MycorrhizasMycorrhizas: evidence for their : evidence for their key role in sustainable forest key role in sustainable forest

managementmanagement

Dr. Suzanne Dr. Suzanne SimardSimard

Resources Resources naturellesnaturelles Canada/Natural Resources Canada/Natural Resources

Canada, Oct. 2010Canada, Oct. 2010

To discuss the role of complexity science and mycorrhizal fungi in managing forests sustainably in

our changing climate.

•

Sustainable forest management, climate change and disturbance

•

Complex systems•

Mycorrhizas

and mycorrhizal

networks

•

Network structure in Douglas-fir forests•

Network facilitation of Douglas-fir regeneration

•

Conserving of networks and complexity for sustainable forest management

Contents

Sustainable Forest Management

“A thing is right when it tends to preserve the integrity, stability and beauty of the biotic community. It is wrong when it tends otherwise.” Aldo Leopold

Complex System•

A system with many parts

•

The parts interact (inter- dependent, feedbacks)

•

The whole is greater than the sum of the parts (interactions give rise to emergent properties).

•

Bottom-up self-organization•

Non-linear

•

Resilient system

Environmental Change and Loss of Complexity

Population Growth and Consumption

Agriculture ForestryIndustry

Land Use ChangeGHG Increases Nitrogen Increases Exotic Invasion

Climate Change

Losses in Ecosystem Complexity

Loss of Biodiversity

Modified from Vitousek

1994, Diamond 2007

Social demandsPolitics

EconomicsPolicy

Unexpectedconsequences

With 2XCO2 climate forcing

Current biome distribution

IPCC 2007

2025

Predicted climatic envelopes (1975-2085) of biogeoclimatic zones in British Columbia

20552085

Hamann

and Wang (2007) Ecology

Mountain pine beetle in British Columbia

History of harvesting levels in British Columbia

Hagerman et al. 2010

Silviculture

Systems in BC: 2009 95% clearcut

or clearcut-with-reserves

010,00020,00030,00040,00050,00060,00070,000

Coast Southern Interior Northern Interior

Area (hectares)

British Columbia Ministry of Forests (2009)

Complex System•

A system with many parts

•

The parts interact (inter- dependent, feedbacks)

•

The whole is greater than the sum of the parts (interactions give rise to emergent properties).

•

Bottom-up self-organization•

Non-linear

•

Resilient system

myco

(fungus)

rhiza

(root)

Mycorrhizal

network:

mycelia that connects plants

Universal Nature of Mycorrhizal Symbioses

• Ca. 80% of land plants form mycorrhiza• All terrestrial ecosystems prominently

feature mycorrhizal functioning

•• Hypothesized that theHypothesized that theearliest land plants adaptedearliest land plants adaptedto terrestrial habit via to terrestrial habit via mycorrhizalmycorrhizal

functioningfunctioning

Fossil VA Fossil VA mycorrhizaemycorrhizae

from Devonianfrom Devonian(Taylor et al. 1995)(Taylor et al. 1995)

Randy Molina

Classes of MycorrhizaeArbuscularArbuscular

mycorrhizaemycorrhizae

EctomycorrhizaeEctomycorrhizae

Ericoid Ericoid mycorrihzaemycorrihzae

OrchidoidOrchidoid

mycorrhizaemycorrhizae

Randy Molina

Ectomycorrhizae

Randy Molina

Randy Molina

Over 1.5 million estimated species, most undescribed, many rare or little-known

PilodermaPiloderma croceumcroceum + hemlock+ hemlock RhizopogonRhizopogon occidentalisoccidentalis + + Ponderosa pinePonderosa pine

Extending the Root ZoneExtending the Root Zone

Randy Molina

The trees of Canada are obligate mutualists

with mycorrhizal

fungi

• Fungi are essential for tree survival• Trees are essential for fungal survival• Explore soil volume 100X greater• Increase nutrient uptake (N, P)• Increase water uptake, drought tolerance• Enzymatic capabilities• Prevent plant pathogenic infection• Prevent heavy metal toxicity • Provide food for other organisms• Increase the life-span of roots• Improve soil structure• Soil weathering and nutrient mobilization• Connect plants together and affect plant

community dynamics

Most ectomycorrhizas

of trees have broad host ranges

Amanita Amanita muscariamuscariaLaccariaLaccaria laccatalaccata

PisolithusPisolithus tinctoriustinctorius

Mycorrhizal

networks underpin soils as complex adaptive systems

Lian

et al. 2006Pinus densiflora, Tricholoma matsutaki

Read et al. 1985Pinus sylvestris, Suillus bovinus

Mycorrhizal

networks: cross-scale interactions and emergence of self-

organizationStand structure is

emergent property

Regular RandomRandom ScaleScale--freefree

Network structure controls system behavior

30x30mMulti-cohort stand, 15-94 years old

DNA sequencing of ITS region to determine taxaMicrosatellite markers of fungal and tree DNA to distinguish individuals

Trees, sampling locations, root lengths

R. vesiculosus genets (blue)R. vinicolor genets (pink)Up to 19 trees per genetAll trees interconnected by <

3 degrees of separation

Largest hub tree connected to 47 other trees (65 total)

Heterogenous

(scale-free) network:Highly interconnected, easily traversed, living and growing

Resilient to random removal of links but vulnerable to targeted removal of key node

Size of nodes ∞

tree diameter; Color shade ∞

tree cohort

(c)

(b)

(d)

(a)

Most highly linked hub removed Most linking fungal genet removed

20% of trees removed at randomAll oldest trees removed

0.5μm=soil transfer only35μm=soil + hyphae250μm=soil + hyphae

+ rhizomorphsNo=soil + hypahe

+ rhizomorphs

+ short distance explorers

Survival of 2-yr-old germinants

(%)

Car

bon

trans

ferr

ed to

–yr

ger

min

ants

(exc

ess 13

C (m

g))

0.5μm=soil transfer only35μm=soil + hyphae250μm=soil + hyphae

+ rhizomorphsNo=soil + hypahe

+ rhizomorphs

+ short distance explorers

Removal of hub trees causes networks to simplify, compromising natural

regeneration potential and opening space for exotic invasions

Ignoring complexity and mismanaging mycorrhizas

Summary•Forests threatened by climate change & disturbance •Sustaining forest requires complex systems approach •Mycorrhizal

networks are fundamental to self-

organization of complex forest ecosystems •All Douglas-fir trees are joined in a network•Old trees nurse new regeneration via networks•When key hub-trees are removed, the networks may collapse, contributing to regeneration failure

•Complex systems normally resilient to disturbance may shift to new domain with climate change

•Conservation of forests and their components as complex systems critical for sustainability

Conservation Principles

•

Protect fungi, including rare species, and fungal hotspots

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Limit extent of harvesting, set aside reserves•

Maintain legacy trees and limit size of clearcuts

•

Maintain or restore tree diversity•

Maintain or restore coarse wood on the forest floor and in the soil

•

Maintain habitat diversity & connectivity across scales

•

Maintain networks of communication