Regional scale simulation of the forest resources evolution in Southern Belgium (Wallonia)

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IUFRO 125TH_A_NNIVERSARY_C_ONGRESS 18 - 22 September 2017 – Freiburg, Germany 1 _{University of Liège}

Gembloux Agro-Bio Tech

Department of Biosystems Engineering

Regional scale simulation

of the forest resources evolution

in Southern Belgium (Wallonia)

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Developping methods and tools to :

1) Assess the current forest resources with accuracy 2) Study the likely outcome of changing forestry

3) Predict forest resources evolution

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Cover 1/3 of Wallonia :

 450 000 ha of productive forest stands ≈ 50 % public managed forest (DNF)

Small-scale intensive forest management :

 Highly fragmented forest

 Generally thinned every 6 to 12 years  Main harvesting method = clearcutting

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Undergoing transformation to deal with :

 Climate change and forest disturbances  New environmental regulations

 New economic opportunities

Question : What impact on wood industry supply?

 Need updated data and simulation tools

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Permanent Forest Inventory of Wallonia (FIW)

 Systematic sampling : 0.1 ha every 1000 * 500 m

Wallonia forest observation network

 11 000 PSP in forest land  ± 10 % monitored / yr  First monitoring : 1994-2008  Second in progress : ≈ 50% done

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Wallonia forest observation network

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 A better time resolution is required  Fast composition changes underway

Variation 2001 2012 (ha/yr) Norway spruce 167 000 141 000 -2 364 Douglas-fir 20 000 27 500 682 Other 26 000 24 000 -182 Total 212 500 192 500 -1 818 Oak 108 000 109 000 91 Beech 59 500 65 500 545 Other 71 500 81 500 909 Total 239 000 255 500 1 500 Species

Estimated area (ha)

So ft w oo d H ar d w oo d -15% +38% -9% +7%

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Method : updating FIW data

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FIW data were updated using aerial photographic cover :

Photo interpretation on PSP coordinates (11 079 plots) Working pace : ≈ 400 plots / hour  1 213 CC identified In example :

41 years spruce stand sampled in 1998

2006 2009

2015 2012

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Photo interpretation results analysis :

 Clearcut area ≈ 4 500 ha/yr (80% in softwood)  Clearcut probability = f(species, owner, age, SI)

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Reforestation survey in recent clearcuts (N = 529) :

 Total reforestation rate ≈ 92 %

 Reforested species in softwood stands :

 Low productivity softwood  hardwood

Method : updating FIW data

Other Larch

Douglas-fir N. Spruce

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Development of a forest simulation software :

 Integrated in the CAPSIS1_{platform (java)}

 From the tree level to the regional scale

First version fully functional (GYMNOS)

 For pure even-aged softwood stands

New version in development (SIMREG)

 Expansion to other species and structures

Method : simulating forest stands evolution

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Operating of GYMNOS

 Virtual stand creation from basic variables

 Nha, Age, Hdom, Cg, Stdev

 Integrate latest growth and allometric models

 Tree level distance independent

 Several thinning procedures available

 Type and intensity are perfectly configurable

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Operating of GYMNOS at the regional scale

INPUT = regional forest inventory data

 Each sampled plots  several virtuals stands

Forest management calibrated with 3 process :

Method : simulating forest stands evolution

40 30 20 10 0 3 2 1 0 -1 -2 -3 40 30 20 10 0 3 2 1 0 -1 -2 -3 40 30 20 10 0

1. Norway spruce; age < 40

Pe

rc

en

t

1. Norway spruce; age >= 40

2. Douglas fir; age < 40 2. Douglas fir; age >= 40

3. Larch; age < 40 3. Larch; age >= 40 Standing trees Thinned trees

Standardized natural logarithm of tree girth at breast height

N = 4 657 N = 6 146 N = 694 N = 239 N = 116 N = 278 Other Larch Douglas-fir N. Spruce

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Operating of GYMNOS at the regional scale

Performances

 200 000 ha for 50 years ≈ 90 min

 1.2 * 106_{annual tree growth /s}

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Simulation of Wallonia softwood evolution

2040 2030 2020 3000 2000 1000 0 Year N. spruce Douglas-fir J. larch Total yield (10³ m³) Total area (10³ ha)

2040 2030 2020 200 150 100 50 0 Year N. spruce Douglas-fir J. larch Clearcut

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Conclusions :

Unsustainable harvesting rate

 ≈ 1.2 * yield

Partially offset by high yield of douglas-fir

 DF yield ≈ 1.3 * NS yield

 Possible solution : ↗ douglas-fir reforestation

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Automatic detection of clearcuts :

 With Sentinel-1 and Sentinel-2 data

Improvement of the simulator :

 Expansion to other species and structures

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Thank you !

Jérôme Perin j.perin@ulg.ac.be