Báo cáo khoa học: "reproductive material of pedunculate oak (Quercus robur L) and sessile oak (Quercus petraea Matt Liebl) in France: problems and results"

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Note Forest reproductive material of pedunculate oak (Quercus robur L) and sessile oak (Quercus petraea Matt Liebl) in France: problems and results R Fernandez CEMAGREF, Genetic Improvement and Forest Nursery Laboratory, Domaine des Barres, 45290 Nogent-sur-Vernisson, France Summary — Genetic improvement of indigenous oaks (pedunculate and sessile) is only at its begin- ning but a first step has been reached with the implementation of the 1966 EC directive concerning the collection and the marketing of forest reproductive material (seed and seedlings). Two difficulties of implementation are analysed: specific purity of stands and reproductive material, and validity of the regions of provenance. A conclusion is drawn after nearly 20 years of application. Quercus robur / Quercus petraea / seed stand / region of provenance / seed / seedling Résumé — Les matériels forestiers de reproduction de chênes pédonculé et sessile en France : difficultés et résultats. L’amélioration génétique des chênes indigènes (pédonculé et ses- sile) en est à ses débuts, mais une première étape a été franchie avec la mise en application de la directive CEE de 1966 pour la récolte et la commercialisation des matériels forestiers de reproduc- tion (graines et plants) : 2 difficultés d’application sont analysées (pureté spécifique des peuple- ments et des lots de matériels forestiers de reproduction, validité des régions de provenance) et un bilan est tiré après presque 20 ans d’application de la réglementation. de provenance / Quercus robur / Quercus petraea / peuplement / région porte-graines / plants semences INTRODUCTION periority) and tested stands (superiority for 1 or several traits in comparative tests). For oaks, only the first stand type exists. In France, the genetic improvement of pe- dunculate and sessile oak is As phenotypic selection principles have just begin- ning with particular emphasis on its intra- recently been described by Fernandez (1991),this paper will focus on 2 particular specific variability. However, since 1973, aspects of the implementation of the regu- France has been applying an EC directive requiring forest seed collection in 2 types lation: specific purity and validity of the re- of stands: selected stands (phenotypic su- gions of provenance.
SPECIFIC PURITY tion started in 1973-1975. Since many mixed stands were selected then, com- plete checking is needed and will be com- Among the ’genetic’ criteria usually consid- pleted in less than 5 years from 1992. ered for seed stand selection, specific puri- ty is most important, particularly in mixed stands where natural interspecific hybridi- Seed and seedling specific purity zation is likely to occur or where it is diffi- cult to discriminate between species. Moreover, the regulation is very strict and A seed discrimination method can be ap- imposes more than 99% purity in seedlots plied with 85% confidence (Dupouey and and seedlings. This implies that methods Le Bouler, 1989) but, as it requires 2 are necessary to identify oaks species measurements/acorn, it is difficult to use when stands are selected and to control widely. Seedlings can easily be identified, seedlot and seedling purity, from collection but only when in leaf. Therefore, checking to planting. stand purity before selection is of the ut- most importance. Specific purity at the stand level VALIDITY OF REGIONS OF PROVENANCE It has recently been demonstrated that ar- tificial hybridization of sessile and pedun- culate oak is possible, but that intermedi- A of provenance has double region a no- ate forms are rare in nature (Badeau, tion; it reflects biological (ecotypes, ecolo- 1990). Morphological identification is easy gy) and practical factors (seed and seed- (Dupouey, 1983; Sigaud, 1984; Badeau, lings). 1990). Biochemical identification is possi- Although applied with some differences ble (Zanetto, 1989) but, since no enzymat- in the different EC countries (Fernandez, ic system discriminates between the spe- 1991),the definition is based on broad cli- cies, allele frequency has to be matic and geological classes. A narrower considered. Unfortunately, biochemical classification based on ecotypes or pheno- identification is not yet applicable in rou- types appears impossible in practice. In or- tine tests and does not reveal intermediate der to avoid seed and seedling transfer be- forms. tween ecologically different zones, a large Therefore synthetic criteria such as number of regions have been isolated: 10 architecture and foliage organiza- for pedunculate oak and 15 for sessile oak. crown tion have to be used. Until their reliability is Unfortunately, the validity of these re- proven more accurately, they are provi- gions has not yet been evaluated. Iso- sionally applied in different geographical zymes only partly solve the question. So and ecological conditions with great care. far, France has been divided into 4 main Mixed stands are rejected when they units, some of them being contradictory in contain more than 5% undesirable trees terms of sessile oakregions of provenance belonging to the less represented species (Zanetto, 1989). This preliminary result in or intermediate forms. Undesirable trees in based on a sample of only 30 stands, selected stands are thinned out. Unfortu- while regions of provenance altogether nately, and because of urgency, these represent 130 stands. Furthermore, iso- as rules were not applied when stand selec- are considered neutral, they cannot zymes
The main limitation to the application of reflect ecotypic diversity. Non-neutral genet- the EC regulations is that they are only ic markers, like DNA, may provide a more concerned with seed collection and the precise discrimination. For the time being, it seed and seedling trades. Use of genetic appears that genetic diversity can only be material in reforestation is uncontrolled but assessed through a multiple site prove- foresters receive advice from CEMAGREF, nance network which will clarify the homo- the government body in charge of stand geneity of the regions of provenance; these selection, thanks to its new version of the findings will lead to the upgrading of some handbook on forest reproductive material selected stands in the tested category. (CEMAGREF, 1991b). RESULTS CONCLUSION Twenty years of application of the EC reg- If after 20 years, people have become ulation has resulted in several positive as- used to the EC regulations, several as- pects. 4,000 of the 2.1 million hectares of pects still need to be amended so as to pedunculate oak and 11,000 of the 1.6 mil- make their application more certain, espe- lion hectares of sessile oak have been se- cially the control of synthetic morphologi- lected. These stands are grouped into re- cal markers, and the development of a gions of provenance and are listed in the technique that could cheaply and reliably national forest basic material inventory identify the species of acorns. (CEMAGREF, 1991 a). Control of the integrity of provenance re- Since 1989, all seed collection has gions should lead to success but one must entirely from selected stands, except come keep in mind that this notion - which is pri- when acorn production is particularly marily a pragmatic one - aims at avoiding scarce (table I). Nationally, the annual re- both unwise genetic transfers and conse- quirement for seedlings represents 4.5 mil- quent enormous adaptation mistakes. The lion pedunculate oak seedlings and 6.8 cost of the necessary research should not million sessile oak seedlings. These are exceed the possible benefits to be essentially covered by French collections. of achieved through the implementation Imports are limited while exports of sessile the EC regulation. oak to other EC countries are important.
Dupouey JL (1983) Analyse multivariable de REFERENCES quelques caractères morphologiques de po- pulations de chênes (Quercus robur L et (1990) Étude de la variabilité morpho- Badeau V Quercus petraea (Matt) Liebl) du Hurepoix. des chênes en Lorraine. DEA, The- logique Ann Sci For 40, 265-282 Université de Nancy I et INRA sis, Dupouey JL, Le Bouler H (1989) Discrimination CEMAGREF (1988, 1989, 1990, 1991, 1992) morphologique des glands de chênes ses- Récoltes et flux de graines, campagnes sile (Quercus petraea (Matt) Liebl) et pédon- 1986/1987 à 1990/1991. Division améliora- culé (Quercus robur L). Ann Sci For 46, tion génétique et pépinières forestières, No- 167-194 gent-sur-Vernisson Fernandez R (1991) Selected forest reproduc- CEMAGREF (1991a) Répertoire National des tive material in France: critical analysis and Matériels de Base Français des Essences results. Meeting of the IUFRO working party Forestières. 3rd ed. Division amélioration S2.02.21, Gmunden and Vienna, pp 8 pépinières forestières, Nogent- génétique et Sigaud P (1984) Les chênes du Berry. ENITEF sur-Vernisson, pp 106 thesis, Nogent-sur-Vernisson Amélioration des Essenc- CEMAGREF (1991 b) Zanetto A (1989) Polymorphisme enzymatique Forestières, Matériels Contrôlés et Sélec- es du chêne sessile. DEA, Thesis, INRA Bor- tionnés : Conseils d’Utilisation. Ministère de l’Agriculture et de la Forêt, pp 90 deaux