppices of the same old material.

Finally, when coppice sprouts are grown in short rotations in which a large proportion of the biomass is extracted from the site, a considerable quantity of nutrients is removed over time. This exportation of nutrients will invariably lead to a reduction in site productivity. This negative outcome can be prevented by the periodic application of fertilizers to replace extracted nutrients. The amount required will vary by site, the type of fertilizer applied and the periodicity and quantity of biomass extracted.

References and Further Reading

Evans, Julian. Plantation Forestry in the Tropics: Tree Planting for Industrial, Social, Environmental, and Agroforestry Purposes. Oxford: Clarendon Press, 1992.

Jacobs, Maxwell R. Eucalypts for Planting. Rome. Food and Agriculture Organization of the United Nations (FAO), 1979.

Stubbings, J.S. and A.P.G. Schonau. “Management of Short Rotation Coppice Crops of Eucalyptus grandis Hill ex Maiden.” South African Forestry Journal. 115 (1980): 38-46.

“The Overstory Agroforestry Ejournal.”http://www.agroforestry.net/overstory/index.html (14 April 2006)

Wadsworth, Frank H. Forest Production for Tropical America. Washington: United States Department of Agriculture (USDA), 1997.

Coppice Systems V4

Posted 3 August 2006

Updated 21 April 2007