Technical Note No. 14 (May 1984) from the DANIDA Forest Seed Centre deals with the establishment and management of Provenance Seed Stands and Provenance Conservation Stands. It includes sections on Definitions, Establishment, Thinning and Records; and appendices on Selection of plus trees, Plot methods of tree selection and thinning, Guidelines for a systematic thinning regime and Recording forms for Provenance Seed Stands and Provenance Conservation Stands.
Provisional estimates are given, for a few common tropical plantations species, of the seed production which may be expected in good seed years from mature Provenance Seed Stands. This is intended as a guide to those planning tree improvement programmes, so that they can relate the area of any seed stand being established to the future annual planting area for which that seed stand will be expected to supply seed. The table is reproduced here, but it is emphasized that these are rough average figures which in practice will vary considerably from provenance to provenance, from site to site and from year to year.
| Seed production per ha of seed stand in good seed years & at full production age | Clean seeds (or fruits) per kg | Plant % | Plantable plants per ha of seed stand | Area of plantations established in 1 year from 1 ha of seed stand (+ (ha) | |
Pinus caribaea var. hondurenses | 15 | 60,000 | 45 | 405,000 | 300 |
| P. oocarpa | 7.5 | 58,000 | 48 | 209,000 | 155 |
| P. kesiya | 15 | 50,000 | 42 | 315,000 | 233 |
| P. merkusii (Thailand) | 7.5 | 30,000 | 42 | 95,000 | 70 |
| P. patula | 15 | 125,000 | 36 | 675,000 | 500 |
| Gmelina arborea | 300 | 1,600 | 50 | 240,000 | 178 |
| Tectona grandis | 200 | 2,000 | 10 | 40,000 | 30 |
A minimum size of 5–10 ha is recommended for both Seed Stands and Conservation Stands, with isolation strips of at least 330 m between the stands and any potentially hybridizing neighbouring stands. The strips may conveniently be planted with a non-hybridizing species which will provide a partial physical barrier against immigration of foreign pollen.
Guidelines to thinning of stands includes cases where a systematic thinning regime, which aims to conserve as far as possible the original variation in the stand, is combined with the retention of up to a maximum of 10 superior phenotypes per ha which could be of great value to a future breeding programme. This compromise between management to favour phenotypic superiority and management to conserve maximum phenotypic diversity is likely to be an appropriate method of managing conservation stands during the early stages of an introduction and improvement programme.
(The Technical Note in full (41 pages), is available from the DANIDA Forest Seed Centre, Krogerupvej 3A, DK 3050 Humlebaek, Denmark (English only)).
