FAIR-CT97-3354 Towards a European larch wood chain

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FAIR Area 1.3 - Forestry-Wood Chain : Solid Wood Products : Wood (Lignocellulose)

	Contract No:	FAIR-CT97-3354
	Date Prepared:	September 2000
	Source:	Second Annual Progress Report Abstract

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Second Annual Progress Report Abstract

Introduction

This project is motivated by several factors that appear to limit development of larch plantations across Europe. The quality of larch wood from fast-growing lowland plantations is not known. Compared to native alpine larch with slow growth, it might be expected that its major properties would be altered. The volume of this lowland resource is becoming more and more important. On the other hand, the traditional larch timber market (native range) is suffering actual shortages. Out of its native range, larch stands based on faster growing species and varieties have been, in many cases, poorly managed resulting in sub-optimal yields and wood quality. As the result of several silvicultural advantages, foresters favour larch in many places across Europe and are ready to extend plantations. Nevertheless, shortages of improved varieties and of plantlets impede reforestation plans.

Objectives

Therefore, the objectives are clear:

• to develop knowledge on wood quality of the lowland larch timber resource mostly for its most original and economically important properties : natural durability and mechanical strength
• to prepare silvicultural guidelines and stand management scenarios allowing combination of maximum timber production, high wood quality and respect of environmental issues
• to select new improved varieties (for growth, architecture, wood quality and resistance to pests) and to improve efficiency of creation and selection tools
• to develop and optimise techniques for mass-production of reforestation material either by generative (seed) or by vegetative (cutting) propagation systems.

To reach these objectives, a scientific as well as a technical approach is needed. Expertise in many scientific fields including wood technology, silviculture, ecology, genetics and breeding, physiology, etc. was requested and has been found in several Research Institutes across EU. Geographic susceptibility and constraints are therefore better integrated. As well, involvement of several industrials was needed for an easier transfer of scientific results into practical applications.

Activities

Research work includes a comparison of larch wood quality from the new lowland timber resource with the traditional native alpine resource adopting technological, as well as a laboratory, approach on a large and unique wood sample. The technological appreciation relies on 3 types of end-products, solid plain wood beams, laminated glued beams and floor parquet. Laboratory investigations are concentrating on 2 main properties, natural durability and mechanical strength. Anatomy, wood chemistry, microdensitometry and later many other parameters (shrinkage, Young's modulus, etc) are studied and will be related to technological results. This will for the basis for eventual study of alterations of wood properties.

In order to prepare guidelines for establishment of larch stands (pure or mixed), have been started:

the creation of a database with all available base reproductive material across EU

• the establishment across EU of a progeny trial network for evaluation of major hybrid varieties
• the analysis and synthesis of information from nursery plantlets handling trials and field establishment experiments as well as from planting audit
• the plantation of demonstration plots (with new varieties, mixtures, etc),

In addition, in order to produce several scenarios for larch stands management, growth parameters are being studied both in field experiments, in permanent/semi-permanent plots in the forest or from stem analysis. Impact of thinning on stand features will be assessed including both yield and external (straightness, branching, etc) and internal (heartwood proportion) quality aspects. Growth models are built both for pure (even-aged) and mixed (with beech) stands. Impact of larch stands features and of thinning intensity on biodiversity (undergrowth vegetation and underground fauna) is investigated through modelling of light under canopy. Several silvicultural scenarios combining yield, wood quality and biodiversity aspects will be further built.

Results from tree breeding programmes (developed separately in most countries) will be exploited mostly with the intent to select a much broader set of genetically diverse and highly performance varieties of hybrid larch. Creation and selection tools are investigated to optimise their efficiency. Demonstration of hybrid vigour and understanding of its genetic determinism is focused on. Development of prediction tools of hybrid vigour (quantitative parameters as well as QTL search) is needed to rationalise future creation of hybrid material. Tools (molecular and morphological markers) for hybrid and parents identification are developed. Three selection criteria (stem form, non-destructive parameters of wood quality, pest resistance - Lachnellulla and Fomes) are revisited to ascertain their genetic parameters (level of variability, of their genetic control, their relationships with other traits, etc) and possibilities for early selection. Long-term breeding relies also on proper management and conservation of major European larch populations from Central Europe : a European-wide network of experiments (progeny trials) will be established from new seed collection ; older trials are under analysis for genetic variability assessment which will be completed through isozyme analysis.

For creation and mass-production of varieties in seed orchards, all steps leading to maximum full seed production and optimal seed use is being investigated: from flower induction (mechanical, chemical, control of rootstock, control of environment) and pollination (management of pollen and pollination technique) to seed extraction (screening of methodology and refinement), conservation and control of dormancy and seed pre-treatment.

Optimisation of all steps in the vegetative propagation process by cutting is looked at; from management and selection of rootstocks, to rooting conditions and proper handling of rooted plantlets later in the nursery benches. Production in a pre-commercial stage will be attempted as well as an economical validation. Demonstration plots will be planted , they also include plantlets from somatic embryogenesis.

Progress

After the first year period during which material and protocol have been exchanged, experimentation has been initiated for all four tasks. First results have been produced but in most cases, they are still at this stage too much preliminary for full, or even partial, presentation.

Task 1. For task 1, the first year and a major part of the second have been spent to the harvesting and sampling of a unique collection of trees : nearly 350 trees from 13 different genetic origins, collected in 6 stands across EU (A, B, D, F, GB). Part of the material (343 logs) has been prepared for scientific investigation and shared among participants, part of the material (over 160 m 3) has been sawn into boards or beams and shared among the 3 industrial partners for further processing and evaluation. Nearly half of the laboratory samples have been investigated by biological test for decay resistance to fungi and for anatomical and physical (microdensitometry) properties. About 20 % have been chemically analysed for extractives in relation with natural durability.

Most of the third year will be spent on the continuation of these analysis, the beginning of mechanical tests and the exchange of data and their analysis. On the industrial side, processing into laminated beams and floor parquet will be done together with evaluation of end-products. Task meetings took place in December 1999 and 2000 in Vienna.

Task 2: Progress in building the database of reproductive material has been a bit delayed, but during the last annual meeting in Gembloux, agreements have been obtained from all participants on its goals, structure and software. Evaluation of hybrid varieties is underway either through existing trials (hybrid orchard varieties, comparison of cuttings vs seedling, etc) or through a new progeny trial network with hybridisation orchard varieties - For the latter, sowing has been done in all participating countries and the field establishment of the network will start this coming winter. The comparison study of cuttings and seedlings has much progressed and original results have been obtained on their root architecture.

A numerous set of additional data have been obtained and exchanged for growth modelling in pure stands. Analysis has started and site index curves found in Belgium for European and Japanese larch have been compared with published curves in Europe. A tree growth model has been constructed for thinned stands in Belgium and tested on French trials data. For growth modelling in mixed stands, the analysis of yield parameters and stand structure over years (from 40-160 yrs) is achieved and it clearly shows the advantage of mixed beech-larch stands compared to pure beech stands for total volume production at any ages. Modelling of diameter increment has been worked on and is based on 2 variables : crown-surface area and a competition index.

The best descriptor of light irradiance under canopy seems to be the stand basal area. Simple tables relating irradiance to basal area have been constructed at the intent of foresters. Larch appears to have at juvenile stage (up to 20 yrs old) a similar relationship curve between irradiance and basal area than douglas-fir but surprisingly lower than that of Norway spruce. Finally, an initial analysis of silvicultural scenarios which might be produced as a result of all this work is underway.

Task 3: The genetic diversity study is impeded by the delays in seed collection in the Sudetan Mountains and as a result, in the establishment of the progeny trial network. Nevertheless, measurements in existing trials are progressing, as is the isozyme analysis. The most significant results have been obtained in interspecific hybridisation, as well as in continued work on control crossings, measurements in existing trials and establishment of new FI/F2 hybrid progeny trials. In particular:

• the evidence of heterosis has been demonstrated for the first time for growth and phenology
• the clarification of the parental species influence on the genetic control of performances in hybrids, some traits are under strong genetic control of the European larch (wood quality) , some of the Japanese larch (architecture) or of both (growth)
• prediction of hybrid performance seems possible from quantitative genetics parameters
• several QTL for wood quality and growth traits have been found and open new prospects for marker-assisted-selection
• molecular tools (cytoplasmic markers and isozymes) for hybrid identification are right now available and their fields of application is very wide in control of genetic quality of hybrid orchards varieties (purity), in breeding and in the control of identity for numerous studies
• morphological studies have begun and will complete the approach with testing possibilities of sorting plants in the nursery.

Work has also progressed in measurements and/or observations of wood quality traits on a broad set of genetic entries. Once results will be ascertained concerning their genetic control, their relationship with growth traits, and the stability of genotypes over site and time, they will be much useful for improving selection process in breeding and for evaluating the efficiency of selection in correcting or reaching key quality levels defined by task 1. Evaluation of risks of sensitivity of larch to butt and root rot is underway as well as the improvement of the reliability of artificial inoculation test with larch canker.

Task 4: For generative propagation, several results have already been obtained along the generative chain, namely:

• First results from artificial flower induction are now available : the interest of girdling + gibberellins combination is confirmed for induction in both European and Japanese larch. Nevertheless, all the results found by the different partners do not go in the same direction. It is to be feared that the effectiveness of the treatments depends on the clone ; that would make the task of seed orchard managers and larch breeders more complicated. New experimentation will be carried on.
• A pilot-seed production in hybridisation orchards using supplemental pollination has given significant economical and scientific results on the best technique for pollen collection, pollen yield, time and cost for the different pollen manipulations, pollen consumption, time for pollination, etc. Some improvements are still possible and will be tested (e.g. pollination techniques).
• Water activity does not seem efficient to evaluate pollen viability.
• Efficiency of different techniques of seed extraction out of cones has been tested and a survey of seed extraction equipment and techniques used in European countries has been completed. A prototype inspired by the best techniques has been designed and will be tested.
• In French conditions, maturation of European larch cones seems to be attained as early as mid- August. Post-maturation treatments have no effects on germination. No problem of dormancy has been noticed so far but must be tested on stored seed.
• Floatation of seeds in alcohol did not lead to complete separation of full and empty seeds. Further investigations are needed in that field, Germinable seed can still be recovered from seedlots cold- stored all along the last 40 years. 8

For mass-propagation by cuttings, results continue to accumulate in

• Determination of the best period for insertion of cuttings : it seems to vary from country to country
• Relationship between stock plant phenology and stockplant nutrition on rooting ability. Rootability markers such as adventitious rooting seem disappointing. Addition of fertiliser on stockplants can result in a massive increase in fascicle shoot growth.
• Maturation effect of stockplant on rootability has been once again demonstrated as well as the clonal instability of rooting over years or seasons of cutting insertion.
• Assessment of combined effects of transplantation date and root pruning, of container type and of rooting environment, on rooted cuttings,
• The development of a software application for appraising the economic viability of plant production by cutting

Finally, although a very large number of new zygotic embryos have been introduced in culture this year, only 22 different lines have been obtained so far from somatic embryogenesis. Moreover only 9 have proved to be hybrids. Causes for this low hybrid proportion will be investigated.

One cell line has been exchanged.