The Field Manual on “Mass Vegetative Propagation of Dipterocarps”, written by my colleague, Dr. N. Q. Zabala, Tree Propagation Specialist, is the first in the series of Field Manuals to be published by our project to provide guidance to field workers and researchers working in the field of tree breeding and plant propagation.
Vegetative propagation, especially propagation through stem cuttings, has gained much prominence in forestry during recent times. It has been used with remarkable success in the establishment of clonal gardens, clonal seed orchards and in the establishment of clonal plantations, especially of Acacias, Casuarinas, Dipterocarps and Eucalypts.
The Field Manual is based on first-hand information Dr. Zabala gathered during his visits to Indonesia and Malaysia and also meeting with scientists working in the field of clonal propagation. We hope our readers will find the methods described here useful.
Dr. K. Vivekanandan
Chief Technical Adviser
and
Project Coordinator
Los, Baños, Philippines
May, 1993
Dipterocarps species constitute about 70% of the commercial stock in the tropical forest of South Asia, which used to be the mainstay of the timber industry in the region. Dipterocarp wood made up 25% of the world trade in hardwood until the end of the logging boom in the 1970s, and now the fragile ecosystem of the dipterocarp forest has been disturbed and their very existence has been threatened. It is of extreme urgency, therefore, to adopt sustainable measures to conserve, restore and enrich the dipterocarp forest to make it more viable for economic and ecological considerations.
Dipterocarps are locally adapted and few species of insects and diseases are known to affect them. Their use in reforestation is reasonably justified because they already have taken an important place in the domestic and world trade in hardwood.
There are, however, some problems in the production of planting stock of dipterocarps by seeds, such as irregularity of seed supply due to irregular flowering and fruiting (seed year phenomenon), short viability period of seeds and lack of seed storage and handling facilities which have hampered restoration and enrichment activity for the regeneration of the dipterocarp forest. To solve these problems, collection of wildlings has been resorted to, but dependency on such supplies could not be sustained due to erratic seed years, the difficulty of collecting them in the forest and the laborious hardening process encountered. Beset with these drawbacks in the production of sexually propagated planting materials, efforts have been directed towards mass production of asexual planting stocks through rooted cuttings. One of the advantages of asexual propagation is that cuttings retain the genetic characteristics of the selected donor trees which could bring about considerable gains in terms of volume production, uniformity in wood quality and growth and rapid return to investment. Its major disadvantages, however, are higher cost of investments and greater biological risks from parasites, diseases, and climatic hazards due to a drastic and deliberate reduction of genetic variability of production plantations. Clonal forestry would then be relevant (1) when high performing individuals, proven as such through careful screening and evaluation in field tests are available; (2) when there is sufficient number of superior clones which can be mass propagated in equal numbers of each clone in order to maintain a “variation in space”, new, possibly partly overlapping sets of clones, must be used each year; and (3) when more productive and more resistant clones are continuously injected into the planting programmes, through continuous genetic improvement programmes in order to maintain “variation in time”.
Success in rooting cuttings could be achieved by (a) using juvenile stock, i.e., one to two-year old seedlings or 45–60 day old coppice shoots from less than six-years old plants (depending on the species); (b) maintaining relative humidity at about 80% or above and temperature at about 23°C to 28°C inside the rooting chamber; (c) providing good aeration in the propagation shed; and (d) using the most effective rooting medium and rooting hormone at suitable concentration levels. Because of the great potential of clonal forestry for increasing wood production and enhancing ecological stabilization, concerted efforts of R & D agencies have been devoted to the mass production of vegetative planting stock by rooting cuttings. Progress made on this aspect, with special reference to the dipterocarps, is presented in this practical guide. The methods and materials used by different researchers are described in detail to give the intended user a comprehensive idea of how the method(s) could be applied and replicated.
