Báo cáo khoa học: "Performance of different provenances and of the local population of the Monterey pine (Pinus radiata D Don) in northern Spain"

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Note Performance of different provenances and of the local population of the Monterey pine (Pinus radiata D Don) in northern Spain S E Ritter Espinel, A Aragonés CIMA, Apartado 46, 01080 Vitoria-Gasteiz, Spain 22 13 (Received February 1994; accepted April 1995) Summary — The performances of 3 Pinus radiata provenances, composed of different subprove- nances, and of the local population were compared in a completely randomized design in a 4-year trial at Onyi Mountain (Basque country, northern Spain). Significant differences between populations were observed for the growth characteristics. The Monterey population showed the best performance, although a considerable degree of variation among subprovenances was present. Unfavorable cli- matical conditions in the winter of 1992/1993 caused high mortality rates in the provenances of Mon- terey and Cambria, while the Año Nuevo population and the local population were less affected. Based on the comparison of growth characteristics, mortality and morphological characters, Año Nuevo seems to be the possible origin of the local Basque population. Pinus radiata / provenance / performance / morphological character / frost resistance Résumé — Performances comparées de différentes provenances de Pinus radiata D Don et d’une population locale au nord de l’Espagne. Les performances de 3 provenances de Pinus radi- ata composées par différents sub-provenances ont été comparées avec une population locale à la mon- tagne d’Onyi (Pays Basque, nord de l’Espagne) dans un essai randomisé pendant 4 ans. On a trouvé des différences significatives pour les caractéristiques de croissance entre les populations étudiées. La population Monterey a montré les meilleures performances malgré les variations entre sub-prove- nances. Les mauvaises conditions climatiques pendant l’hiver 1992/1993 ont été la cause de la mor- talité élevée des populations Monterey et Cambria, tandis que les populations Año Nuevo et locale ont été moins affectées. Sur la base de la comparaison de croissance, mortalité et caractéristiques mor- phologiques, l’origine de la population locale basque peut être la population Año Nuevo. Pinus radiata / provenance / comportement / caractéristique morphologique / résistance au froid
INTRODUCTION total of 560 2.5 2.5 seedlings (initial spacing mx m). The heights of all the trees in this trial were Before introducing tree species into a spe- determined annually. The 1 st measurement was cific new environment or at the beginning taken in October 1990 (H1), the 2nd at the end of of local breeding programs, provenance September 1991 (H2), the 3rd in October 1992 tests are quite common to determine their (H3) and the 4th in October 1993 (H4), so that potential value (Shelbourne et al, 1979; these measurements represent the heights of 1-, 2,- 3- and 4-year-old trees in the field, res- Eldridge, 1983; Zobel and Talbert, 1984; pectively. Annual growth increments were com- Burdon et al, 1992a). puted for each period as differences between the The Monterey pine (Pinus radiata D Don) corresponding annual heights. is the tree species of greatest economic In winter 1992/1993, severe cold and remar- interest in the Basque country in northern kable temperature variations occurred and 143 Spain (162.000 ha). This species was first of the young trees died. In February 1993 in par- introduced at the end of the last century fol- ticular, the temperature decreased from 17 to -7.5°C within 8 days. The mortality was recor- lowed by a second introduction in the 1920s. ded for each subpopulation in June 1993. Some A breeding program for this species has morphological needle characters were measured been established recently and one of the in 10 random samples of entire fascicles of mature first steps of this program consisted of com- needles from 5 different trees of each subprove- paring the growth and morphological cha- nance and of the local population collected in racteristics of the local population and that of autumn 1992. Traits recorded for the needle fas- cicles were needle length and total number of the natural populations from California, the stomata on a 5 mm long section in the middle of natural occurrence of Pinus radiata. the needle (Eguiluz, 1984). In addition, the weight of 100 seeds and the cotyledon number of the seedlings were determined. MATERIALS AND METHODS Statistical analyses were performed with the SAS program package. Specifically, PROC GLM was used taking into account only the popula- The plant material used in this field trial consisted of seed samples from 3 provenances (Año Nuevo, tion effect in the model for analyses of variance and Fisher’s LSD test for the comparison of PI; Monterey, PII; Cambria, PIII) of the natural populations from California (Eldridge, 1983; Moran means. et al, 1988) and of a bulked seed sample from the Basque population (PB). This population represents a homogenous one since cones from RESULTS many locations are collected, dried at one main point and the seeds then redistributed again. The 3 populations of California were composed of Highly significant population effects were several subprovenances formed by stands based found for each annual height in the analysis on ecological and environmental criteria as defi- of variance. Table la shows the average ned by Eldridge (1983) and following the same annual heights of the trees of each popula- nomenclature. Provenance I, II and III consisted tion and subpopulation. Provenance II show- of 4, 6 and 3 subprovenances, respectively. Seed material from these natural populations was obtai- ed the highest average tree heights in every ned from the CSIRO Collection (1978). year, which differed significantly from all the One hundred seeds of each subprovenance others in the first 2 years. The lowest ave- and of the local population were sown in contai- rage heights were always recorded for Pro- ners in the greenhouse in February 1989. In May venance I, which were significantly lower in 1990, uniform seedlings of the 14 populations the 3rd and 4th year. The heights of the were planted in a completely randomized design local population PB always fell between with 5 tree plots and 8 repetitions at Onyi Moun- those of PII and PIII. These tendencies were tain (Guipuzcoa, northern Spain) leading to a
DISCUSSION also visible on the level of subpopulations with respect to the maximum values, although a considerable degree of variation Significant differences were found for growth between the average annual heights within characteristics, as well as for some mor- the subpopulations of each population was phological characters, between the different present. Subpopulation II/1 showed a remar- Pinus radiata provenances and the local kably poor performance throughout all of in our trial. Performances of the population the years with respect to the other subpop- provenances have also been compared in ulations of Provenance II. different trials in other countries, showing a Table Ib shows the average annual considerable degree of variability in the ran- growth increments for each year and each king. As in our trial, ProvenanceI (Año population and subpopulation. Provenance Nuevo) showed the lowest growth in New I always had the lowest growth increments. Zealand (Burdon et al, 1992b). While the Provenance II showed the highest ones only Monterey population also had the highest in the vegetative period 1991/1992, but growth in South Africa (Falkenhagen, 1991), would have always had the highest incre- the Cambria population outgrew all other ments if the unfavorable subpopulation II/1 provenances in New Zealand. had been excluded. The local population Bourdon et al (1992b) stated that the Año showed intermediate growth increments be- Nuevo provenance seemed to be more tween those of PI and those of other popu- resistant to cold than the Monterey one, and lations, depending on the year. The growth that the Cambria population was the most increments in the period 1992/1993 were sensitive, which is consistent with our results. generally much lower than in the other per- Apparently, the mortality in the natural popu- iods, since the climatical conditions were lations corresponds to their geographical unfavorable. descendance. The observed mortalities in 1992/1993 The origin of the early introductions into presented for each population and sub- are the Basque country could not be determi- population in table Ic. The significantly ned. A possible relation of the local popula- highest mortalities of over 50% were obser- tion with Provenance II from Monterey can ved for the population PIII followed by PII be discarded when comparing growth cha- with nearly 30%. Provenance I and the local racteristics and morphological characters population PB were considerably less affec- between these 2 populations. With respect ted by these climatical conditions and show- to the annual heights, the local population ed no significant differences in mortality. occupied an intermediate position between However, the local population had the lowest those of ProvenanceI and Provenance III mortality with only 2.8%. The average values with an apparently closer relationship to of the morphological needle characters, of population PIII. However, when comparing the seed weights and of the cotyledon num- the mortalities in these populations, it seems bers are presented in table II. Significant evident that the local population descends differences between populations were found from the Año Nuevo population (PI). A pos- for all traits. The highest average values for sible adaptation process can be excluded the needle length and the stomata number in this case for the following reason: unfa- were found for population P1 and the local vorable conditions like those of the winter population of the Basque country. The Mon- 1992/1993 have occurred frequently in the terey population had the significantly lowest past. If such high mortalities as observed in seed weight and the lowest average number the PIII population had occurred, it seems of unlikely that this provenance could have cotyledons.
after introduction. Since the present study become established in the Basque country. is limited by the age of the trees and by the Instead, the improved growth of the local lack of different trial sites, further studies population with respect to PI can be explain- are necessary to ensure the obtained ed by an adaptative process, since seeds for reforestation were taken from well-per- results. forming trees adapted to the particular cli- matological conditions of this region. REFERENCES The hypothesis that the local population descends from Año Nuevo is also supported by the similarities among PI and PB with Burdon RD, Bannister MH, Madgwick HAI, Low CB important morphological to (1992a) Genetic survey of Pinus radiata. 1. Intro- respect some duction, description of experiment, and basic metho- characters (table II). Needle length, stomata dology. NZ J For Sci 22, 119-137 numbers and cotyledon numbers of the local Burdon RD, Bannister MH, Low CB (1992b) Genetic population resemble those of PI more than survey of Pinus radiata. 2. Population comparisons those of PIII. The increased seed weight of for growth rate, disease resistance, and morpho- the local population, which shows a closer logy. NZ J For Sci 22, 138-159 relationship with the Cambria population, PT (1984) Geographic variation in needles, Eguiluz and seeds of Pinus tecunumanii in Guate- cones probably results from a selection process mala. Silvae Genetica 33, 72-79 towards bigger seeds within the local popu- KG (1983) Genetic resources available. In: Eldridge lation. Radiata pine breeding manual (AC Matheson, AG Excluding the somewhat outstanding Brown, eds), Division of Forest Research, CSIRO, Camberra, 3.1-3.15 subpopulation II/1, the superior growth cha- in Pinus Falkenhagen ER (1991) Provenance variation racteristics of the Monterey population under radiata at’6 sites in South Africa. Silvae Genetica evident. environmental conditions are our 40, 41-50 Therefore, it would be beneficial to intro- Moran GF, Bell JC, Eldridge KG (1988) The genetic duce plant material of this provenance to structure and the conservation of the 5 natural popu- achieve increased selection success in the lations of Pinus radiata. Can J For Res 18, 506- 514 local breeding program. The relatively high Shelbourne CSA, Burdon RD, Bannister MH, Thulin IJ mortality rates also observed in this prove- (1979) Choosing the best provenances of radiata nance and the considerable amount of varia- pine for forest sites in New Zealand. NZJFor Sci tion among subprovenances imply a careful 24, 288-300 selection of the ecological stand to be intro- Zobel B, Talbert J (1984) Applied forest tree improve- duced and an intensive selection process ment. John Wiley & Sons, New York