Variation among poplar clones for growth and crown traits under field conditions at two sites of North-western India

We evaluated the growth and crown traits of 36 poplar clones at two distinct agro-climatic regions of Punjab (Ludhiana and Bathinda) in northwestern India, following randomized block design with three replications and plot size of four trees. Significant differences among clones (p<0.001) were observed for diameter at breast height (DBH), tree height, volume, crown width and number of branches under both the site conditions. Clones ’G-3’, ’25-N’ and ’41-N’ at Ludhiana and ’G-3’, ’RD-01’ and ’S 7 C 8 ’ at Bathinda were found to be superior for volume production. All growth and crown traits registered significantly higher values at Ludhiana in comparison to those at Bathinda. Clone × site interaction was also significant (p<0.001). For volume, clones ’L-62/84’, ’113520’, ’25-N’ and ’S 4 C 2 ’ witnessed huge fluctuations in ranking between sites. The correlations between growth traits were positive and highly significant (p<0.001) at both sites. The clonal mean heritability was moderate for DBH and volume both at Ludhiana (0.61 0.66) and Bathinda (0.61 0.62). Across sites, the genetic advance was the highest for volume (49.76%) and the lowest (6.50%) in case of height.     

End-use related physical and mechanical properties of selected fast-growing poplar hybrids (Populus trichocarpa × P. deltoides)

This study focused on physical and mechanical properties of fast-growing poplar clones in relation to potential end uses with high added value. A total of 14 trees from three different clones, all P. trichocarpa × deltoides (T×D) hybrids, were felled in a poplar plantation in Lille (Belgium): six ‘Beaupré’, four ‘Hazendans’ and four ‘Hoogvorst’. Growth rate was found to have no significant influence on the physical mechanical properties. Although the investigated clones are genetically closely related, important variations in physical and mechanical properties were observed. Specific features such as spatial distribution of tension wood and dimensional stability are the main quality factors. It was concluded that ‘Beaupré’ is suitable for a wide range of high value added applications, such as plywood or construction wood. ‘Hazendans’ and ‘Hoogvorst’ will need adapted technology in processing. Further research is needed to characterize clonally induced variation in properties and to assess adequate processing strategies for multiclonal poplar stands.     

Variation of wood density and hydraulic properties of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) clones related to a heat and drought wave in France

Drought response of three Douglas-fir clones (slow, intermediate and fast growing) inhabiting two different climatic regimes in France was examined. We used the hydraulic conductivity and the percent loss of conductivity due to embolism from stems and branches as well as wood microdensity measurements to determine the role of genetics in the control of embolism in this species. Conductivity and tree-ring’s microdensity variables (ring width: RW, mean ring density: MRD, minimum ring density: MID and maximum ring density: MAD) were compared in growth rings in all three clones during a typical year (2002) vs. an extremely dry year (2003). A new method was developed in order to assess axial hydraulic specific conductivity (K_s) within tree rings. The results show that branches are more resistant to embolism than stems, and that there are significant differences in embolism resistance among the clones between the two sites. K_s varied between years, sites and clones but the site exerted the most significant effect. Lartimache (more humid site during 2003) trees showed substantially higher K_s than those inhabiting Chassenoix (strongly affected by the 2003 heat and drought wave site). Wood analysis showed a significant year effect for all ring variables and a significant clone effect for all ring variables except for MAD, while the site effect was significant for MRD and MAD. The existence of a genetic control for the study traits indicates that Douglas-fir populations introduced in France may have a selection potential to face extreme climate events like the 2003 heat and drought wave.     

The distribution of Phratora vulgatissima (Coleoptera: Chrysomelidae) on cultivated willows in Britain and Ireland

Insect samples were collected from the canopy of 24 willow short rotation coppice (SRC) sites on farmland in Britain and Ireland in 1995. The blue willow beetle Phratora (= Phyllodecta) vulgatissima (L.) (Coleoptera: Chrysomelidae), previously identified as the main defoliating pest of this crop, was recorded from 13 of these at varying levels of abundance. Data describing aspects of the environment at each site were also collected. These data were used to create potential explanatory variables for a regression analysis of beetle abundance. This analysis indicated that P. vulgatissima were most likely to occur and were more abundant at older willow sites on clay soils and at sites that bad certain free-living willow species growing nearby. Within sites, most willow clones sampled contained P. vulgatissima, although two, Salix burjatica‘Germany’ (‘Aquatica Gigantea’) and Salix mollissima‘Q83’ (Salix triandra × Salix viminalis), were avoided. Chrysomelid pest avoidance and clonal resistance could form part of an integrated pest management strategy for SRC crops.     

Genotype × environment interaction and growth stability of several elm clones resistant to Dutch elm disease

Conventionally hybrid elm clones obtained within breeding programs for Dutch elm disease (DED) resistance were selected to meet requirements for use as ornamentals. However, it has been long and commonly observed that these clones may show hybrid vigour and enhanced growth. Nowadays DED resistant hybrid elm clones, which have been released to the market or are under evaluation for an upcoming release, are numerous enough to be considered for timber production or short rotation coppice (SRC). But experimental testing of the growth performances of these clones in different environments is still lacking. In this paper, growth and stability of performance of 24 DED resistant hybrid elm clones planted at three experimental sites with contrasting environmental conditions in Italy were studied. Height and diameter were measured yearly from 2001 to 2009, and the mean yearly increments after plant establishment were calculated. The study revealed a general good growth performance of the majority of the clones with mean height increments above 1 m/year, and an excellent growth performance of some genotypes. Analysis of variance showed significant effects of clone, site and clone × site interaction, for both height and diameter increments. Stability analysis of diameter and height increments was performed by using two parametric (CV% and W²) and two non-parametric (Hühn's S_i⁽¹⁾ and S_i⁽²⁾) indexes. According to all indexes, two clones showed superior and stable growth. These clones may be suitable for planting in a range of environments. In addition, several other clones had high growth in general or at a particular site. The results support our belief that these elm clones could be successfully used for timber and biomass production, and provide new knowledge for an informed choice of the most suitable genotypes.     

An assessment of potential of hybrid poplar for planting in the Virginia Piedmont

Poplar species grow well across the temperate zone, but hybrid varieties have not previously been evaluated for planting in the Virginia Piedmont region. The top 12 clones in height growth and rust resistance from a screening trial involving 98 hybrid poplar varieties of three taxa (Populus deltoides × P. maximowiczii, DxM; P. deltoides × P. nigra, DxN; P. deltoides × P. trichocarpa, DxT) were selected for planting in replicated yield trials at two locations in the Virginia Piedmont. Results through the first four growing seasons showed that the DxM taxon had the most rapid height development. It was, however, the taxon most affected by a late spring frost at the Appomattox-Buckingham State Forest site and by Septoria stem canker at the Reynolds Homestead site. Analysis of variance of clonal and location effects showed highly significant differences among replicates within location and among clones within taxon. Among seven clones within the DxM taxon, pairwise comparison tests of height growth identified two groups: a group of four better clones that were significantly different (p = 0.05) from a second group of three. These early results suggest that multi-selection criteria, including growth, disease and frost resistance, are important when developing hybrid poplar clones for planting in the Piedmont region.     

萧氏松茎象发生与湿地松林地枯落物及土壤物理性质的关系

对萧氏松茎象不同危害程度湿地松林地的枯落物及土壤物理性质比较研究结果表明:枯落物及腐殖质层厚度对萧氏松茎象危害程度的影响最大,其次是枯枝落叶干质量和土壤含水量,枯枝落叶含水率和吸水率影响最小,即枯落物及腐殖质层越厚,枯枝落叶越多,土壤湿度越大的林区,萧氏松茎象发生越重。单因素分析表明:枯落物及腐殖质层厚度、枯枝落叶干质量和土壤质量湿度与有虫株率的相关关系均达到显著水平。萧氏松茎象有虫株率火炬松和马尾松林发生林地明显低于湿地松发生林地。与不发生林地相比,发生林地的土壤更湿润,土壤的保水能力更好,孔隙度更高,石砾含量相对较低。     

Susceptibility of provenances and families of Pinus maximinoi and Pinus tecunumanii to frost in South Africa

The future of South Africa’s most important pine species, Pinus patula, is threatened by the pitch canker fungus, Fusarium circinatum. Pinus maximinoi and P. tecunumanii represent two subtropical species that provide an alternative to planting P. patula on the warmer sites of South Africa. Extending the planting range of P. tecunumanii and P. maximinoi to include higher and colder altitude sites will reduce the area planted to P. patula and the risk of F. circinatum. During 2007 progeny trials of P. tecunumanii and P. maximinoi were planted on a sub-tropical and sub-temperate site. Shortly after the establishment of these trials, unusually cold weather conditions were experienced across South Africa (?3°C at the sub-temperate site) resulting in severe mortality. This provided the opportunity to assess the variation in survival as a measure of frost tolerance within these two species to determine whether it could be improved upon through selection. Results indicated that the variation in survival was under genetic control in P. tecunumanii (h _(0,1) ²  = 0.16, h _L ²  = 0.27) and P. maximinoi (h _(0,1) ²  = 0.11, h _L ²  = 0.23) at the sub-temperate site. Correlations in provenance ranking for survival across sites were high for both species. Moderate correlations in family survival for P. tecunumanii (r = 0.52) were found at the two sites. Improvements in cold tolerance can thus be made in both species extending their planting range to include greater areas planted to P. patula thereby limiting the risk of F. circinatum.     

Importance of Site Type and Tree Species on Disease Incidence of Gremmeniella abietina in Areas with a Harsh Climate in Northern Sweden

The importance of site type and tree species on disease incidence of Gremmeniella abietina was investigated. Blocks of four conventional regenerations of Pinus contorta and Pinus sylvestris, situated on sites formerly supporting pure stands of P. sylvestris and Picea abies respectively, were examined for the occurrence of G. abietina. Trees planted on spruce sites were found to be more severely diseased by G. abietina than trees planted on pine sites. Pinus contorta was more severely attacked by G. abietina than P. sylvestris on both site types. The results show that plantations of P. contorta and P. sylvestris in areas originally covered with pure spruce forests run a high risk of damage by G. abietina.     

Inter‐ and intraspecific variation and genotype × site interaction in Salix Alba L., S. Dasyclados Wimm. and S. viminalis L.

Three test series were planted on sites selected for their contrasting properties to study the genotype × site interaction. Various clones of Salix alba (8 clones in the 1980 series), S. dasyclados (8 clones in 1982 series) and S. viminalis (6, 9, 13 clones in the various series) were included. Growth capacity, survival and infection by rust fungi were analysed. Interspecific variation was seen at some of the sites in the 1982 series but it was pronounced in the 1980 series where 5. viminalis outgrew 5. alba at all sites. Intraspecific variation could be seen for growth capacity, survival and rust resistance. A genotype × site interaction was detected for all variables studied. Some of the interaction, especially at the species level, can be explained by the variation in susceptibility to rust fungi and preference for soil types. In the breeding work with Salix the genotype × site interaction must be considered.     

Effects of soil preparation methods and plant types on the establishment of poplars on forest land

Key message

The success of poplar plantations on forest land was affected by soil preparation, plant type, site, and clone. Mounding in combination with large plant types (rooted plants or long cuttings) of site-adapted clones achieved the highest survival and growth.

Context

Poplars (Populus species and hybrids) are fast-growing trees used to make various products. In north European countries, they are mainly grown on agricultural land, but interest in planting poplars on forest land has increased.

Aims

Plant damage and mortality problems occur on forest land, probably due to soil conditions and competing vegetation. It is therefore of interest to investigate whether combinations of soil preparation methods and plant materials can improve establishment.

Methods

At three sites in southern Sweden, the effects of four soil preparation treatments (no soil preparation, patch scarification, mounding, soil inversion) in combination with three plant types (short cuttings, long cuttings, rooted plants) were studied.

Results

Survival and growth were significantly influenced by site, soil preparation method, plant type, and their interactions. Mounding resulted in the best overall performance on all sites. Interactions between site and plant type revealed differences in growth dependent on site conditions, but rooted plants and long cuttings were in general most successful. Patch scarification and short cuttings were associated with lower survival and growth.

Conclusion

Soil preparation is needed to support survival and early growth, but the combination of method and plant type must be adapted to site conditions. The choice of clones should also be considered.

     

Grouping of <Emphasis Type="Italic">Tectona grandis</Emphasis> (L.f.) clones using wood color and stiffness

Commercial Tectona grandis plantations using clones have attracted considerable interest for lumber production in tropical regions where small areas are frequent. However, studies on wood properties are limited. Therefore, the purpose of this study is to group clones with similar wood color characteristics using the CIELab system, and mechanical resistance by dynamic stiffness (Ed) in order to obtain different types of clones for different climate and edaphic conditions. It was found that lightness (L*), yellowness (b*), redness (a*), and Ed are similar to those found for other plantation trees. These wood characteristics are significantly influenced by clone and site. Variance due to clone and site went from 31 to 53% and from 2.95 to 24.22%, respectively. Another source of variance was distance from pith, with the exception of parameter b*, which was not affected. Finally, clones were grouped (using multivariate analysis) according to color and mechanical resistance. This analysis established 4 groups by color and 5 groups by Ed. Clone clustering will allow us to choose or use clones with similar wood properties according to site and environmental conditions increasing area production and wood quality uniformity.     

Spatial distribution of late-successional coniferous species regeneration following disturbance in southwestern Québec boreal forest

Remnant tree stands left intact following a disturbance constitute the sole seed banks available for regeneration of coniferous species that neither bear serotinous cones nor reproduce vegetatively. The success of regeneration of tree species on these disturbed sites is, therefore, dependent on the distance from potential seed sources. The regeneration of balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss) and white cedar (Thuja occidentalis L.) was studied at two sites in Québec’s southwestern boreal forest in order to quantify the influence of remnant stands on spatial distribution of regeneration. The first site is located in an area that burned in 1944 while the second site is located in an area that was clear-cut in the mid-1980s. Canonical correspondence analyses were used to determine the respective contributions of environmental data and spatial variables to the pattern of spatial distribution of regeneration. The results reveal that distance from a remnant stand is the most important variable in explaining spatial distribution of regeneration when compared to environmental variables such as soil type, drainage, slope and altitude. The plots of regeneration density against distance from a remnant stand for both the burned site and logged site show that regeneration density decreases abruptly with distance from a remnant stand. Furthermore, spatial autocorrelation analyses (Moran’s I) indicate that even small remnant zones can significantly influence the pattern of spatial distribution of regeneration for the three species studied. The results presented here suggest that where preestablished regeneration is not abundant enough, alternative silvicultural systems such as strip clear-cutting or seed-tree systems could be used instead of cuts with protection of regeneration and soils (CPRS).     

Relationships between climate and tree radial growth in interior British Columbia,Canada

Climate is a main driving factor of the formation of annual tree-rings, but which climatic variables are the most influential on radial growth may vary among species and sites. To explore these interactions, tree-ring chronologies along a major elevation gradient were examined for three tree species in southern interior British Columbia (Canada): Pseudotsuga menziesii, Pinus contorta, and Picea glauca × engelmannii. We used correlations and linear and multiple regressions to explore the relationships between tree-ring radial growth and climate variables in the area from 1922 to 1997. All correlation coefficients between ring chronologies and monthly climatic variables were medium to low (from −0.3 to 0.4); nevertheless, moderate but significant trends could be identified. Multivariate models explained up to 53%, 43% and 32% of radial growth variability for P. contorta, P. menziesii and P. glauca × engelmannii, respectively. All three species showed similar radial growth–climate patterns across the elevational gradient, but they had different details that made ring width–climate relationships species-specific. Precipitation-related variables were more related to radial growth at low-elevations, changing into temperature-related variables at high-elevations. Tree-ring width for all three species was primarily and significantly affected by climate variables from the year previous to the growing season and only secondly by current year conditions, but the critical months varied for different species and altitudes. Winter precipitation also affected radial growth, either as a source of water or as a possible agent of physical damage. Although our work showed significant climate influences on breast height tree radial growth, our results also indicated that other site factors such as microclimate or stand dynamics can be as or more important than climate variability.     

Growing clonal mixtures of willow to reduce effect of Melampsora epitea var. epitea

Rust (Melampsora epitea var. epitea) is the single most limiting factor in the production of biomass from short rotation coppice willow. The use of fungicides is unacceptable for economic, environmental and practical reasons. Consequently, clonal mixtures were investigated as an alternative disease control strategy. At one of two sites Salix × dasyclados, Salix burjatica ‘Korso', S. burjatica‘Germany’, Salix viminalis‘Bowles Hybrid’ and S. viminalis‘683’ were included in the clonal mix. At the second site six clones were used. These were as above with the exception of S. burjatica‘Korso’ and including, Salix × calodendron, Salix mollissima-undulata‘SQ83’. At both sites all clones were also planted in monoclonal stands. Throughout each growing season disease levels were recorded on individual clones, both in monoclonal stands and mixtures. Fungicide treatments were included to compare their effectiveness to mixtures in reducing disease impact. Growing willow in mixed clonal stands delayed the onset of disease, slowed its build up and resulted in lower disease levels at the end of the growing season. These reductions in disease impact contributed to the increased yields obtained from clonal mixtures and were generally comparable to those achieved with fungicides.     

Frost damage to planted Norway spruce seedlings — influence of site preparation and seedling type

Damage to Norway spruce (Picea abies (L.) Karst.) seedlings by summer frost was monitored on 10 clear-cuttings of various ages to which slash removal and four types of site preparation had been applied. The clear-cuttings were established on two sites (5 on each) in southern Sweden from 1989 through 1993 and planted each year from the year of cutting until 1993. In total, 7680 seedlings were analysed for frost injuries during the first three years following planting. The site preparation methods evaluated were: application of herbicide to ground vegetation; mowing of ground vegetation; scarification (mounding); and control. Two seedling types, bare-rooted and containerised seedlings, were evaluated.Periods of frost susceptibility were calculated using data on bud and shoot development during 1997 together with weather data for each of the studied years and sites. The date of flushing was well correlated to the air temperature sum (+5°C threshold value) in spring. Frost damage varied considerably between sites and study years. The lowest measured minimum air temperature and the frost-day sum during the frost-susceptible period were correlated to the frequency of frost damage. Soil scarification reduced frost damage in the first growing season. Bare-rooted seedlings had a considerably lower frequency of frost injury compared with containerised ones, possibly because flushing of the former was delayed. There was no statistically significant effect of herbicide application, mowing or slash removal on the frequency of frost damage. Seedling growth was significantly reduced by frost injury, especially in cases where injuries were sustained during several years. Survival was only slightly affected by frost damage.     

Adaptation and morpho-physiology of three Populus deltoides Marsh.?×?P. nigra L. clones after preconditioning to prolonged waterlogging

The implementation of a management-protection program, using suitable cultivation practices, contributes to rehabilitating marginal areas prone to prolonged waterlogging and preserving biodiversity. Three hybrid poplar clones (‘I-488’, ‘Rimini’ and ‘D-64’) were tested to assess their degree of tolerance to waterlogging by imposing four water regimes over a 1?year period: control (C), non-preconditioned (NPr), and two levels of flood preconditioning (Pr₁₀ and Pr₂₀). During the 2nd?year, waterlogging (1.9?±?0.7?mg/l O₂) was imposed on plants from NPr, Pr₁₀ and Pr₂₀ treatments for 60?days followed by drainage. Survival rate, dry mass production, net photosynthesis and relative damage to membrane structural integrity were evaluated. The treatment response varied among clones and levels of preconditioning. Less pronounced damage to ‘I-488’ clones in comparison to those of ‘Rimini’ and ‘D-64’ indicates its superior tolerance to waterlogging. Preconditioning treatments (Pr₂₀) and, to a lesser extent (Pr₁₀), significantly improved the ability of the clones to tolerate flooding, suggesting that the application of a Pr₂₀ preconditioning treatment in the nursery before outplanting would give hybrid poplar clones the morpho-physiological advantages necessary to counteract the arduous conditions on inundated sites.     

Future outlook for Pinus patula in South Africa in the presence of the pitch canker fungus (Fusarium circinatum)

Approximately 50% of the area planted to softwood trees in South Africa has been established with Pinus patula, making it the most important pine species in the country. More effort has gone into developing this species for improved growth, tree form and wood properties than with any other species. This substantial investment has been threatened in the last 10 years by the pitch canker fungus, Fusarium circinatum. The fungus infects and contaminates nursery plants and, once transferred to the field, causes severe mortality of young trees in the first year after establishment. Although nurserymen have some control of the disease, it is recognised that the best long-term solution to mitigate damage because of F. circinatum infection is to identify tolerant species, clones and hybrids for deployment in plantations in the future. Research has shown that alternative species such as P. tecunumanii, P. maximinoi and P. elliottii are suitable for warm sites. Pine hybrids, particularly between P. patula and the high-elevation sources of P. tecunumanii, appear to be a suitable replacement on subtemperate and temperate sites. Although these alternative species and hybrids are more sensitive to subfreezing temperatures than P. patula, their planting range can be increased by including cold tolerance as a selection criterion. Future breeding efforts will most certainly focus on improving the tolerance of pure P. patula to F. circinatum, which can be achieved by identifying specific family crosses and tolerant clones. The commercial deployment of disease-tolerant control-pollinated P. patula and hybrid families will most likely be established as rooted cuttings, which requires more advanced propagation technology. In the long term, new seed orchards comprised of P. patula clones tolerant to F. circinatum could be used to produce seed for seedling production.     

Clonal stability in <Emphasis Type="Italic">Pinus radiata</Emphasis> across New Zealand and Australia. I. Growth and form traits

To investigate genotype by environment interaction (G×E) for clones of radiata pine (Pinus radiata), clonal stability was evaluated for growth and form traits from three trials in New Zealand and three trials in Australia. There were 215–245 clones in common between pairs of New Zealand trials, 17–26 clones in common among Australian trials, while 32–52 clones were in common between New Zealand and Australian sites. Clonal repeatability ( [^(H)]² ) \left( {\hat{H}^{2} } \right) and type-B genetic correlations were estimated. The general trend across the six trials for clonal repeatability was that [^(H)]² \hat{H}^{2} was greatest for height (HGT) followed by diameter at breast height (DBH), stem straightness (STR), and branch quality score (BRQ). Within New Zealand trials, there was little evidence of G×E for growth traits, but more for form traits. For DBH the average type-B genetic correlation within New Zealand was 0.82; and for HGT, the average type-B genetic correlation within New Zealand was 0.76. Within Australia, there was only one statistically significant type-B genetic correlation for DBH and this estimate was high indicating that clonal ranks were similar on these two trials. Additionally, within Australia and between regions type-B genetic correlations were generally high for form traits, at least for STR. One Australian trial (Trial 5) showed relatively high clonal stability with the three trials in New Zealand indicating that the ranks of these clones were relatively stable in both regions. From a clonal testing standpoint, these results suggest that stable clones can be identified that perform well in both New Zealand and Australia. Improvements in both growth and form traits can be expected when radiata pine clones are transferred between Australia and New Zealand within regions similar to those sampled in this trial series.     

Genotypic parameters of wood density and fiber traits in triploid hybrid clones of Populus tomentosa at five clonal trials

? Context

A clear understanding of the genetic control of wood properties is a prerequisite for breeding for higher wood quality in Populus tomentosa Carr. hybrid clones.

? Aims

The experiments aimed at unraveling genetic and environmental effects on wood properties among triploid hybrid clones of P. tomentosa.

? Methods

We used 5-year-old clonal trials established in Northern China to assess the heritability of wood density and fiber traits. Two hundred seventy trees from nine clones were sampled in five sites.

? Results

Site had a very significant effect on all recorded traits. Despite this large site effect, a tight genetic control was detected and clonal repeatability varied between 0.53 and 0.95. Significant genotype?×?environment interactions were detected for most of the traits. Moderate to tight correlation were evidenced among traits but they were not consistent with that in several cases that were site-dependent.

? Conclusions

Our results revealed a tight genetic control over several wood properties and therefore breeding programs might be able to improve wood density, fiber length, and coarseness in these hybrids.