Survival and Growth of Three Hardwood Species (Fraxinus angustifolia, Ulmus laevis and U. minor) on a BottomlandSite with Heavy Clay Soil
Seedlings of Fraxinus angustifolia Vahl., Ulmus laevis Pall. and U. minor Mill. were grown in nursery for this study. The one-year old bareroot planting stocks so produced were out-planted on the bottomland site with heavy clay soils and 360 seedlings per species was assessed two years after planting for diameter, height and survival. Significant differences were found among species in survival, diameter and height. Fraxinus angustifolia and U. laevis had excellent survival (100%) and survival was lower in U. minor (92%). Ulmus laevis had the greatest height increment (128.3 cm) and total height (187.5 cm) followed by U. minor. Fraxinus angustifolia had the lowest height increment (76.4 cm) and total height (147.2 cm). Diameter increment was also different among species and U. laevis had the greatest diameter increment (15.1 mm) and there were not significant differences among U. minor and F. angustifolia. It might be concluded that the overall survival and growth of the species were high enough on this bottomland site with heavy clay soils although there were significant differences among the species in survival and growth.
Fraxinus angustifolia Vahl. is the most common and useful native ash species due to its fast growing ability and valuable wood and dominates the bottomlands forest of northern region of Turkey. It also grows in riparian areas and founds as scattered trees or in small groups in mixed hardwood stands up to 700-800 m altitudes (Davis, 1997; Mayer and Aksoy, 1998). In Turkey, almost all ash forest areas are occupied by F. angustifolia rather than other ash species (F. excelsior and F. ornus).
Like most hardwood trees, F. angustifolia grows best on fertile, moist and well drained soils. Although its natural stands are confined to bottomlands which are considered marginal for plant growth (FRAXIGEN, 2005), it has a high growth rate on these sites (Kapucu et al., 1998). Ash species (F. excelsior and F. angustifolia) is getting more important in European forestry due to their fast growth ability and valuable woods and researches concentrate on their silviculture, breeding, genetics and gene conservation (Eriksson, 2001; FRAXIGEN, 2005). Despite its relative importance little is known about plantation success of F. angustifolia.
In Turkey, to regenerate F. angustifolia stands with Ulmus species
that are located on bottomland areas, the preferred method is clearcuting and
planting F. angustifolia. Survival and early growth are often poor in
these plantings because of their small sizes and low grade seedlings, low planting
density, neglected post planting treatments (maintenances) and excessive herbaceous
plant competition (Çiçek and Yilmaz, 2002; Çiçek
et al., 2006a, 2007). In these sites, during the early years of planting,
an excessive weed competition problem is observed because of the site conditions.
The weedy vegetation can grow up to 1.5-2 m in a few months once it comes out.
Even if elms are widespread in Turkey and Europe, they have been neglected and scarcely studied and relatively little is known population dynamics, seed biology, seedling production and field performance of these species. Elms are valuable for their hard, tough wood and they have been used for environmental purposes and amenity plantings.
Ulmus laevis Pall. and Ulmus minor Mill. are mostly grown on bottomland sites in Turkey (Davis, 1982; Mayer and Aksoy, 1998). Habitat destruction and the bark beetles (Scolytus sp.), which are the vectors of the Dutch Elm Disease fungal agent (Ophiostoma novo-ulmi), have caused enormous damage to elm populations and continues to pose a major threat to the genetic diversity of the species in Turkey and in Europe (Anşin and Özkan, 1993; Collin, 2002). Dramatic changes in the landscape are occurring on bottomland areas in Turkey, especially where land can be drained and reclaimed for agriculture or poplar cultivation (Efe and Alptekin, 1989; Çiçek, 2004; Çiçek and Yilmaz, 2006). Since natural regeneration is poor or the number of seed trees is insufficient in these bottomland sites due to small and fragmented populations, planting of Ulmus species on these sites is too important. Unfortunately, only F. angustifolia was planted on the bottomland sites but elm and other scatter species were not planted on bottomland sites until now. Thus, this study was carried out to determine the early field performance of three hardwood species (Fraxinus angustifolia, Ulmus laevis and U. minor) after 2 years planted on a bottomland site with heavy clay soils in Adapazari, Turkey.
MATERIALS AND METHODS
The field experiment was established at an artificial regeneration area
in Akyazi, Adapazari, Turkey (lat. 40°48 N, long. 30°33
E, alt. 25 m). The site formerly supported a stand of F. angustifolia
and there were also elm (Ulmus laevis, U. minor), oak (Quercus
robur, Q. hartwissiana) and maple (Acer campestre) as scatter
trees. The soil on the study site has more than 70% clay and pH 7.5-7.9 (Çiçek
et al., 2006b). The standing water (ground water) level on the site may
rise above the ground level through January-May, however summers may include
drought periods (Çiçek, 2002). The study area experiences a warm,
humid climate, with a mean annual temperature of 14.2°C, mean annual precipitation
of 800 mm and the mean growing season precipitation of 560 mm. The normal growing
season averages 230-240 days. Late summer to early fall is customarily the driest
period of the year (Anonymous, 2006). Older stands on the sites were clear felled
and then the stumps were uprooted in fall 2003. After the stumps and slashes
were disposed, the soil was first ripped and then disk.
Seedling Production and Planting
Fraxinus angustifolia seeds for this study were collected from the
natural stand found on the bottomland area of Hendek-Suleymaniye, Turkey (40°52'
N, 30°36' E, 25 m) in late October 2002. Ulmus seeds were also collected
from the same area mid-May 2003. One month warm-stratified followed by one month
cold-stratified (±4°C) F. angustifolia seeds and untreated
Ulmus seeds were sown in spring of 2003 at Hendek forest nursery (40°48'
N, 30°43' E, 60 m asl) to produce one-year old bareroot seedlings (70 seedlings
m-2). After lifting the one-year old seedlings by hand in mid-December
2003, all seedlings were graded for uniformity of height (65-75 cm), roots were
pruned and to ensure that shoots and root systems were well developed and structurally
Randomized complete block design with four replications were established at the planting area. Each experimental unit (plot) contained three rows and each row contained 30 plants. One- year old bareroot seedlings (360 seedlings per pecies) were hand planted at a spacing of 2.5x2.0 m in late December 2003. The study plots received both hand-hoeing of the soil around the seedlings and disking between rows in June 2004 and 2005.
Initial seedlings diameters (2.5 cm above the root collar) and height were
determined at plantations in the row in the middle of the plots contained 30
measurement trees immediately after planting in late December 2003. Above ground
diameter was measured instead of root collar diameter owing to the muddy site
condition. After two growing seasons, survival counts and diameter and height
measurements were taken in December 2005.
Analyses of variance (ANOVA) were used to evaluate seedling growth and survival.
Arc-sin transformation was performed on seedling survival. Significant differences
between variables were determined by Duncans New Multiple Range Test (p<0.05).
Statistical analyses were performed with the help of the computer software package
Two years after planting, survival showed significant differences among species. F. angustifolia and U. laevis had excellent survival (100%) and survival was lower in U. minor (92%) (Table 1).
Species also differed significantly in 2-year growth increment. Seedling diameter increment was the highest in U. laevis (15.1 mm) and was statistically greater than F. angustifolia and U. minor. Diameter increment was not statistically different between F. angustifolia and U. minor (8.8 and 9.3 mm, respectively) (Table 1).
|| Survival counts and growth measurements of three hardwood
species after two growing seasons
|1Means within each column followed by the same
letter are not significantly different (p<0.05)
Seedling height increment was the highest in U. laevis (128.3 cm) and the lowest in F. angustifolia (76.4 cm). Ulmus laevis seedlings were also the tallest at 187.5 cm, significantly taller than all and total diameter was also the highest at 22.9 mm.
Survival through the 2nd growing season after outplanting in three species was high (>90%) and planting tall seedlings (65-75 cm) have been shown to benefit survival.
In Turkey, to regenerate bottomland F. angustifolia stands in which U. laevis is found, the preferred method is clear cutting and planting F. angustifolia. In these sites, during the early years of planting, because of the site condition, an excessive weed competition problem is common. The weedy vegetation (Potentilla spp., Vicia spp., Plantago major, Calamintha grandiflora, Scutellaria glericulata, Lactuca serriola) can grow more than 1 m in a few months once it comes out. However, small (20-40 cm) and low quality seedlings were planted traditionally on these bottomland areas so far (Çiçek et al., 2007). This caused low seedling survival and increased the planting cost. Since seedlings have to compete with other excessive weedy vegetation after planting in artificial regeneration areas on bottomland sites, tall seedlings can protect themselves from browsing and excessive weed competition. And the present study showed that tall seedlings greatly influenced the field performance of the species.
Although this study showed that these three species could tolerate high clay content, Ulmus species grew better than F. angustifolia 2 years after planting. Ash species as in most deciduous species grow well in deep and fertile soil with pH 7-8 and high moisture content (Savill, 1992; Kerr and Cahalan, 2004; FRAXIGEN, 2005). The soil on the study site has more than 70% clay. Thus, this shows that F. angustifolia can tolerate high clay soils. But the site was not well-drained and had summer drought period which decreases growth rate of ash (Savill, 1992). Growth of F. angustifolia could be higher in a well-drained and fertilized site.
Collin (2003) stated that Ulmus are found in humid environment as well as semi-humid environment with deep soils and also step forests. Thus, the planting site might be more suitable for Ulmus growth and the results supported this idea since Ulmus species grew better than F. angustifolia.
Fraxinus angustifolia is light demanding unlike Ulmus species in its stands and it is not possible to create stands with different strata (Çiçek, 2002; FRAXIGEN, 2005; Çiçek, 2006). Since mixed stands have higher productivity than monoculture (Kelty 1992; Smith et al., 1996), Ulmus species can be planted under F. angustifolia to increase productivity and protect Ulmus species in bottomland area.
In conclusion, the present study shows that site on the bottomland areas which are not suitable for agriculture and poplar plantation can be planted by F. angustifolia and also Ulmus spp. and planting tall seedlings can be recommended to promote early establishment of the seedlings.
1: Anonymous, 2006. Adapazari meteoroloji istasyonu iklim verileri (In Turkish). Devlet Meteoroloji Isleri Genel Mudurlugu Arsivi, Ankara, Turkey.
2: Ansin, R. and Z.C. Ozkan, 1993. Tohumlu bitkiler (Spermatophyta). odunsu taksonlar. KTU. Orman Fak. Yay. No. 167/19, Trabzon, Turkey.
3: Collin, E., 2002. Strategies and guidelines for the conservation of the genetic resources of Ulmus spp. Proceedings of the Noble Hardwoods Network: Report of the 4th and 5th Meetings, September 1-2, 1999, International Plant Genetic Resources Institute, Rome, pp: 50-67
4: Collin, E., 2003. EUFORGEN Technical guidelines for genetic conservation and use for European white elm (Ulmus laevis). IPGRI, Rome.
5: Cicek, E., 2002. Stand structures and necessary silvicultural treatments on bottomland forest of Suleymaniye-Adapazari. Ph.D. Thesis, Faculty of Forestry, Istanbul University, Istanbul.
6: Cicek, E. and M. Yilmaz, 2002. The Importance of Fraxinus angustifolia subsp. oxycarpa as a fast growing tree for Turkey. Proceedings of the IUFRO Meeting on Management of Fast Growing Plantations, September 11-13, 2002, Izmit, Turkey, pp: 192-202
7: Cicek, E., 2004. Characteristics of forested wetlands and forested wetlands in Turkey. Orman Fak. Derg. Seri B, 52: 107-114.
8: Cicek, E., 2006. Various growth properties of elm (Ulmus laevis Pall.) under ash (Fraxinus angustifolia Vahl.) canopy. A.B.U. Ormanclk Derg., 2: 43-52.
9: Cicek, E. and M. Yilmaz, 2006. Effect of seedbed density on morphological characteristics and field performance of Ulmus laevis seedlings. J. Balk. Ecol., 9: 167-173.
10: Cicek, E., F. Tilki and N. Cicek, 2006. Field performance of narrow-leaved ash (Fraxinus angustifolia Vahl.) rooted cuttings and seedlings. J. Boil. Sci., 6: 750-753.
CrossRef | Direct Link |
11: Cicek, E., N. Cicek and N. Bilir, 2007. Effects of seedbed density on one-year-old Fraxinus angustifolia seedling characteristics and outplanting performance. New For., 33: 81-91.
CrossRef | Direct Link |
12: Davis, P.H., 1982. Flora of Turkey and the East Aegean Islands. Vol. 7, University Press, Edinburgh, pp: 386-387
13: Davis, P.H., 1997. Flora of Turkey and the East Aegean Islands. Vol. 6, Univ. Press, Edinburgh
14: Efe, A. and C.U. Alptekin, 1989. An important bottomland forest in Turkey: Haciosman. I.U. Orman Fak. Derg, Seri A, 39: 164-171.
15: Eriksson, G., 2001. Conservation of noble hardwoods in Europe. Can. J. For. Res., 31: 577-587.
16: Fraxigen, 2005. Ash species in Europe: Biological characteristics and practical guidelines for sustainable use. A Summary of Findings from the Fraxigen Project EU Project EVKCT00108. Oxford Forestry Institute, University of Oxford, UK.
17: Kapucu, F., H. Yavuz and A.U. Gul, 1999. Stem volume, site index and yield table in Fraxinus stands (In Turkish). KTU Research Project No. 96.113.001.4, Trabzon.
18: Kelty, M.J., 1992. Comparative Productivity of Monoculture and Mixed-species Stands. In: The Ecology and Silviculture of Mixed-species Forests, Kelty, M.J., B.C. Larson and C.D. Oliver (Eds.). Kluwer Academic Publishing, London, pp: 125-141
19: Kerr, G. and C. Cahalan, 2004. A review of site factors affecting the early growth of ash (Fraxinus excelsior L.). For. Ecol. Manage., 188: 225-234.
Direct Link |
20: Mayer, H. and H. Aksoy, 1998. Turkiye Ormanlari. Western Blacksea Forestry Res. Inst., Bolu, Turkey
21: Savill, P., 1992. The Silviculture of Trees Used in British Forestry. Cab International, UK
22: Smith, D.M., B.C. Larson, J.M. Kelty and P.M.S. Ashton, 1996. The Practice of Silviculture: Applied Forest Ecology. 9th Edn., John Wiley and Sons, Inc., New York