A reciprocal transplant trial suggests a disadvantage of northward seed transfer in survival and growth of Japanese red pine (Pinus densiflora) trees
Teruyoshi Nagamitsu & Ken-ichi Shimada & Ayako Kanazashi
Received: 4 August 2014 /Revised: 19 October 2014 /Accepted: 29 October 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Seed transfer regulation in forest trees is to prevent the plantation of maladapted trees in non-local sites. Seed transfer from southern to northern Japan is prohibited in
Japanese red pine (Pinus densiflora). To evaluate the current regulation of seed transfer, a reciprocal transplant trial was conducted in P. densiflora trees originating from two provenances in southern (S) and northern (N) Japan and planted in sites S andN near these provenances.We observed survival rate at 0–15 years old before a thinning and at 15–30 and 15– 40 years old after the thinning and measured diameter, perplanted-area cross-sectional area, and shape of stems of 30year-old trees. The survival rate before the thinning was lower in provenance S than in provenance N and in site S than in site
N. The survival rates after the thinning were lower in non-home sites, in particular, provenance S in site N. The stem diameter was largest in provenance S in site S, smallest in the both provenances in site N, and intermediate in provenance N in site
S. Thus, trees were fewer and larger in provenance S than in provenance N in their home sites. As a result, the per-plantedarea stem cross-sectional area of 30-year-old trees was smallest in provenance S in site N, suggesting a disadvantage of northward transplantation. Proportions of trees with broken and/or crooked stems were higher in site N than in site S, suggesting that a northern environment is more stressful. These findings support the current regulation of seed transfer directions in
Japanese P. densiflora.
Keywords Local adaptation . Provenance . Seed transfer .
Stem productivity . Stem diameter . Survival rate
Many forest tree species have genetic variations in various traits across geographical scales (White et al. 2007). These species in spatially heterogeneous environments often show local adaptation (Leimu and Fischer 2008), which is also referred to as a home-site advantage (O’Brien and Krauss 2010). In forest trees, survival, growth, phenology, and resistance to biotic and abiotic stresses are expected to adapt locally (Savolainen et al. 2007). The fitness advantage in home sites leads to divergent natural selection and results in a geographical variation in a trait adapted to the local environments, whereas gene flow can diminish it (Kawecki and Ebert 2004). Although forest trees have a wide spatial range of gene flow, the pressure of the divergent natural selection seems to be sufficiently strong because of the high mortality from seedlings to adults, the long life span, and the sessile life form in forest trees (Petit and
Hampe 2006; Kremer et al. 2012).
With regard to the local adaptation of forest trees, the importance of utilization of local seeds has been widely recognized in reforestation (McKay et al. 2005; Breed et al. 2012). Breeding zones and seed transfer regulation are practical tools to minimize the risk of maladaptation in reforestation (Ying and Yanchuk 2006; Salmela et al. 2010). In Japan,
Communicated by J. Beaulieu
Electronic supplementary material The online version of this article (doi:10.1007/s11295-014-0813-2) contains supplementary material, which is available to authorized users.
T. Nagamitsu (*) :K.<i. Shimada
Department of Forest Genetics, Forestry and Forest Products
Research Institute (FFPRI), 1 Matsunosato, Tsukuba,
Ibaraki 3058687, Japan e-mail: firstname.lastname@example.org
K.<i. Shimada e-mail: email@example.com
Hokkaido Research Station, Forestry and Forest
Products Research Institute, 7 Hitsujigaoka, Toyohira-ku,
Sapporo, Hokkaido 0628516, Japan e-mail: firstname.lastname@example.org
Tree Genetics & Genomes (2015) 11:813
DOI 10.1007/s11295-014-0813-2 seed transfer in four conifer species, which are important in wood production and forest management, is legally controlled by the Forestry Seeds and Seedlings Act established in 1939.
This legal regulation assumes local adaptation in these species. Therefore, the assumption of local adaptation should be tested in each species empirically to justify the seed transfer regulation in spite of its economic cost.
A common-garden experiment with multiple provenances in multiple plantation sites is an effective method to verify a genetic variation among the provenances and a home-site advantage in each site (Rehfeldt et al. 1999). An appropriate experimental design, in which the factors of site and provenance cross each other with replications, statistically discriminates the genetic and environmental variations as well as their interactions, which indicate the home-site advantage (Bennington et al. 2012). Such experiments are often called provenance trials in forest tree breeding (Ying and Yanchuk 2006; Salmela et al. 2010). There is a long history of provenance trials, which can be used retrospectively to investigate adaptive traits and fitness components in the late stages in a life cycle of forest trees (Aitken et al. 2008). In Japan, however, provenance trials in a geographic scale covering the whole distributional range have rarely been conducted, even in important forest tree species (Nagamitsu et al. 2013).
The Japanese red pine (Pinus densiflora Sieb. et Zucc.,
Pinaceae) is a conifer species in semi-mountainous forests and is important both economically and culturally. This species is one of the four species regulated by the Forestry Seeds and
Seedlings Act in Japan. Seed transfer zones are divided into three areas (northern, southeastern, and southwestern zones), and seed transfer from the southern two zones to the northern zone and from the southeastern zone to the southwestern zone is prohibited (Fig. 1a). A remarkable decline in populations of the Japanese pines (P. densiflora and P. thunbergii Parl.) occurred, particularly in southwestern Japan, during the past 50 years due to the pine wood nematode (Bursaphelenchus xylophilus) introduced from North America (Mamiya 1988).