Coppices: determinisms of sprouting and production

Transcription

1 Coppices: determinisms of sprouting and production Nicolas MARRON Yves EHRHART Éric LACOMBE Francis COLIN EPIC_IUFRO - September 15, Nancy

2 Introduction Epicormic shoots are known to decrease the log value But they are also the means by which trees regrow after coppicing or pollarding For these forestry techniques, high ability to produce epicormics shoots is an asset Some wood production systems are entirely based on these properties: coppices

3 Coppice definitions Short rotation forestry (SRF) to trees/ha Rotations from 7 to 10 years Goal: to produce multi-stem small trees (D = 15 cm, H = m) Forestry Short rotation coppice (SRC) Traditional coppice 60 to 300 trees/ha Rotations from 10 to 45 years Goal: to produce multi-stem small trees (D < 27.5 cm) Modern coppice to trees/ha Rotations from 2 to 3 years Goal: to produce many small resprouts (D = 3-4 cm, H = 4-6 m) Agriculture

4 Coppice species Traditional coppice Modern coppice (SRF / SRC) Pubescent oak Holm oak Chestnut Beech Sessile oak Pedunculate oak Southern species Northern species Eucalyptus Black locust Poplar Willow

5 Coppice objectives Traditional coppice Stakes Parquets Products Firewood Modern coppice (SRF / SRC) Pellets Paper Production objectives 5 to 20 m 3 ha -1 year -1 8 to 15 Mg DW -1 ha -1 year -1

6 Coppice limits Traditional coppice - Risks of soil impoverishment, in case of short rotations - Currently weakly profitable Modern coppice (SRF / SRC) - Not biodiverse / Bad impact on landscape - Declines due to pathogens : poplar rust, alder and chestnut Phytophtora, etc. Need to better understand the factors determining production and their relative importance

7 Production determinism Production (tons / ha) Chemicals Sludge Resprout dry biomass Number of resprouts Wastewater Planting density Genetic determinism Environmental determinism Fertilization Harvest calendar Interspecific variability Intraspecific variability Pedoclimatic conditions Plantation management Plantation design Cultural antecedent 1 st year coppicing

8 Interspecific variability Stem circumference (cm) Stem height (cm) 1 st year 1 st year 2 nd year 2 nd year One- / Two-year old trees Carbon isotope discrimination (, ) A A a b A A B B Leaves Wood Leaves Wood Leaves c Interesting potential of black locust as compared to poplar and willow, especially on marginal sites Poplar Dorskamp Robinia 2 provenances Willow 8 clones

9 Intraspecific variability Partners involved Location - Central France - Northern Italy Calendar - Plantation in Harvest: winter 2004 / Resprout counting: spring Heterosis (hybrid vigor) - Significant correlation between production and number of resprouts - But weak heritability Culture system - 2 families (DxN / DxT) genotypes each trees / ha - 2-year old trees Marron et al. 2010

10 Pedoclimatic conditions Two-year old trees Main stem dry weight (g) Clone * Site *** CxS ns Inger Jorr Tora Tordis Inger Tora Tordis Clump dry weight (g) Attigny Clone ns Site * CxS ns St Sulpice des Landes Production very variable between sites, even for quite close edaphic and climatic conditions! Inger Jorr Tora Tordis Inger Tora Tordis Attigny St Sulpice des Landes

11 Plantation management: Planting density Two-year old trees Height (m) 6 5 Circumference (cm) Competition among trees can rapidly compensate the gain 10due to more trees per hectare trees/ha 7200 trees/ha trees/ha 7200 trees/ha Toillon et al. 2013

12 Plantation management: Mineral fertilization Two-year old trees Second rotation Main stem height (cm) Clone *** Fertilization * CxF ns A B A Unfertilized Fertilized Unfertilized Fertilized Unfertilized Fertilized Number of stems Dorskamp Clone I214 Koster Fertilization ns CxF ns When soil is fertile enough, chemical fertilization can be detrimental because it benefits to weeds more than to trees 2 0 Unfertilized Fertilized Unfertilized Fertilized Unfertilized Fertilized Dorskamp I214 Koster

13 Plantation management: Sludge spreading Two-year old trees Tree growth was stimulated by the single sludge dose Number of stems However, the double dose was harmful for some of the clones Sludge spreading: - Spring 2011 Growth and sampling: - Summers 2011 / 2012

14 Plantation management: Wastewater spreading Two-year old trees 2000 Dry mass (g) of dominant stem and clump Stem Clump A A B AB B B Control Wastewater Whey Tree growth was stimulated by the wastewater and whey application However, this positive effect was counterbalanced by a much higher tree mortality where residues were spread

15 Plantation management: Harvest season Three- to four-year old trees Harvesting during spring (with leaves) or during fall (without leaves) had no effect on regrowth three years later

16 Plantation management: Clonal mixing Twelve-year old trees Number of stems Clone * Treatment ns CxT ns To.00 limit pest development, clonal mixing is generally 120 Clump dry weight (kg) Clone *** preferable but the impact on production Treatment is weak ns 100 Beaupré Bolaere Hunnegen Raspalje Triplo Cima Luisa Avanzo 80 CxT ns Beaupré Bolaere Hunnegen Raspalje Triplo Cima Luisa Avanzo

17 Plantation management: Cultural antecedent Two- / four-year old trees Tree height (cm) Installed 2008 Installed A C B B Amagne (grassland) Asfeld (grassland) Ambly-Fleury (maize) Semuy (maize) On similar cultural antecedents (maize = rich, grassland = less rich), tree performances can be similar as well as completely different

18 Plantation management: First year coppicing Partners involved Two-year vs. one-year old stems Main stem dry weight (g) Uncoppiced Coppiced Uncoppiced Coppiced Uncoppiced Coppiced Clump dry weight (g) Coppicing *** Clone *** CxC ** Inger Tora Tordis Coppicing *** Clone ** CxC ns Strikingly for clone Inger, because of multiple stems production after coppicing, total biomass was almost similar for one- and twoyear plants Location St-Sulpice-des- Landes (Loire Atlantique) Calendar Growth + phenology: Sampling: - Feb. Oct July Culture system clones 0 Uncoppiced Coppiced Uncoppiced Coppiced Uncoppiced Coppiced plant / ha Inger Tora Tordis - Installed in ha (LA) + 5 ha (V)

19 Interspecific variability Intraspecific variability Pedoclimatic conditions Plantation management Production determinism Most of the tested management options with minor effects on resprouting and production Substantial impact, with often high interactions with genotype, meaning clonal selection specific to site Very high, interspecific hybrids showing significant hybrid vigor High, dependent on site conditions Species choice must be adapted to local conditions

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