Báo cáo khoa học: "Variation of growth in Danish provenance trials with oak (Quercus robur L and Quercus petraea Mattuschka Liebl"

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article Original Variation of growth in Danish provenance trials with oak (Quercus robur L and Quercus petraea Mattuschka Liebl) JS Jensen Danish Forest and Landscape Research Institute, Lyngby Denmark 2800 Skovbrynet 16, Summary — In 1990 an evaluation was made of all 29 Danish provenance trials with oak. For the most part, north-European provenances have been used in these trials. The paper presents results from 2 provenance trials with respectively 20 and 25 provenances 25 years of age raised from seed. From these trials it can be seen that the provenances are divided into many distinctive ecotypes, and differ with regard to the time of flushing, volume yield, morphological characteristics, etc. High heritability values have been found for straightness, tree height and volume yield as well as for flush- ing, epicormics and axis formation. Q robur /Q petraea / provenance / stem form / epicormic shoot Résumé — Variabilité intraspécifique de la croissance du chêne pédonculé (Q robur L) et ses- sile (O petraea [Matt] Liebl) au Danemark. Les 29 tests de provenance de chênes installés au Da- nemark ont été étudiés en 1990. Ces tests comprenaient essentiellement des provenances d’Europe du Nord. Les résultats présentés ici concernent 2 tests regroupant 20 et 25 provenances et âgés de 25 ans. ils montrent que les provenances se répartissent en différents écotypes. Des variations im- portantes ont été observées pour le débourrement, la production en volume, la forme. Des valeurs élevées d’héritabilité ont été trouvées pour la rectitude du tronc, la hauteur, le volume, le débourre- ment, les pousses épicormiques, et la formation de la tige principale. Q robur /Q petraea / provenance/ forme du tronc / pousse épicormique INTRODUCTION often showed good form and produc- ces tion qualities, they frequently had frost die- back and mildew (Microsphaera alphi- Due to lack of sufficient seed toides). Understanding this provenance in a sources problem led to the establishment of prove- Denmark, there has always been fairly a nance trials at the beginning of this centu- large importation of acorns from different countries. Although the foreign provenan- (Helms, 1909; Hauch, 1914). ry
Cieslar (1923) described the existence 4-block designed complete experi- was as a ment, each block with 20/25 provenances. Each of different climate-conditioned oak spe- plot included 20-30 trees, 25 years of age. Both cies. He also pointed out the presumably trials were established on moist loamy-clayey high maternal inheritance for stem straight- soils which often exhibited pseudogley tenden- ness. This was strongly supported by dem- cies. onstration trials carried out by Oppermann (1932). Oppermann very carefully de- scribed the existence of various races and METHODS form types in Denmark. Later on, other ge- netic properties of oak were described by All Danish oak provenance trials were evaluated Schreiber (1952), Krahl-Urban (1959) and in 1990 and most of the trials have been meas- Kleinschmit (1977). ured several times in the past. The yield param- Due to lack of statistical knowledge, eters: height, diameter and standing volume/ha were measured, and in 3 trials the volume pro- most of the early provenance trials were duction could be quantified. The evaluations of made without replications with insufficient qualitative parameters included: stem straight- possibilities of estimating genetic gain of ness, epicormic formation, branch angle, stem phenotypic observations. axis, fork formation and flushing. Contrary to the The importance of oak for production of metric measurements of production, the estima- tion of qualitative parameters includes the use of high quality wood and as a stabilizing and a non-continuous scale. esthetic element of forests and landscapes The data were analyzed using a statistical has in recent years increased interest in software package, partly developed by the Re- the different properties of the oak races search Institute for corresponding tasks. Due to used in Denmark. the nature of qualitative values, which often In 1990, all Danish oak provenance showed a non-normal statistical distribution, trials were evaluated. In this paper, results only plotwise mean values were used for statisti- cal analyses. are presented mainly from 2 young and large trials with almost identical prove- nance compositions. Due to replications, MAJOR RESULTS FROM 2 LARGE these trials have formed a basis for esti- PROVENANCE TRIALS mating genetic gains. The major results are shown in table I. MATERIALS Concerning stem straightness, the percent- age of "acceptable" possible future trees in The 1990 evaluation included 29 provenance the stand has been estimated. In the last trials of different experimental value. Only 6 of column the average number of epicormics these trials include replicate treatments. All per tree and plot is shown. trials are randomly distributed throughout Den- The results reflect the common knowl- mark. edge in Denmark about the relationship Two of these are described here in more de- between oaks (Q robur) of Danish and tail. In 1967, 2 provenance trials were estab- lished in eastern Denmark, including 15/20 Dutch origins. The yield level is generally provenances of presumably Danish origin, 4 of higher for Dutch oak than for Danish, but Dutch origin and 1 of German origin. All of them straightness is the most important charac- are Quercus robur, except F232 which is a ter for recommending Dutch oak. The Quercus petraea of German origin. Most of the straightness of Danish oak is often very acorns for the provenance trials were collected poor. The parameter "formation of epicor- from selected stands in Denmark. Each trial
mics" is more complex; within Dutch and The effect of provenance at 25 years was Danish provenances we find provenances high, but the effect of block was reduced. producing more or fewer epicorms. In conclusion, at the age of 10-15 Provenance F232 of German origin years, it should be possible to make rough (Q petraea) showed a very high yield, its positive or negative selections. At the age straightness is moderate, and most impor- of 20-25 years, the optimum time has pre- tantly: epicormic formation is very low. This sumably been reached for deducing infor- result is surprising and has been verified in mation from these mid-sized trials. other provenance trials. correlation between the There was no and that At (nursery stage) at 2 years younger age, the trials had height an even Furthermore, there was no provided useful results. At 13 years of age, at 13 years. the differences in height and stem straight- correlation between acorn dimension and ness between provenances were statisti- the height at nursery stage. These results diverge from those reported in the litera- cally significant at a 5% level. Another im- ture, but they could be caused by less than portant parameter, the total volume optimal treatments of acorns and nursery production, showed a very low, but signifi- cant effect of provenance at 18 years of plants. However, other newly established age; however, the effect of block variation Danish trials also confirm the difficulties in predicting future growth at the nursery (site condition) was very high. At the age of 25 years, this relationship had changed. stage.
ESTIMATION OF HERITABILITY ECOTYPES AND CLINAL VARIATION OF OAK IN THE REMAINING TRIALS The 2 Danish provenance trials have Some other traits have been observed in been a powerful tool to quantify the herit- the other provenance trials. In general, ability (repeatability). The results shown provenances of Q robur imported into Den- in table II are based on the 80-100 mean mark from countries southwest of Denmark plot values from the quality evaluation flush late, and their defoliation is also late and production measurement. The values too (compared to Danish provenances). for heritability should be interpreted with Oak from Norway and Sweden flush early care and are only valid for estimations and their defoliation is also early. made under the same conditions (same Concerning the provenances of foreign location, age, treatment, provenance, origin, the length of the yearly period of etc). Heritability ranking for various char- growth and the production level seem to in- acters is probably of prime interest (Nan- crease as the latitude of the origin de- 1989). son, and vice creases versa. heritability values for The broad-sense Even though Denmark is considered a height, straightness, epicormic formation very limited area, provenances originating and flushing seem to be strongly con- from the western part (on sandy, poor soil trolled by genetic factors. The heritabilities near the North Sea) have a short period of of diameter and volume are high too, but growth compared to provenances from the these production parameters are also sen- eastern parts of Denmark. sitive to thinning strength. In harsh wind- or frost-exposed areas, have observed extreme differences in we yield and lethality corresponding to prove- nance variation. For example, Dutch and even Swedish provenances suffer from se- vere defoliation, when they are suddenly exposed to the wind. In such localities, only very distinct local ecotypes should be recommended. DISCUSSION Even if there is an evident overall clinal variation in growth, flushing, defoliation, wind-resistance etc, oak is a pioneer spe- cies. Even within limited regions, there may be deviation from the clinal variation and several ecotypes may exhibit consid- erable variation. Such factors should be taken into consideration in choosing oak provenances, whether the goals are quality of wood and/or landscape ornamental trees, for example.
The results of heritability are promising REFERENCES in relation to influencing the quantitative and qualitative genetic properties by genet- Cieslar A (1923) Untersuchungen über die ic improvement. In particular, improvement Wirtschaftliche Bedeutung der Herkunft des Saatgutes der Stieleiche. Centralbl Gesamte of stem straightness in original Danish ge- Forstwes 49, 97-148 netic materials could be important, as the Hauch LA (1914) Proveniensforsøg med eg. oak stands of Danish origin mostly have Medd Forstl Forsøgsvæs Dan 4, 295-318 very poor stem quality due to the human Helms J (1909) Et forsøg med lystræer pa Feld- devastation of forests over several hun- borg Distrikt (I). Medd Forstl Forsøgsvæs dred years. Dan 2, 297-322 The use of Q petraea in Denmark Jahn G (1988) Standorte und Waldgesellschaf- should be taken more carefully into consid- ten der Eichen (Quercus robur and Quercus eration. The phenotypic appearances, at petraea) und ihre waldbaulischen Möglich- least in younger stands, are surprisingly keiten. Ned Bosbouw Tijdschr 60, 397-402 good even on more or less clayey soils. Nanson A (1989) Genotypic and genetic param- This contrasts with earlier assumptions eters. Early testing and genotype x environ- ment interaction. In: Proc IUFRO Working where Q petraea only were recommended Party Meeting S2.02.11,Sweden 1988 (Sten- on sandy soils (Krahl-Urban, 1959; Jahn, LG, Werner M, eds), Institute for Forest er 1988). The growth of Q petraea during the Improvement, Rep no 11, Uppsala nursery stage is often much smaller than Kleinschmidt J (1977) Forstplanzenzüchtung that of Q robur and this could hypothetical- und Saatgutbereitstellung beim Laubholz. ly be a very important negative factor for Forst Holz 32, 427-433 Q petraea in the competition with different Krahl-Urban J (1959) Die Eichen. Verlag Paul weeds, at least under certain soil condi- Parey, Hamburg, 288 pp tions. Before general recommendations Oppermann A (1932) Egens træformer og racer. can be made, more investigations on older Medd Forstl Forsøgsvæs Dan 12, 400 pp stands of Q petraea should be carried out, Schreiber M (1952) Stieleichenherkunftsversuch including observations of quantitative and im Forstwirtschaftsbezirk Neuwaldegg der qualitative factors ("cracks" and "shakes" österreichischen Bundesforste, Österreich. for example). Vierteljahresschr Forstwes 93, 235-239