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Single-tree management for high-value timber species in a cool-temperate mixed forest in northern Japan

Single-tree management for high-value timber species in a cool-temperate mixed forest in northern... INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT, 2016 VOL. 12, NOS. 1–2, 74–82 http://dx.doi.org/10.1080/21513732.2016.1163734 Special Issue: Synergies between biodiversity and timber management Single-tree management for high-value timber species in a cool-temperate mixed forest in northern Japan a a a a b Toshiaki Owari , Koji Okamura , Kenji Fukushi , Hisatomi Kasahara and Shinichi Tatsumi The University of Tokyo Hokkaido Forest, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Furano, Japan; Division of Natural Environment and Information Research, Graduate School of Environmental and Information Science, Yokohama National University, Yokohama, Japan ABSTRACT ARTICLE HISTORY Received 30 April 2015 High-value hardwood species such as monarch birch (Betula maximowicziana) and castor Accepted 6 March 2016 aralia (Kalopanax septemlobus) are important economic and ecological elements of cool- temperate mixed forests in northern Japan. This article presents the single-tree management EDITED BY system for high-value timber species as practised for 50 years at the University of Tokyo Nicholas Brokaw Hokkaido Forest. Nearly 2000 valuable broad-leaved trees meeting the size and quality criteria KEYWORDS have been registered as ‘superior trees’, and their status is periodically monitored for timing Auction market; fancy wood; of harvest. A case study was conducted using 2105 inventory plots to characterize the stand high-value tree species; types in which superior trees occur. A total of 57 superior trees of 11 broad-leaved species single-tree registry system; was found in 2.2% of the inventory plots. The results indicated that superior trees generally superior tree; The University grew in mature species-rich stands. Superior trees of some species may have promoted their of Tokyo Hokkaido Forest abundance by dispersing relatively more seeds to the surroundings. Single-tree management facilitates the sustainable use of high-value timber species by explicitly monitoring the numbers, attributes and locations of superior trees, and contributes to conserving stand structural diversity through protection of these large-sized canopy trees, which promotes ecological values such as biomass and carbon storage, species diversity, seed abundance and bird habitat. The production of fancy wood from superior trees earns significant income –3 through extremely high log prices (maximum > 20,000 USD m ). forest ecosystems (Lindenmayer et al. 2012), with Introduction regard to biomass, carbon storage (Lutz et al. 2012; High-value timber species are those used for products Sist et al. 2014; Kauppi et al. 2015) and structural with extremely high commercial value. The monarch heterogeneity (Lutz et al. 2013). Their social and birch (Betula maximowicziana Regel) and castor ara- cultural values are also significant (Blicharska & lia (Kalopanax septemlobus (Thunb.) Koidz) are the Mikusiński 2014). Management of valuable large old most valuable timber species of cool-temperate mixed trees may help conserve both the economic value and forests in northern Japan, fetching log prices of up to the biodiversity of the forests they inhabit. –3 20,000 USD m . Other high-value species include Due to their economic value, high-value timber big-leaf mahogany (Swietenia macrophylla King) and species are often intensively harvested with little ipê (Tabebuia spp.) in Latin America (Kometter et al. attention to the impacts on their population struc- 2004; Grogan et al. 2010), African mahogany tures and dynamics (Schulze et al. 2008). They suffer (Entandrophragma spp.) in Africa (Romeiras et al. from illegal logging (Ward et al. 2008) and are 2014) and rosewood (Dalbergia cochinchinensis becoming increasingly scarce in heavily logged forests Pierre) in Southeast Asia (So et al. 2010). In Europe, (Prates-Clark et al. 2008). The most valuable timber valuable broad-leaved genera (Acer, Alnus, Betula, species are often the most threatened ones (So et al. Fraxinus, Juglans, Prunus, Sorbus, Tilia and Ulmus 2010). Thus, fundamental changes in forest manage- spp.) produce high-value timber that is used in the ment practices are urgently needed to conserve exist- veneer and furniture industries (Hemery et al. 2008; ing trees of high-value timber species, as well as forest Oosterbaan et al. 2009). biomass and structural heterogeneity. Lindenmayer Even though high-value timber species typically et al. (2014) suggested creating a tree registry system occur at very low densities (Schulze et al. 2008), that aims at promoting their protection. He suggested they play important economic and ecological roles that single-tree management of valuable tree indivi- in forest management (Oosterbaan et al. 2009). duals should replace unplanned harvests by explicitly Trees with high economic value are often large and identifying tree attributes and locations in forests. old. Large old trees are key structural attributes in CONTACT Toshiaki Owari owari@uf.a.u-tokyo.ac.jp The University of Tokyo Hokkaido Forest, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 9-61 Yamabe-Higashimachi, Furano 079-1563, Japan © 2016 Informa UK Limited, trading as Taylor & Francis Group INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 75 In this article, we describe single-tree management from a large area (Zingg 1999). The cutting cycle is either 15 or 20 years, depending upon stand growth of high-value timber species in a cool-temperate mixed forest in northern Japan. A case study was rates and accessibility. In each managed area, the rate conducted at the University of Tokyo (UTokyo) of tree removal is 10–17% of the growing stock per cutting cycle, which is lower than the stock growth Hokkaido Forest, where single-tree management for high-value hardwoods has been practised since the rate (The University of Tokyo Hokkaido Forest 2012). Logging operations typically use felling with mid-1960s, and nearly 2000 trees with superior tim- chainsaws and skidding of the felled stems by a ber quality have been registered as ‘superior trees’ and monitored on an individual-tree basis. Our spe- winch-equipped crawler tractor (Tatsumi et al. 2014). The mean annual tree removal and timber cific objectives were (1) to identify how stands in sales (stumpage and logs) during 2006–2010 were which superior trees occur differ from stands without such trees, in terms of tree density, basal area (BA) 23,100 m and 120 million Japanese Yen (JPY) and species richness and (2) based on differences (approximately 1 million USD), respectively (The between stands with and without superior trees, to University of Tokyo Hokkaido Forest 2012). consider how single-tree management for superior trees might help to conserve forest biodiversity. We Single-tree management for ‘superior trees’ also present the economic benefits of single-tree management for high-value trees. To maintain and sustainably produce high-value tim- ber in managed stands, the UTokyo Hokkaido Forest has been practicing the single-tree management sys- Methods tem since 1965 (Shibata 1988; Yamamoto et al. 1989; Yamamoto 1990). The system has three components: UTokyo Hokkaido Forest and management (1) single-tree selection and registration, (2) measure- policies ment and assessment and (3) periodic monitoring for The UTokyo Hokkaido Forest was established in 1899, optimal harvest. when national forests were transferred from the Under the single-tree management system, large- Ministry of Home Affairs to the UTokyo. It is located sized canopy trees with high timber quality and value in the centre of Hokkaido Island, in northernmost have been individually selected and registered as Japan (43°10′–20′ N, 142°18′–40′ E, 190–1459 m asl), ‘superior trees’ (The Tokyo University Forest in and has an area of 22,716 ha. The mean annual tem- Hokkaido 2012). Operational guidelines for selecting perature and precipitation at the arboretum of the superior trees include diameter at breast height (DBH Forest (230 m asl) during 2001‒2008 were 6.3°C and ≥ 40 cm), crown height (≥4 m) and estimated length 1210 mm, respectively (The University of Tokyo of butt log (≥4 m) (The University of Tokyo Hokkaido Forest 2012). Snow (maximum 83 cm in Hokkaido Forest 2012). There are also qualitative depth) usually covers the ground from late criteria for single-tree selection: the trunk should be November to early April. The typical substrate and straight, the cross section should be a circle and the soil type are welded tuff and dark-brown forest soil. stem should have few defects such as bending, twist- The Forest is situated in the pan-mixed forest zone ing, knots from branches or dormant buds, and (Tatewaki 1958), which is transitional between decid- decay. uous forests in the cool-temperate zone and coniferous All superior trees are numbered, and DBH, species forests in the Sub-Boreal zone. Uneven-aged mixed name, tree vitality (based on visual assessment of tree forests with coniferous and broad-leaved tree species crown) and stem damage (if any) are recorded. The are the main vegetation cover. As of 2011, the total geographic locations have been partly obtained using –1 and mean ha growing stock of the Forest were 4.8 a global navigation satellite system (GNSS) receiver 3 3 –1 million m and 211 m ha ,respectively (The with positional accuracy < 5 m (Owari et al. 2011; University of Tokyo Hokkaido Forest 2012). Tokuni et al. 2016). As shown in Figure 1, registered A large-scale and long-term experiment on the superior trees are sparsely distributed over the man- stand-based silvicultural management system agement area. This precise information on individual (Takahashi 1961; Watanabe & Sasaki 1994) has been tree positions is, therefore, crucial for single-tree conducted at the UTokyo Hokkaido Forest since management practices. The status of registered super- 1958. The idea behind the system is that management ior trees is periodically monitored by tree-marking should be adapted to the conditions of each stand to crews for harvest at the optimal time (see below). maximize the multiple public and economic func- A total of 1952 superior trees from 19 valuable tions of forest ecosystems (Takahashi 2001). Single- broad-leaved species was listed on the registry as of tree selection harvest has been implemented as the September 2014. Major species in the registry and main silvicultural system at the Forest, in which trees included in this study were K. septemlobus (Thunb.) are periodically selected and harvested individually Koidz, Quercus crispula Blume, Tilia japonica (Miq.) 76 T. OWARI ET AL. Figure 1. An example of location map for registered superior trees (Compartment no. 56) at the University of Tokyo Hokkaido Forest. Simonk., B. maximowicziana Regel and Fraxinus the plot size was normally 0.25 ha (50 m × 50 m). The mandshurica Rupr. (Figure 2). Their mean DBH species and DBH classes (2 cm intervals) for all live was 64.3 cm, with a range of 40–110 cm. Shibano trees with DBH ≥ 5 cm were recorded in each plot. et al. (1995) found that superior B. maximowicziana We determined whether registered superior trees trees that had been harvested during 1988–1993 ran- occurred in each plot from the measurement record. ged between 105 and 316 years in age and 48–108 cm For this study, we focused on T. japonica, K. septem- lobus, F. mandshurica, B. maximowicziana and Q. in DBH. According to the 10-year forest management plan crispula. for 2011–2020, 100 m of superior trees are to be To characterize the stands where superior trees of these five species occur and that are under single-tree harvested annually (The University of Tokyo management, tree density (number of tree individuals Hokkaido Forest 2012). Superior trees are harvested on the basis of tree vitality assessment. Trees with per hectare), BA and the number of tree species per inventory plot with superior trees were determined. A ≥50% of branch death in the crown are usually con- nonparametric Brunner–Munzel test (Brunner & sidered candidates for harvest (Kuboyama 1994). In practice, more than half of the superior trees have Munzel 2000) was then performed to examine the differences in these parameters between inventory been logged within a few years after death. A dead B. maximowicziana tree can be sold at an extremely plots with and without superior trees. Stand para- high price if it is large enough, because after death, meters (including all species) were computed for plots with superior trees of each of the five focal the heartwood often turns an elegant pink that buyers prefer (Kuboyama 1993). On the other hand, K. sep- species. temlobus should be harvested while alive, because the We examined the abundance (number of tree indi- viduals observed) for each of the five focal species in species is prone to rapidly losing timber quality and market value after the death (Kuboyama 1994). the inventory plots by graphing rank-species abun- dance diagrams, with log-abundance for mean tree density or BA plotted on the y-axis, and species ranked Data collection and analysis consecutively by abundance on the x-axis (McGill et al. 2007). Species mean abundances based on tree density A total of 2906 inventory plots was established and (Figure 3) and BA (Figure 4) were computed for the measured during 2006–2013 within the UTokyo inventory plots where superior trees of each of the focal Hokkaido Forest (Owari 2013). Excluding plots species were found and also for all inventory plots. located in plantation forests, we used the data from Relative abundance (number of trees of a species as a 2105 inventory plots for our preliminary analysis. percentage of the total number of trees) was calculated These plots had an aggregated area of 452.4 ha, and INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 77 Figure 2. Major high-value hardwood species at the University of Tokyo Hokkaido Forest: (a) monarch birch (B. maximowiczi- ana), (b) castor aralia (K. septemlobus), (c) Japanese oak (Q. crispula) and (d) Japanese ash (F. mandshurica). Figure 3. Rank-species abundance diagram using mean tree density, for inventory plots in which superior trees of particular high-value species were observed, compared to all inventory plots, at the University of Tokyo Hokkaido Forest: (a) T. japonica, (b) K. septemlobus, (c) F. mandshurica, (d) B. maximowicziana and (e) Q. crispula. Log-abundance represented by the mean tree density (number of tree individuals per hectare) is plotted on the y-axis, while species are ranked consecutively on the x-axis. The solid line indicates the abundance of each species for the inventory plots in which the superior trees were observed (see Table 1), while the dashed line represents all inventory plots (n = 2105). The ranks of the particular high-value tree species are marked by a solid circle (the inventory plots in which superior trees were observed) and an open circle (all inventory plots). 78 T. OWARI ET AL. Figure 4. Rank-species abundance diagrams using mean basal area, for inventory plots in which superior trees of particular high-value species were observed, compared to all inventory plots, at the University of Tokyo Hokkaido Forest: (a) T. japonica, (b) K. septemlobus, (c) F. mandshurica, (d) B. maximowicziana and (e) Q. crispula. Log-abundance represented by the mean basal area is plotted on the y-axis, while species are ranked consecutively on the x-axis. The solid line indicates the abundance of each species for the inventory plots in which the superior trees were observed (see Table 1), while the dashed line represents all inventory plots (n = 2105). The ranks of the particular high-value tree species are marked by a solid circle (the inventory plots in which superior trees were observed) and an open circle (all inventory plots). Figure 5. Average diameter class densities for particular high-value species in the inventory plots at the University of Tokyo Hokkaido Forest: (a) T. japonica, (b) K. septemlobus, (c) F. mandshurica, (d) B. maximowicziana and (e) Q. crispula. The solid line indicates the diameter class densities for the inventory plots in which superior trees for the particular species were observed (see Table 1), and the densities of the superior trees in each DBH class are marked by solid circles. The dashed line represents the diameter class densities for the particular species in the inventory plots in which the superior trees for the particular species were not found. for each of the five focal species. A Wilcoxon signed- DBH) between inventory plots with and without super- rank test was used to compare the relative abundance ior trees. in tree density and BA for each focal species, from plots The economics of high-value timber species was with superior trees for that species and from all plots. also examined. The UTokyo Hokkaido Forest has Average diameter class densities (Figure 5)were also been selling fancy hardwood logs produced from determined for inventory plots with superior trees and superior trees at the auction market in Asahikawa, also for the inventory plots without superior trees. A central Hokkaido (Okamura & Goto 2004), once or Brunner–Munzel test was performed to compare the twice a year since 1987 (Kuboyama 1994). The unit diameter class densities of large-sized trees (≥50 cm prices and total sales of fancy logs for each species in INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 79 January 2014 and January 2015 were calculated using plant species increases, and the habitat for animals the sales record at the auction market. is enhanced in the mature stage of stand develop- ment (Fujimori 2001). Since BA has a linear rela- tion to the above-ground biomass (Chiba 1998), there were greater biomass and carbon stocks in Results and discussion stands where superior trees grew. By carefully Stand type of ‘superior trees’ managing superior trees and the surroundings, tree species diversity and high carbon storage may A total of 327,198 naturally grown trees ≥ 5cmDBH have been maintained. of 53 species was found within the 2105 inventory Although stand parameters varied widely for each plots. The most common species was the conifer species, superior K. septemlobus trees tended to occur Abies sachalinensis (F. Schmidt) Mast. (80,758 trees; –1 in plots with relatively high tree density (862 trees ha 25% of the total), followed by T. japonica (34,495 trees; 2 –1 and large BA (34.1 m ha )(Table 1). The number of 11%), Acer pictum Thunb. (31,279 trees; 10%) and tree species was relatively large in plots with superior B. Picea jezoensis (Siebold & Zucc.) Carrière (22,960 maximowicziana trees (19.1 species; Table 1). Superior trees; 7%). High-value timber species of B. maximo- trees of F. mandshurica and T. japonica were found in wicziana (9947 trees; 3%), Q. crispula (7980 trees; 2%), plots having relatively lower tree density (660 and 648 K. septemlobus (5995 trees; 2%) and F. mandshurica –1 trees ha ) and fewer tree species (14.2 and 16.1 spe- (3467 trees; 1%) were relatively rare in the inventory cies) (Table 1), probably because these two species are plots. often found in mixed stands dominated by broad- We found 57 superior trees of 11 broad-leaved spe- leaved species, which typically have lower density cies in 2.2% of the inventory plots (46 out of 2105 plots; than stands dominated by coniferous species (The Table 1). The mean density of superior trees over the –1 Tokyo University Forest in Hokkaido 2007). inventory plots was calculated at 0.13 trees ha .The mean DBH of superior trees was 62.3 cm, and ranged between 40 and 94 cm. Among superior trees of all Relative species abundance and size distributions species, the species in this study (T. japonica, K. sep- temlobus, F. mandshurica, B. maximowicziana and Q. Figure 3 shows rank-species abundance for inven- crispula) had the most individual trees. Other species tory plots in which superior trees of the focal spe- with superior trees included A. pictum Thunb., Betula cies were observed, compared to the rank-species ermanii Cham., Cercidiphyllum japonicum Sieb. & Zucc, abundance for all inventory plots. There were more Phellodendron amurense Rupr., T. maximowicziana trees of K. septemlobus in inventory plots with Shiras. and Ulmus laciniata (Trautv.) Mayr. superior trees of this species than in plots without Within the inventory plots in which superior superior trees of K. septemlobus.The same wastrue trees were found, the mean density of all tree spe- for F. mandshurica and Q. crispula.The seed size is –1 cies was 725 trees ha . The difference in total tree relatively large in F. mandshurica (>100 mg) and Q. density between plots with and without superior crispula (>2000 mg) (Seiwa 1994). Although K. sep- trees was not significant (p = 0.38). The mean BA temlobus produces small seeds (>1 mg), the disper- 2 –1 (31.2 m ha )and themeannumberofspecies sal depends on birds. For these species, superior observed (17.0 species) were both significantly lar- trees may have promoted their own abundance ger in inventory plots with superior trees than in within inventory plots by dispersing more seeds to inventory plots without superior trees (p < 0.001). the immediate surroundings. The presence of a These results indicated that superior trees of all same-species superior tree did not affect the ranks species generally grew in mature and species-rich of species abundance in T. japonica and B. max- stands. As the understorey develops, the number of imowicziana, which have wind-dispersed seeds, and Table 1. Stand parameters of the inventory plots in which superior trees were found (mean ± s.d.) at the University of Tokyo Hokkaido Forest. Superior tree Stand parameter –1 2 –1 Species Number of trees DBH (cm) Number of observed plots Tree density (ha ) Basal area (m ha ) Number of species T. japonica 12 59.2 ± 5.9 12 648 ± 114 31.4 ± 5.1 16.1 ± 3.9 K. septemlobus 12 66.3 ± 5.6 12 862 ± 241 34.1 ± 3.9 17.8 ± 3.6 F. mandshurica 11 57.5 ± 9.8 9 660 ± 268 29.9 ± 6.1 14.2 ± 1.9 B. maximowicziana 7 60.9 ± 6.7 7 764 ± 124 30.4 ± 4.8 19.1 ± 4.2 Q. crispula 6 73.0 ± 10.4 6 679 ± 113 30.9 ± 2.8 17.3 ± 2.2 Other spp. 9 60.9 ± 6.0 8 627 ± 321 29.1 ± 5.3 17.4 ± 3.5 Total 57 62.3 ± 8.8 46 725 ± 237 31.2 ± 5.1 17.0 ± 3.7 (Other plots) (2059) (731 ± 357) (26.7 ± 8.2) (14.6 ± 4.4) All live trees with DBH ≥ 5 cm were measured in each plot. The plot size was normally 0.25 ha. Nine plots had ≥2 superior trees. 80 T. OWARI ET AL. whose seeds were probably dispersed mostly outside January 2015 (Table 2). The total sales from fancy hardwood logs (41.6 million JPY) accounted for 25% of the inventory plots. We obtained similar results when the species abundance distribution in terms of of the total income (168.3 million JPY) during the mean BA was examined (Figure 4). For the five period for the UTokyo Hokkaido Forest. Among the species sold, B. maximowicziana was the most expen- high-value tree species focused on in this study, the mean relative abundance was highest in T. sive, and for this species the highest log price in –3 japonica (18.3% in tree density and 23.2% in BA) January 2015 was 2,370,600 JPY (20,090 USD) m . and lowest in B. maximowicziana (2.1% in tree K. septemlobus had the second highest log price, –3 density and 6.3% in BA). In the five species inves- which was 880,200 JPY (7459 USD) m in the tigated, the relative abundance was significantly same year. These two species are mainly used to higher in BA than in tree density (p <0.05),indi- produce face veneer for decorative plywood. For F. cating the relative dominance of large-sized trees mandshurica, which is mainly used for furniture, the –3 within these species. average price in 2014 was 73,351 JPY (622 USD) m . Figure 5 shows the mean tree diameter class Market preference, resource scarcity, as well as the densities in inventory plots in which superior trees type of final products may have affected the market were observed for each of the five focal species, price of high-value timber species. Since the imple- compared to the mean diameter class densities of mentation of single-tree management requires costs the same species in the inventory plots in which the and efforts for searching for, marking and periodically superior trees for the particular species were not monitoring individual trees, it is feasible only when observed. In the inventory plots having superior log price is very high. trees, large-sized trees were mostly registered as superior trees. For all five species, the diameter Conclusions class densities of large-sized trees (≥50 cm DBH) were significantly greater in the inventory plots with At the UTokyo Hokkaido Forest, the single-tree man- superior trees than the inventory plots without agement system facilitates the sustainable use of high- superior trees (p < 0.001). Under the single-tree value timber species by explicitly listing the numbers, management system, these superior trees have been attributes and locations of superior trees in the for- excluded from periodic selection harvests. This ests. The system also maintains large-sized canopy result indicates that the single-tree management trees in the forest, which, in turn, maintains the contributes to forest structural diversity through high carbon storage and structural heterogeneity the protection of large-sized high-value timber that supports species diversity by providing abundant trees, which are often preferred by cavity nesting seed sources and diverse wildlife habitat. The produc- birds (Suzuki et al. 1983) and perching raptors tion of fancy wood from high-value timber species (Berkelman et al. 2002). A relatively few trees in brings significant income through extremely high log the largest size classes dominate stand-level above- prices. ground biomass (Enquist & Niklas 2001;Lutz etal. Although the risks of illegal logging are currently 2012). negligible in the country, the precise locations of superior trees may need to be kept secret (Lindenmayer et al. 2014). Due to budget and labour Economics of high-value timber constraints, however, the periodic field assessment of The high-value hardwoods B. maximowicziana, K. superior trees across the management area may septemlobus, F. mandshurica and C. japonicum were become difficult in the near future. Single-tree man- sold at the auction market in January 2014 and agement is most likely to be applicable to large-sized Table 2. Sales of fancy hardwood logs by auction from the University of Tokyo Hokkaido Forest between January 2014 and January 2015, in Asahikawa, central Hokkaido. Average price Highest price Total sales –3 –3 Volume (JPY m ) (JPY m ) (JPY) 3 –3 –3 Species Number of logs (m ) (USD m ) (USD m ) (USD) B. maximowicziana 90 60.346 584,260 2,370,600 35,257,770 (4951) (20,090) (298,795) K. septemlobus 13 13.037 392.920 880,200 5,122,501 (3330) (7459) (43,411) F. mandshurica 5 5.174 73,351 233,100 605,368 (622) (1975) (5130) C. japonicum 2 3.451 175,504 190,680 605,664 (1487) (1616) (5133) Total 110 82.008 507,162 – 41,591,303 (4298) (–) (352,469) 1 USD = 118 JPY (as of January 2015). Consumption tax is included. INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 81 Kuboyama H. 1993. Koyoju yuryo zai no seisan hanbai ni tree individuals of valuable species having extremely kansuru keizai bunseki: Tokyo Daigaku Hokkaido high timber prices. 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Single-tree management for high-value timber species in a cool-temperate mixed forest in northern Japan

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Taylor & Francis
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© 2016 Informa UK Limited, trading as Taylor & Francis Group
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2151-3732
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2151-3740
DOI
10.1080/21513732.2016.1163734
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Abstract

INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT, 2016 VOL. 12, NOS. 1–2, 74–82 http://dx.doi.org/10.1080/21513732.2016.1163734 Special Issue: Synergies between biodiversity and timber management Single-tree management for high-value timber species in a cool-temperate mixed forest in northern Japan a a a a b Toshiaki Owari , Koji Okamura , Kenji Fukushi , Hisatomi Kasahara and Shinichi Tatsumi The University of Tokyo Hokkaido Forest, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Furano, Japan; Division of Natural Environment and Information Research, Graduate School of Environmental and Information Science, Yokohama National University, Yokohama, Japan ABSTRACT ARTICLE HISTORY Received 30 April 2015 High-value hardwood species such as monarch birch (Betula maximowicziana) and castor Accepted 6 March 2016 aralia (Kalopanax septemlobus) are important economic and ecological elements of cool- temperate mixed forests in northern Japan. This article presents the single-tree management EDITED BY system for high-value timber species as practised for 50 years at the University of Tokyo Nicholas Brokaw Hokkaido Forest. Nearly 2000 valuable broad-leaved trees meeting the size and quality criteria KEYWORDS have been registered as ‘superior trees’, and their status is periodically monitored for timing Auction market; fancy wood; of harvest. A case study was conducted using 2105 inventory plots to characterize the stand high-value tree species; types in which superior trees occur. A total of 57 superior trees of 11 broad-leaved species single-tree registry system; was found in 2.2% of the inventory plots. The results indicated that superior trees generally superior tree; The University grew in mature species-rich stands. Superior trees of some species may have promoted their of Tokyo Hokkaido Forest abundance by dispersing relatively more seeds to the surroundings. Single-tree management facilitates the sustainable use of high-value timber species by explicitly monitoring the numbers, attributes and locations of superior trees, and contributes to conserving stand structural diversity through protection of these large-sized canopy trees, which promotes ecological values such as biomass and carbon storage, species diversity, seed abundance and bird habitat. The production of fancy wood from superior trees earns significant income –3 through extremely high log prices (maximum > 20,000 USD m ). forest ecosystems (Lindenmayer et al. 2012), with Introduction regard to biomass, carbon storage (Lutz et al. 2012; High-value timber species are those used for products Sist et al. 2014; Kauppi et al. 2015) and structural with extremely high commercial value. The monarch heterogeneity (Lutz et al. 2013). Their social and birch (Betula maximowicziana Regel) and castor ara- cultural values are also significant (Blicharska & lia (Kalopanax septemlobus (Thunb.) Koidz) are the Mikusiński 2014). Management of valuable large old most valuable timber species of cool-temperate mixed trees may help conserve both the economic value and forests in northern Japan, fetching log prices of up to the biodiversity of the forests they inhabit. –3 20,000 USD m . Other high-value species include Due to their economic value, high-value timber big-leaf mahogany (Swietenia macrophylla King) and species are often intensively harvested with little ipê (Tabebuia spp.) in Latin America (Kometter et al. attention to the impacts on their population struc- 2004; Grogan et al. 2010), African mahogany tures and dynamics (Schulze et al. 2008). They suffer (Entandrophragma spp.) in Africa (Romeiras et al. from illegal logging (Ward et al. 2008) and are 2014) and rosewood (Dalbergia cochinchinensis becoming increasingly scarce in heavily logged forests Pierre) in Southeast Asia (So et al. 2010). In Europe, (Prates-Clark et al. 2008). The most valuable timber valuable broad-leaved genera (Acer, Alnus, Betula, species are often the most threatened ones (So et al. Fraxinus, Juglans, Prunus, Sorbus, Tilia and Ulmus 2010). Thus, fundamental changes in forest manage- spp.) produce high-value timber that is used in the ment practices are urgently needed to conserve exist- veneer and furniture industries (Hemery et al. 2008; ing trees of high-value timber species, as well as forest Oosterbaan et al. 2009). biomass and structural heterogeneity. Lindenmayer Even though high-value timber species typically et al. (2014) suggested creating a tree registry system occur at very low densities (Schulze et al. 2008), that aims at promoting their protection. He suggested they play important economic and ecological roles that single-tree management of valuable tree indivi- in forest management (Oosterbaan et al. 2009). duals should replace unplanned harvests by explicitly Trees with high economic value are often large and identifying tree attributes and locations in forests. old. Large old trees are key structural attributes in CONTACT Toshiaki Owari owari@uf.a.u-tokyo.ac.jp The University of Tokyo Hokkaido Forest, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 9-61 Yamabe-Higashimachi, Furano 079-1563, Japan © 2016 Informa UK Limited, trading as Taylor & Francis Group INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 75 In this article, we describe single-tree management from a large area (Zingg 1999). The cutting cycle is either 15 or 20 years, depending upon stand growth of high-value timber species in a cool-temperate mixed forest in northern Japan. A case study was rates and accessibility. In each managed area, the rate conducted at the University of Tokyo (UTokyo) of tree removal is 10–17% of the growing stock per cutting cycle, which is lower than the stock growth Hokkaido Forest, where single-tree management for high-value hardwoods has been practised since the rate (The University of Tokyo Hokkaido Forest 2012). Logging operations typically use felling with mid-1960s, and nearly 2000 trees with superior tim- chainsaws and skidding of the felled stems by a ber quality have been registered as ‘superior trees’ and monitored on an individual-tree basis. Our spe- winch-equipped crawler tractor (Tatsumi et al. 2014). The mean annual tree removal and timber cific objectives were (1) to identify how stands in sales (stumpage and logs) during 2006–2010 were which superior trees occur differ from stands without such trees, in terms of tree density, basal area (BA) 23,100 m and 120 million Japanese Yen (JPY) and species richness and (2) based on differences (approximately 1 million USD), respectively (The between stands with and without superior trees, to University of Tokyo Hokkaido Forest 2012). consider how single-tree management for superior trees might help to conserve forest biodiversity. We Single-tree management for ‘superior trees’ also present the economic benefits of single-tree management for high-value trees. To maintain and sustainably produce high-value tim- ber in managed stands, the UTokyo Hokkaido Forest has been practicing the single-tree management sys- Methods tem since 1965 (Shibata 1988; Yamamoto et al. 1989; Yamamoto 1990). The system has three components: UTokyo Hokkaido Forest and management (1) single-tree selection and registration, (2) measure- policies ment and assessment and (3) periodic monitoring for The UTokyo Hokkaido Forest was established in 1899, optimal harvest. when national forests were transferred from the Under the single-tree management system, large- Ministry of Home Affairs to the UTokyo. It is located sized canopy trees with high timber quality and value in the centre of Hokkaido Island, in northernmost have been individually selected and registered as Japan (43°10′–20′ N, 142°18′–40′ E, 190–1459 m asl), ‘superior trees’ (The Tokyo University Forest in and has an area of 22,716 ha. The mean annual tem- Hokkaido 2012). Operational guidelines for selecting perature and precipitation at the arboretum of the superior trees include diameter at breast height (DBH Forest (230 m asl) during 2001‒2008 were 6.3°C and ≥ 40 cm), crown height (≥4 m) and estimated length 1210 mm, respectively (The University of Tokyo of butt log (≥4 m) (The University of Tokyo Hokkaido Forest 2012). Snow (maximum 83 cm in Hokkaido Forest 2012). There are also qualitative depth) usually covers the ground from late criteria for single-tree selection: the trunk should be November to early April. The typical substrate and straight, the cross section should be a circle and the soil type are welded tuff and dark-brown forest soil. stem should have few defects such as bending, twist- The Forest is situated in the pan-mixed forest zone ing, knots from branches or dormant buds, and (Tatewaki 1958), which is transitional between decid- decay. uous forests in the cool-temperate zone and coniferous All superior trees are numbered, and DBH, species forests in the Sub-Boreal zone. Uneven-aged mixed name, tree vitality (based on visual assessment of tree forests with coniferous and broad-leaved tree species crown) and stem damage (if any) are recorded. The are the main vegetation cover. As of 2011, the total geographic locations have been partly obtained using –1 and mean ha growing stock of the Forest were 4.8 a global navigation satellite system (GNSS) receiver 3 3 –1 million m and 211 m ha ,respectively (The with positional accuracy < 5 m (Owari et al. 2011; University of Tokyo Hokkaido Forest 2012). Tokuni et al. 2016). As shown in Figure 1, registered A large-scale and long-term experiment on the superior trees are sparsely distributed over the man- stand-based silvicultural management system agement area. This precise information on individual (Takahashi 1961; Watanabe & Sasaki 1994) has been tree positions is, therefore, crucial for single-tree conducted at the UTokyo Hokkaido Forest since management practices. The status of registered super- 1958. The idea behind the system is that management ior trees is periodically monitored by tree-marking should be adapted to the conditions of each stand to crews for harvest at the optimal time (see below). maximize the multiple public and economic func- A total of 1952 superior trees from 19 valuable tions of forest ecosystems (Takahashi 2001). Single- broad-leaved species was listed on the registry as of tree selection harvest has been implemented as the September 2014. Major species in the registry and main silvicultural system at the Forest, in which trees included in this study were K. septemlobus (Thunb.) are periodically selected and harvested individually Koidz, Quercus crispula Blume, Tilia japonica (Miq.) 76 T. OWARI ET AL. Figure 1. An example of location map for registered superior trees (Compartment no. 56) at the University of Tokyo Hokkaido Forest. Simonk., B. maximowicziana Regel and Fraxinus the plot size was normally 0.25 ha (50 m × 50 m). The mandshurica Rupr. (Figure 2). Their mean DBH species and DBH classes (2 cm intervals) for all live was 64.3 cm, with a range of 40–110 cm. Shibano trees with DBH ≥ 5 cm were recorded in each plot. et al. (1995) found that superior B. maximowicziana We determined whether registered superior trees trees that had been harvested during 1988–1993 ran- occurred in each plot from the measurement record. ged between 105 and 316 years in age and 48–108 cm For this study, we focused on T. japonica, K. septem- lobus, F. mandshurica, B. maximowicziana and Q. in DBH. According to the 10-year forest management plan crispula. for 2011–2020, 100 m of superior trees are to be To characterize the stands where superior trees of these five species occur and that are under single-tree harvested annually (The University of Tokyo management, tree density (number of tree individuals Hokkaido Forest 2012). Superior trees are harvested on the basis of tree vitality assessment. Trees with per hectare), BA and the number of tree species per inventory plot with superior trees were determined. A ≥50% of branch death in the crown are usually con- nonparametric Brunner–Munzel test (Brunner & sidered candidates for harvest (Kuboyama 1994). In practice, more than half of the superior trees have Munzel 2000) was then performed to examine the differences in these parameters between inventory been logged within a few years after death. A dead B. maximowicziana tree can be sold at an extremely plots with and without superior trees. Stand para- high price if it is large enough, because after death, meters (including all species) were computed for plots with superior trees of each of the five focal the heartwood often turns an elegant pink that buyers prefer (Kuboyama 1993). On the other hand, K. sep- species. temlobus should be harvested while alive, because the We examined the abundance (number of tree indi- viduals observed) for each of the five focal species in species is prone to rapidly losing timber quality and market value after the death (Kuboyama 1994). the inventory plots by graphing rank-species abun- dance diagrams, with log-abundance for mean tree density or BA plotted on the y-axis, and species ranked Data collection and analysis consecutively by abundance on the x-axis (McGill et al. 2007). Species mean abundances based on tree density A total of 2906 inventory plots was established and (Figure 3) and BA (Figure 4) were computed for the measured during 2006–2013 within the UTokyo inventory plots where superior trees of each of the focal Hokkaido Forest (Owari 2013). Excluding plots species were found and also for all inventory plots. located in plantation forests, we used the data from Relative abundance (number of trees of a species as a 2105 inventory plots for our preliminary analysis. percentage of the total number of trees) was calculated These plots had an aggregated area of 452.4 ha, and INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 77 Figure 2. Major high-value hardwood species at the University of Tokyo Hokkaido Forest: (a) monarch birch (B. maximowiczi- ana), (b) castor aralia (K. septemlobus), (c) Japanese oak (Q. crispula) and (d) Japanese ash (F. mandshurica). Figure 3. Rank-species abundance diagram using mean tree density, for inventory plots in which superior trees of particular high-value species were observed, compared to all inventory plots, at the University of Tokyo Hokkaido Forest: (a) T. japonica, (b) K. septemlobus, (c) F. mandshurica, (d) B. maximowicziana and (e) Q. crispula. Log-abundance represented by the mean tree density (number of tree individuals per hectare) is plotted on the y-axis, while species are ranked consecutively on the x-axis. The solid line indicates the abundance of each species for the inventory plots in which the superior trees were observed (see Table 1), while the dashed line represents all inventory plots (n = 2105). The ranks of the particular high-value tree species are marked by a solid circle (the inventory plots in which superior trees were observed) and an open circle (all inventory plots). 78 T. OWARI ET AL. Figure 4. Rank-species abundance diagrams using mean basal area, for inventory plots in which superior trees of particular high-value species were observed, compared to all inventory plots, at the University of Tokyo Hokkaido Forest: (a) T. japonica, (b) K. septemlobus, (c) F. mandshurica, (d) B. maximowicziana and (e) Q. crispula. Log-abundance represented by the mean basal area is plotted on the y-axis, while species are ranked consecutively on the x-axis. The solid line indicates the abundance of each species for the inventory plots in which the superior trees were observed (see Table 1), while the dashed line represents all inventory plots (n = 2105). The ranks of the particular high-value tree species are marked by a solid circle (the inventory plots in which superior trees were observed) and an open circle (all inventory plots). Figure 5. Average diameter class densities for particular high-value species in the inventory plots at the University of Tokyo Hokkaido Forest: (a) T. japonica, (b) K. septemlobus, (c) F. mandshurica, (d) B. maximowicziana and (e) Q. crispula. The solid line indicates the diameter class densities for the inventory plots in which superior trees for the particular species were observed (see Table 1), and the densities of the superior trees in each DBH class are marked by solid circles. The dashed line represents the diameter class densities for the particular species in the inventory plots in which the superior trees for the particular species were not found. for each of the five focal species. A Wilcoxon signed- DBH) between inventory plots with and without super- rank test was used to compare the relative abundance ior trees. in tree density and BA for each focal species, from plots The economics of high-value timber species was with superior trees for that species and from all plots. also examined. The UTokyo Hokkaido Forest has Average diameter class densities (Figure 5)were also been selling fancy hardwood logs produced from determined for inventory plots with superior trees and superior trees at the auction market in Asahikawa, also for the inventory plots without superior trees. A central Hokkaido (Okamura & Goto 2004), once or Brunner–Munzel test was performed to compare the twice a year since 1987 (Kuboyama 1994). The unit diameter class densities of large-sized trees (≥50 cm prices and total sales of fancy logs for each species in INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 79 January 2014 and January 2015 were calculated using plant species increases, and the habitat for animals the sales record at the auction market. is enhanced in the mature stage of stand develop- ment (Fujimori 2001). Since BA has a linear rela- tion to the above-ground biomass (Chiba 1998), there were greater biomass and carbon stocks in Results and discussion stands where superior trees grew. By carefully Stand type of ‘superior trees’ managing superior trees and the surroundings, tree species diversity and high carbon storage may A total of 327,198 naturally grown trees ≥ 5cmDBH have been maintained. of 53 species was found within the 2105 inventory Although stand parameters varied widely for each plots. The most common species was the conifer species, superior K. septemlobus trees tended to occur Abies sachalinensis (F. Schmidt) Mast. (80,758 trees; –1 in plots with relatively high tree density (862 trees ha 25% of the total), followed by T. japonica (34,495 trees; 2 –1 and large BA (34.1 m ha )(Table 1). The number of 11%), Acer pictum Thunb. (31,279 trees; 10%) and tree species was relatively large in plots with superior B. Picea jezoensis (Siebold & Zucc.) Carrière (22,960 maximowicziana trees (19.1 species; Table 1). Superior trees; 7%). High-value timber species of B. maximo- trees of F. mandshurica and T. japonica were found in wicziana (9947 trees; 3%), Q. crispula (7980 trees; 2%), plots having relatively lower tree density (660 and 648 K. septemlobus (5995 trees; 2%) and F. mandshurica –1 trees ha ) and fewer tree species (14.2 and 16.1 spe- (3467 trees; 1%) were relatively rare in the inventory cies) (Table 1), probably because these two species are plots. often found in mixed stands dominated by broad- We found 57 superior trees of 11 broad-leaved spe- leaved species, which typically have lower density cies in 2.2% of the inventory plots (46 out of 2105 plots; than stands dominated by coniferous species (The Table 1). The mean density of superior trees over the –1 Tokyo University Forest in Hokkaido 2007). inventory plots was calculated at 0.13 trees ha .The mean DBH of superior trees was 62.3 cm, and ranged between 40 and 94 cm. Among superior trees of all Relative species abundance and size distributions species, the species in this study (T. japonica, K. sep- temlobus, F. mandshurica, B. maximowicziana and Q. Figure 3 shows rank-species abundance for inven- crispula) had the most individual trees. Other species tory plots in which superior trees of the focal spe- with superior trees included A. pictum Thunb., Betula cies were observed, compared to the rank-species ermanii Cham., Cercidiphyllum japonicum Sieb. & Zucc, abundance for all inventory plots. There were more Phellodendron amurense Rupr., T. maximowicziana trees of K. septemlobus in inventory plots with Shiras. and Ulmus laciniata (Trautv.) Mayr. superior trees of this species than in plots without Within the inventory plots in which superior superior trees of K. septemlobus.The same wastrue trees were found, the mean density of all tree spe- for F. mandshurica and Q. crispula.The seed size is –1 cies was 725 trees ha . The difference in total tree relatively large in F. mandshurica (>100 mg) and Q. density between plots with and without superior crispula (>2000 mg) (Seiwa 1994). Although K. sep- trees was not significant (p = 0.38). The mean BA temlobus produces small seeds (>1 mg), the disper- 2 –1 (31.2 m ha )and themeannumberofspecies sal depends on birds. For these species, superior observed (17.0 species) were both significantly lar- trees may have promoted their own abundance ger in inventory plots with superior trees than in within inventory plots by dispersing more seeds to inventory plots without superior trees (p < 0.001). the immediate surroundings. The presence of a These results indicated that superior trees of all same-species superior tree did not affect the ranks species generally grew in mature and species-rich of species abundance in T. japonica and B. max- stands. As the understorey develops, the number of imowicziana, which have wind-dispersed seeds, and Table 1. Stand parameters of the inventory plots in which superior trees were found (mean ± s.d.) at the University of Tokyo Hokkaido Forest. Superior tree Stand parameter –1 2 –1 Species Number of trees DBH (cm) Number of observed plots Tree density (ha ) Basal area (m ha ) Number of species T. japonica 12 59.2 ± 5.9 12 648 ± 114 31.4 ± 5.1 16.1 ± 3.9 K. septemlobus 12 66.3 ± 5.6 12 862 ± 241 34.1 ± 3.9 17.8 ± 3.6 F. mandshurica 11 57.5 ± 9.8 9 660 ± 268 29.9 ± 6.1 14.2 ± 1.9 B. maximowicziana 7 60.9 ± 6.7 7 764 ± 124 30.4 ± 4.8 19.1 ± 4.2 Q. crispula 6 73.0 ± 10.4 6 679 ± 113 30.9 ± 2.8 17.3 ± 2.2 Other spp. 9 60.9 ± 6.0 8 627 ± 321 29.1 ± 5.3 17.4 ± 3.5 Total 57 62.3 ± 8.8 46 725 ± 237 31.2 ± 5.1 17.0 ± 3.7 (Other plots) (2059) (731 ± 357) (26.7 ± 8.2) (14.6 ± 4.4) All live trees with DBH ≥ 5 cm were measured in each plot. The plot size was normally 0.25 ha. Nine plots had ≥2 superior trees. 80 T. OWARI ET AL. whose seeds were probably dispersed mostly outside January 2015 (Table 2). The total sales from fancy hardwood logs (41.6 million JPY) accounted for 25% of the inventory plots. We obtained similar results when the species abundance distribution in terms of of the total income (168.3 million JPY) during the mean BA was examined (Figure 4). For the five period for the UTokyo Hokkaido Forest. Among the species sold, B. maximowicziana was the most expen- high-value tree species focused on in this study, the mean relative abundance was highest in T. sive, and for this species the highest log price in –3 japonica (18.3% in tree density and 23.2% in BA) January 2015 was 2,370,600 JPY (20,090 USD) m . and lowest in B. maximowicziana (2.1% in tree K. septemlobus had the second highest log price, –3 density and 6.3% in BA). In the five species inves- which was 880,200 JPY (7459 USD) m in the tigated, the relative abundance was significantly same year. These two species are mainly used to higher in BA than in tree density (p <0.05),indi- produce face veneer for decorative plywood. For F. cating the relative dominance of large-sized trees mandshurica, which is mainly used for furniture, the –3 within these species. average price in 2014 was 73,351 JPY (622 USD) m . Figure 5 shows the mean tree diameter class Market preference, resource scarcity, as well as the densities in inventory plots in which superior trees type of final products may have affected the market were observed for each of the five focal species, price of high-value timber species. Since the imple- compared to the mean diameter class densities of mentation of single-tree management requires costs the same species in the inventory plots in which the and efforts for searching for, marking and periodically superior trees for the particular species were not monitoring individual trees, it is feasible only when observed. In the inventory plots having superior log price is very high. trees, large-sized trees were mostly registered as superior trees. For all five species, the diameter Conclusions class densities of large-sized trees (≥50 cm DBH) were significantly greater in the inventory plots with At the UTokyo Hokkaido Forest, the single-tree man- superior trees than the inventory plots without agement system facilitates the sustainable use of high- superior trees (p < 0.001). Under the single-tree value timber species by explicitly listing the numbers, management system, these superior trees have been attributes and locations of superior trees in the for- excluded from periodic selection harvests. This ests. The system also maintains large-sized canopy result indicates that the single-tree management trees in the forest, which, in turn, maintains the contributes to forest structural diversity through high carbon storage and structural heterogeneity the protection of large-sized high-value timber that supports species diversity by providing abundant trees, which are often preferred by cavity nesting seed sources and diverse wildlife habitat. The produc- birds (Suzuki et al. 1983) and perching raptors tion of fancy wood from high-value timber species (Berkelman et al. 2002). A relatively few trees in brings significant income through extremely high log the largest size classes dominate stand-level above- prices. ground biomass (Enquist & Niklas 2001;Lutz etal. Although the risks of illegal logging are currently 2012). negligible in the country, the precise locations of superior trees may need to be kept secret (Lindenmayer et al. 2014). Due to budget and labour Economics of high-value timber constraints, however, the periodic field assessment of The high-value hardwoods B. maximowicziana, K. superior trees across the management area may septemlobus, F. mandshurica and C. japonicum were become difficult in the near future. Single-tree man- sold at the auction market in January 2014 and agement is most likely to be applicable to large-sized Table 2. Sales of fancy hardwood logs by auction from the University of Tokyo Hokkaido Forest between January 2014 and January 2015, in Asahikawa, central Hokkaido. Average price Highest price Total sales –3 –3 Volume (JPY m ) (JPY m ) (JPY) 3 –3 –3 Species Number of logs (m ) (USD m ) (USD m ) (USD) B. maximowicziana 90 60.346 584,260 2,370,600 35,257,770 (4951) (20,090) (298,795) K. septemlobus 13 13.037 392.920 880,200 5,122,501 (3330) (7459) (43,411) F. mandshurica 5 5.174 73,351 233,100 605,368 (622) (1975) (5130) C. japonicum 2 3.451 175,504 190,680 605,664 (1487) (1616) (5133) Total 110 82.008 507,162 – 41,591,303 (4298) (–) (352,469) 1 USD = 118 JPY (as of January 2015). Consumption tax is included. INTERNATIONAL JOURNAL OF BIODIVERSITY SCIENCE, ECOSYSTEM SERVICES & MANAGEMENT 81 Kuboyama H. 1993. Koyoju yuryo zai no seisan hanbai ni tree individuals of valuable species having extremely kansuru keizai bunseki: Tokyo Daigaku Hokkaido high timber prices. 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Journal

International Journal of Biodiversity Science, Ecosystem Services & ManagementTaylor & Francis

Published: Jan 2, 2016

Keywords: Auction market; fancy wood; high-value tree species; single-tree registry system; superior tree; The University of Tokyo Hokkaido Forest

References