Models for mixed – species forests

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To cite this version:

Laurent Saint-André, Bruno Herault, Yann Nouvellon. Models for mixed – species forests: Review of some modelling concepts from pure to mixed-species stand. Summer School on Species Interactions in Mixed Forest Ecosystems (MIXFOR), nfz. Forestnet. INT., Aug 2014, Nancy, France. pp.37 slides. �hal-01269100�

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Saint-André L. - MixFor -

August 2014 1

forests

Review of some modelling concepts

from pure to mixed-species stands

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(adapted from Gordon B Bonan et al 2008, Science 320, 1444, Carbon and nutrient cycles Atmospheric deposits Fertilisation N fixation Soil solution Drainage Weathering Allocation and translocation Soil Organic matter Vegetation dynamics (D) and Forest managem ent (G)

Forest Ecosystems, owing to their nature, are

complex (temporally, spatially, …)

High expectation and pressure from the society (wood production, carbon sequestration, biodiversity, provision of drinkable water,..)

Impacted

by global changes but also

regulates biogeochemical cycles (climate change mitigation, interactions with the

atmosphere, species impact on the biological cycles)

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Modelling forest ecosystem structure and function

: 3 questions to be answered….

What is modelled ?

With which level of description?

And which modelling approach?

Time and spatial scales

3 Saint-André L. - MixFor -

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What is

modeled ?

Complexity

Number of models

Multi species, multi strata's Monospecific, evenaged stands

Mixed-species, even-aged stands

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Individual based models, distance independent Stand based models

?

Ingrowth

Moving up from one class to the next

Mortality

?

x y

Distribution based models

Individual based models, distance dependant

Which level of

description?

Multi species, multi strata's Monospecific, evenaged stands Mixed-species, even-aged stands 5 Saint-André L. - MixFor -

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And which modelling approach ?

Wood Production Water Quantity Infra-hour Hourly Daily Seasonal Several years Several decades C and nutrients Budgets/fluxes Phenomenological models Biogeochemical models Water Quality

Process-based models and Structural-functional models

Several centuries

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And which modelling approach ?

…. and different spatial scales

Global models

Tree and Stand Spatialized models

Tree and Stand models

PnET; Lignum, GreenLab, G’Day, ForSafe, Castanea, GO+ 3PG CO2Fix ForNBM Fagacée PP3, E-Dendro Empirical Process-based Tree Stand Forest Region Country Continent Comprehensive sites National networks of permanent plots National Forest Inventories (NFI) Remote sensing

Data for calibration, validation and forcing

NFI Matrix based models NFI grid models

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First set of take home messages,

after the introduction

Modelling forest ecosystem functioning is a long process….. Requiring permanent loops between concepts and field data

An unique “big” and “very powerful” model does not exist and is not desirable – a model is generally dedicated to one set of applications Models are scale dependent for calibration but can be applied to other scales if data are compatible (ex country by aggregation of NFI plots) The level of description does not determine the modeling approach

(Phenomenological, based, Biogeochemical, etc..) Ex – Process-based Big leaf models are stand Process-based models (as well a several growth and yield/phenomenological models)

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9

Rationale for wood production in pure

even-aged stands – and the related

Growth and Yield theories

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Tree and stand growth: case of even-aged and monospecific forests

-De Perthuis (1788)“Traité de l’aménagement et de la restauration des bois et des

forêts”

In Batho and Garcia, 2006

The concept of site index…. 1788

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Tree and stand growth: case of even-aged and monospecific forests

-Wood production

(volume) of a given tree species at a given stand mean (or top) height should be identical for all site classes.

- Soil fertility (site index) determines the time need to attain this height and volume. -A- Stand production

-Eichhorn’s rule

-Assmann’s yield

level theory

-There are some range of variations of

wood production at a given top height (variations related to the stockability issue)

From Maguire D, 2011

-Langsaeter

Hypothesis

-Losses in productivity

if the standing stock is too low

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Tree and stand growth: case of even-aged and monospecific forests

-B- Tree production

function of the overall stand production (see previously) which gives the potential moderated by two reducers

-an Index of Stand density (global pressure on the tree)

(stand density in itself (Sd), stand basal area (G), hart- becking

spacing factor based on tree growth without competition,

Reinecke density index (Rdi) and stand density Index (Sdi) based on the

self-thinning law, etc…)

- an Index of Social status of the tree (between tree competition)

(h/Ho, d/Do, the relationship between radial increment and tree diameter, etc…..)

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Tree and stand growth: case of even-aged and monospecific forests

-C- Biomass partitioning in the tree

-Ring area increases linearly from

the top of the tree to the crown basis and remains constant below the crown -Pressler’s law Ring area (cm2) D is ta nc e fr om t h e to p o f th e tr ee ( m ) Ring width(cm)

- From the pith to the bark and

along the tree bole. A three dimension map !

-Wood density variations

Trunk shape tends to become more cylindrical with time.

E.urophylla*pellita de 19 ans 0,30 0,40 0,50 0,60 0,70 0,80 0,90 -200 -100 0 100 200 distance à la moelle (mm) in fr a d e n si té ( g /c m 3) A B C

-Carbon allocation/partition to the organs

- function of age and available

resources 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 10 20 30 50 80 90 110 130 + Proportion de biomasse

Age du peuplement (ans)

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Tree and stand growth: case of even-aged and monospecific forests

y = 0.8957x + 1.2538 R2_{= 0.8874} 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140

Simulated AboveG Biomass (t/ha)

M e a s u re d A b o v e G B io m a s s ( t/ h a ) Biomass (t/ha) 0 50 100 150 200 250 300 350 400 450 N b d 'a rb re s Simulation Mesures 5 10 15 20 25 30 35 40 H a u te u r (m ) y = 0.9531x + 1.0724 R2_{= 0.9} 0 5 10 15 20 25 30 35 40 0 10 20 30 40

Simulated Dominant Height (m)

M ea su re d D o m in an t H ei g h t (m ) Dominant height(m)

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How valid could be these theories for

mixed-species stands?

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-Wood production (volume) of a

given tree species at a given stand mean (or top) height should be identical for all site classes.

- Soil fertility (site index) determines the time need to attain this height and volume.

-Eichhorn’s rule

SI Conversion equations (first published Doolittle 1958 !)

Or dominant height versus

Kahriman et al. 2013

Doolittle 1958

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Assmann’s yield level theory

Bouillet et al. 2013 Mixture is supposed to

change (increase) the

stockability and then increase the total standing biomass

Sometimes verified, sometimes not – See for example Bouillet et al. 2013 (acacia – eucalyptus mixtures)

+

-

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Assmann’s yield level theory

Mixture is supposed to change (increase) the

stockability and then increase the total standing biomass

Sometimes verified, sometimes

Mixture is increasing the occupation of the space (above or belowground)

Mixture is

increasing the resource

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Hypothesis

-Losses in productivity

if the standing stock is too low

but see also Zeide 2004, to get an X axis age-independant (not yet fitted on mixed-species experiments)

Torres-Joro, 2014

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process between dominant height and stand basal area growth)

Growth potential (function of ecological variables)

Reducer Stand density

Reducer Maturity

Vallet and Perot 2011

Species proportion

Mixture effect

Use of national forest inventory data (NFI) - large datasets

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21 Saint-André L. - MixFor - A generic approach for even-aged stands (Dhôte 1994, 1996, Saint-André et al. 2008)

Also working for mixed stands (Hein and Dhôte 2006 – Oak and Beech mixed-stands) Same mixture, impact of stand density, increase of between tree competition Impact of Site Index, relaxation of between tree competition

Impact of mixture (Beech pressure on Oak)

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Second set of take home messages, after the description

of the growth and yield approach (distance independent

models)

The concepts used for even-aged stands may also work for un even-aged and mixed-species stands (but few attempts have been done to verify this in a systematic way)

In all, this modelling approach is useful to detect, quantify, and hierarchize effects of site index, stand density and mixture effects, provided that height and diameter are measured (very few required datasets….)

BUT If it gives insight on overall stand production and between tree

competition, the interpretation of the processes behind requires different modeling and disciplinary approaches

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23

Lessons from other modelling

approaches?

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?

x y

Individual tree – Distance dependant - Growth and yield approach

Ex: Pretzsch et al. 2002, Mette et al.

2009 – temperate tree species

Crown shapes

Species height potential as function of environmental factors (climate, SWC, Soil nutrients)

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?

x y

Ex: Pretzsch et al. 2002, Mette et al.

2009 – temperate tree species

Simulation of mixed-species stands under current and future climate

Tests against known patterns (self-thinning equations)

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?

x y

Ex: Gourlet-Fleury and Houllier 2000; Gourlet-Fleury et al. 2005a,b; Degen et al. 2006 –

Diameter growth as a function of a

potential (site) x reducers (local density and its variation)

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?

x y

Ex: Gourlet-Fleury and Houllier 2000; Gourlet-Fleury et al. 2005a,b; Degen et al. 2006 – Tropical tree species

Grouping tree species according different traits

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?

x y

Ex: Gourlet-Fleury and Houllier 2000; Gourlet-Fleury et al. 2005a,b; Degen et al. 2006 –

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?

x y

Ex: Gourlet-Fleury and Houllier 2000; Gourlet-Fleury et al. 2005a,b; Degen et al. 2006 – Tropical tree species

impact of logging on genetic composition and demographic structure

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?

x y

Individual tree – Distance dependant – Process-Based approach

Ex: Duursma and Medlyn 2012, Medlyn 2004, Medlyn et al. 2007

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?

x y

Ex: Use of MAESTRA to explore species

interactions – Forrester and Albrecht 2014

http://maespa.github.io/

Light absorption and light use

efficiency in Mixed-Species stands (gradient of temperate sites)

Increased APAR and LUE in mixture, interaction with growing conditions

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?

x y

interactions – Le Maire et al. 2013

Light absorption and light use efficiency in Mixed-Species stands over a full rotation (Tropics)

Higher APAR in mixed

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?

x y

interactions –

Charbonnier et al. 2013

http://maespa.github.io/

Competition for light in agrosystems (Tropics – Erythina / Coffea)

Quantification of

photosynthetic photon flux density (Q) – even at low density, shade trees can reduce Q up to 14% annually

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Gap models – process-based

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Third set of take home messages, after the description of the

strength of individual based and distance dependent models

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Individual based distance dependent models, either G&Y or process-based, are useful tools to test hypothesis on the species interactions (light, water, nutrients) and give insights on community ecology and functional ecology

Rather than being in competition each other, the different modelling approaches are complementary

Saint-André L. - MixFor -

A promising research prospect is “the articulation of the concepts” between these approaches

But they require a huge amount of data, restricting then their use to very comprehensive sites

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0.020 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 5 10 15 20 25 30 35 T re e l e a f s u rf a c e , o r s te m p ro d u c ti o n , o r A P A R Tree Diameter (m)

Tree annual mean leaf surface (m-2) Tree stem production (kg yr-1)

APAR (GJ yr-1) (MAESTRA) Similarity of the

simulated pattern by MAESTRA

(segmented model) and the observed one (see slide 21 - relationship used in G&Y models) (Nouvellon and Dufrêne, unpublished data)

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Thanks for your attention !

This work was supported by a grant overseen by the French National Research Agency (ANR) as part of the "Investissements d'Avenir" program (ANR-11-LABX-0002-01, Lab of Excellence ARBRE). – Project QLSPIMS