Introduction of Canadian Tree Species to the Northeast of China

0907-B1

Ben Wang^[1], Steve D’Eon and Jian Dong

Abstract

This paper describes the early results of the introduction of some Canadian tree species to Liaoning Province in Northeast China. Based on earlier trial results from the 1920s and testing over the last 20 years, some of the introduced conifers show a strong adaptability to the new ecological and climatic conditions with normal flowering and fruiting, excellent growth rates and resistance to local pests. Of the 17 introduced species tested, eastern white pine (Pinus strobus), jack pine (P. banksiana), and pitch pine (P. rigida) show the most promising results as compared to indigenous species of pine (P. tabulaeformis, P. koraiensis, P. sylvestris var. mongolica). These trial findings brought about planning for large-scale planting programs of jack pine in the current five-year plan of the provincial forestry authority. In parallel with the seed source trials, seed production areas have been established selecting promising sources and species for developing local land-races for future seed production. The application of this successful cooperation will not only increase the forest cover of Liaoning from the current 30.95% to 35% improving the environment and wood supply, but also serve as a model for the regions as well as other jurisdictions.

Introduction

The introduction of exotic tree species has been economically beneficial in many regions of the globe and is the goal of many established and new forestry programs (Morgenstern 1996). North American tree species such as Pseudotsuga menziesii, Picea sitchensis, Pinus contorta and Abies grandis have been introduced to Europe for 250 years, sometimes becoming major plantation species in some countries such as in the United Kingdom where sitka spruce is extensively planted. Similarly, fast-growing Eucalptus and Acacia species from Australia have been widely introduced and adapted to many tropical countries of the world. In contrast, Pinus radiata, a commercially unimportant tree species of Coastal central California and northern Guadalupe Island of Mexico, has been growing in large areas of Chile, South Africa, Australia and New Zealand (Morgenstern 1996).

Liaoning Province covers 146,000 km² of which 60% is considered mountainous. In the 1700’s forests of spruce and larch predominated and even the western part of Liaoning was considered forested. By 1950 forests covered only 12.9% of Liaoning with the western part even worse with only 3% forest cover. Since the implementation of an ecological construction program forest cover had been increased to 30.9% despite plantations of Larix species succumbing to disease and plantations of Pinus sylvestris var. mongolica not performing well in the long term.

The introduction of tree species to Liaoning in China began in 1923 when eastern white pine (Pinus strobus), jack pine (P. banksiana) and pitch pine (P. rigida) were introduced to the Xiongyue Arboretum, Liaoning (40^o N, 122^oE) (Yu et al. 1999). These exotic species proved to be adaptable to the local climatic and ecological conditions with normal flowering and fruiting and showing good growth with white pine the best averaging 0.309 m/year in height and 0.668 cm/year in DBH from 1975-1998. Seed from the introduced specimens of pitch pine were used to create a second generation plantation in 1940.

Unfortunately these early introductions were done without proper planning, design or seed source documentation. Since 1981 some Central and Provincial forest research agencies in China have recognized the need for collaboration in developing plans for species introduction and acclimatization of exotic northern temperate conifers (Dong et. al. 2002). Since the early 1980’s, the Liaoning Provincial Academy of Forest Sciences has cooperated on introduction trials with the Canadian Forest Service (CFS) at Petawawa. These trials were properly planned and designed to provide reliable information for practical application. Although about half the species tested showed potential for successful introduction, in this paper we describe the various site conditions, growth rates, and adaptability of the most promising species and discuss their application in Liaoning.

Methods and Material

Seeds of known origin and quality were kindly provided by the CFS’s National Tree Seed Centre from the early1980s until today. The National Tree Seed Centre hosts Canada’s depository of forest tree seeds for research purposes with seedlots carefully documented, tested, and stored. During this period seedlots of 17 tree species were shipped from Canada to the Academy of Forest Sciences in China. These seedlots represented sources from 40° to 47° N and 62° to 83° W. The seed were sown in various nurseries and manually planted at the test sites as 2+0 bare-root stock. Planting density ranged from around 1.5 m x 1.5 m to 2.0 m x 2.0 m. Most plantations were pruned at an early age.

Twenty test sites with one or more introduced species were established in six climatic zones across Liaoning (Figure 1). Usually a local species was planted at each site for comparison purposes. The climatic zones range from temperate semi-arid desert in the northwest through mountainous warm moist climate in the east to a temperate semi-moist plain in the south. The average annual temperature ranges from 5.2^oC to 10.3^oC and the frost free growing season is between 128 and 183 days. Average annual precipitation ranges from 600 to 1200 mm although the growing season precipitation can be less than 450 mm in the northwest. Precipitation in the south can be unevenly distributed with the majority of rainfall in the minor monsoon season of July and August. The soils are a brown forest soil originating mostly from weathered gneiss with a clay loam texture with a higher proportion of sand in the northwest (Ann. 1990). Survival, height, and diameter growth were measured and resistance to insects and diseases noted.

Figure 1. Current status of introduced North American conifers in Liaoning.

Results and Discussion

Eastern White Pine

White pine is a predominantly outcrossing species with a low selfing rate and extensive gene flow (Daoust and Beaulieu 2001). Range wide provenance trials in eastern North America indicated variability in growth traits among seed sources and that particular seed sources can be selected for use in certain geographic areas (Dermitt and Kettlewood 1975). Breeding programs in Quebec and Ontario used 150 and 265 families respectively (Daoust and Beaulieu 2001). Estimates are not available for the number of families required to conduct proper testing of white pine as an introduced species. In Liaoning 58 families from 33 sources were tested in 10 plantations at 8 sites.

The growth performance of this species varied greatly with the planting sites (Table 1). When comparing growth rates of the 17-18 year-old planted white pine, it is apparent that the accelerating growth period occurred 5 years earlier on the better site in the northeast area, Chingyuan County, than on the site of Xiongyue in the south. There were great differences among seed sources with the worse growing at a rate of 40-80% of the best sources (Figure 2) (Dong et. al. 2002). So far there has been no sign of damage by white pine blister rust (Cronartium ribicola) nor by weevils such as Pissodes strobi. White pine, like jack pine and pitch pine, has so far been resistant to local insects Dendrolimus tabulaeformis and Matsusuccocus Massoniana. Therefore, through trials of species and seed-source introduction, maximum gains can be obtained by selecting the most suitable species and best seed source for different climatic zones of Liaoning. White pine so far appears to be one of the most promising tree species for potential timber production as well as for landscape planting.

Figure 2. 19-year-old planted Pinus strobus in Chingyuan County.

Jack Pine

This tree species is the northern most pine in its native North America occupying sites across the continent from the eastern coast to the foothills of the Rocky Mountains in the west. Jack pine has wide genetic variation and large effective breeding populations with environmental factors appearing to be the dominant selection forces (Rudolph and Laidly 1990). Various seedling seed orchard establishment methods have been proposed with most suggesting between 100 and 200 families (Klein 1986, Jeffers 1975).

Jack pine was tested in 21 plantations at 19 testing sites using 22 seed sources comprising 200 families. The growth performance of various sources demonstrated broad adaptability and fantastic potential for wood production as well as environmental planting in Liaoning (Table 1). Results at age seven showed tremendous differences in height, diameter and crown width among the different sources with growth rates decreasing as the source latitude increased (Chang et al. 1997). The most suitable seed source was found to be around latitude 46⁰N and longitude 77-78⁰ W (Dong et. al. 2002). As a result of this testing, an additional 2.5 million seed from two sources in this geographic area were collected and shipped to Liaoning in 2002. A further 26 million seed have been requested. Jack pine has proved to be more suitable for fixing sand than the currently planted Pinus sylvestris var. mongolica on the semi-arid sandy sites of western Liaoning.

A parallel program to create seed production within Liaoning of local land races has been undertaken. In Kuan-Dien County, a 3.2 ha seed production area based on 62 families in 4 tree plots was established in 2001 (Figure 3). This seed production area will eventually become a single-tree orchard after roguing of poorly performing families. Additional seed from a seedling seed orchard containing over 700 plus trees at Spoor Lake Ontario (45^o55’N, 77^o36’W) are being collected for shipment to Liaoning to create additional breeding material for the program. About 750 seed per tree are being collected. The Spoor Lake seed orchards were established to generate material for second generation plantations. Based on the early growth performance, its tolerance to a wide range of sites and resistance to local insects and diseases, jack pine was evaluated as having a great potential for future planting in Liaoning.

Figure 3. 5-year-old planted Pinus banksiana in Kuandien County.

Pitch Pine

This tree species has very limited distribution in Canada mainly along the St. Lawrence River, Ontario and St. Antoine-Abbe in Quebec with the rest of its native range in the United States. Geographical races would not be unexpected for pitch pine given its latitudinal range (Little 1959). Contradictory results make it unclear whether genetic variation is greater within or between populations (Little and Garrett 1990). No estimates are available to guide the number of sources or families for an optimal introduction. In Liaoning 28 seed sources were introduced from the Thousand Island region of Ontario located at the northern perimeter of pitch pine’s range. Although currently isolated, this population is thought to be a relic population having previously been attached to the broader range and evidence indicates it has most of the diversity for the species (Guries and Ledig 1982).

Of the 28 sources introduced in the early 1980’s only 17 sources survived through the early testing phase with growth rates better in eastern than in drier western Liaoning but overall superior to Pinus sylvestris var. mongolica at age 10 (Table 1). As well, pitch pine proved resistant to harsh coastal conditions in a shoreline test. Based on these trials results, pitch pine can be considered a valuable introduced tree species for planting on sites where local resinous pine does poorly. Pitch pine’s sprouting ability may provide additional flexibility in achieving environmental benefits although this characteristic has yet to be explored at the introduced sites.

Table 1. Height and diameter growth of introduced jack pine, white pine, and pitch pine at various trial sites in Liaoning.

¹ Average height and diameter
² Maximum height and diameter

Conclusions

Based on the results from the ad hoc trials in 1920’s and the scientifically designed formal trials of the 1980’s, the species and seed source trials in Liaoning can be considered successful and promising. Those introduced tree species from Canada showing strong ecological adaptability, excellent growth, and resistance to local pests, ocean wind, salt spray, and desertification could be further tested in an extensive province-wide plantation program. To this end, such a large-scale planting program of white pine and jack pine is included in the current provincial five-year (2001-2005) work plan. It is expected that the planting program will increase Liaoning's forest cover from the current 30.95% to 35% improving wood supply and environmental protection. The Petawawa Research Forest is currently assisting in procuring 100 kg of jack pine seed as part of the planting program and in establishing spacing trials of white pine. Furthermore, if the operational application of these trial results prove to be successful, it can serve as a model for the Northeast region as well as other jurisdictions. In a final analysis of the early success of the species and seed source trials, the following can be identified as the major attributing factors:

1. A strong forest policy in promoting scientific research and development with long-term funding support and allocation of forest land across the host jurisdiction for duration of the planned trials.

2. Good planning in selecting the potential species and sources from the donor country to match with the ecological conditions of the planting sites in the host jurisdiction;

3. Well designed trials with clearly defined objectives and a well-trained, hard working team in place;

4. Reliable and committed cooperator(s) for seed procurement from the donor countries;

5. Availability of well established competent nursery facilities in the host jurisdiction for planting stock production and field planting; and

6. Continued efforts in maintenance, monitoring and record keeping of the trial plantings.

Acknowldegements

We thank the CFS’s National Tree Seed Centre for providing our required seedlots of many species and sources of known origin and quality over the years. We are also grateful to the funding support for the trials from the Chinese Governments to the junior author and to all those who assisted in establishing, maintaining, and monitoring the trials.

References

Ann. 1990. The forest in Liaoning (in Chinese). Editorial Committee, Department of Forestry, Compiler. Forestry Publications of China, Beijing and Liaoning Science and Technology Publication, Shenyang, Liaoning, China. 396 p.

Chang, L.G., s.H. Man and Z.Y. Chia, 1997. Seed source studies of jack pine (Pinus banksiana Lamb.) (in Chinese). Bulletin of the Northeast Forestry University 1: 19-21

Daoust, G. and J. Beaulieu, 2001. Genetics, breeding, improvement and conservation of Pinus strobus in Canada. In Sniezko, R., ed. Breeding and genetic resources of five-needle pines: growth, adaptability and pest resistance. Conference Proceedings. IUFRO Working Party 2.02.15, 23-27 July 2001, Medford, OR, USA. (in press)

Dermitt, M.E. and H. C. Kettlewood, 1975. Eastern White pine seed source variation in the northeastern United States: 16-year results. Proceedings of the Twelfth Lake States Forest Tree Improvement Conference, USDA Forest Service, General Technical Report NC-26. pp. 80-87

Dong, J. W.J. Wren, A.J. Lu, B.S.P. Wang and S. D’Eon, 2002. Introduction of North American conifers to Liaoning Province, China. Progress Report, Provincial Academy of Forest Sciences, Shenyang, Liaoning, China. 9 p.

Guries, R.P. and F.T. Ledig, 1982. Genetic diversity and population structure in pitch pine (Pinus rigida Mill.). Evolution 36(2): 387-402

Jeffers, R.M., 1975. Jack pine seedling seed orchard establishment and projected seed yields. Proceedings of the Twelfth Lake States Forest Tree Improvement Conference, USDA Forest Service, General Technical Report NC-26. pp. 16-23

Klein, J.I., 1986. Development of a jack pine seed orchard by mass selection. Forestry Chronicle 62(3): 143-146

Little, S., 1959. Silvical characteristics of pitch pine (Pinus rigida). USDA Forest Service Station Paper 119. Northeastern Forest Experiment Station, Broomall, PA. 22 p.

Little, S. and P.W. Garrett, 1990. Pitch pine. In Burns, R. M., and B. H. Honkala, technical coordinators. Silvics of North America: 1. Conifers. Agriculture Handbook 654. USDA Forest Service, Washington, DC, USA. pp. 456-462

Morgenstern, E.K., 1996. Geographic variation in forest trees: genetic basis and application of knowledge in silviculture. UBC Press, Vancouver, BC, Canada. 209 p.

Rudolph, T.D. and P.R. Laidly, 1990. Jack pine. In Burns, R. M., and B. H. Honkala, technical coordinators. Silvics of North America: 1. Conifers. Agriculture Handbook 654. USDA Forest Service, Washington, DC, USA. pp. 280-293

Yu, D.L., L.J. Sun and D. Wang, 1999. The introduction and acclimatization of five exotic pine species at Xiongyue Arboretum, Liaoning, China (in Chinese). Information Report, Liaoning Institute of Pomology, Xiongyue, Liaoning, China. 4 p.