scaling mediterranean biodiversity in space and...

Scaling Mediterranean biodiversity in space and time

Jacques Blondel

CNRS

Drivers of biodiversity: downscaling from global to local

Global, northern hemisphere: macrogeographical processes

Regional, Mediterranean: Plio-Pleistocene history

Local : environmental gradients

Landscape: local disturbance regime (moving mosaic)

Habitat: structure and dynamics



Regional (Mediterranean): Plio-Pleistocene history




Introduction

1.1*106 km² 1.2*106 km²

1.2*106 km²

The history of forest biotas in the Northern Hemisphere

Introduction

Trees: 253 Birds: 725



Geographical constraints: limits to dispersal

Introduction

Number of tree taxa in the three regions of the N.H. East. Nearctic West. Palearctic East. Palearctic

157 106 876 Genus East. Nearct. West. Pal. East. Pal.

Acer 10 9 66Alnus 5 4 14Betula 6 4 36Ulmus 4 3 30Magnolia 8 0 50Quercus 37 18 66Tilia 4 3 20

Latham & Ricklefs, 1993

Zonation of vegetation assemblages in the Mediterranean

Quézel & Médail, 2003

Climatic constraints : the Last Glacial Maximum (LGM)

Glace

Désert chaud

North–South migrations of European biotas (Huntley 1988) Inter-Glacial Full-Glacial

True migrations between ‘summer interglacials’ and ‘winter glacials’

PHYLOGEOGRAPH AND SUTURE ZONES

R R R

Genetic diversity is particularly high in the Mediterranean region

R R R R

G

I G

Taberlet et al., 1998

Distribution of richness (up) and rarity (below) of plants, birds and amphibians/reptiles in Europe (Araujo et al., 2005)

Plants Birds Herptiles

ENDEMISM RATES

Groups N Species % Endemism

Vascular plants 25 000 50.0 Freshwater fish 450 44.0 Reptiles 165 68.5 Amphibians 63 58.7 Mammals 197 25.5 Birds 343 17.0 Insects 150 000 + ? Very high

Oro-mediterranean

Supra-mediterranean

Meso-mediterranean

Montane-mediterranean




Local: environmental gradients



Primeval forest in ex-Yougoslavia (Mueller-Dombois, 1987)

metaclimax

Primeval forests are moving mosaics driven by disturbance events that initiate

successions

Succession of communities

Seral stages (succession = forest domain)

α α α α

γ β β β

Spatial scaling

The extent of ecosystem structural change is reflected by the horizontal distance from the original stable state. The effort required to return the degraded state to a trajectory of recovery towards the original stable state is reflected by the depth of the attraction basin

The forest domain: attraction basins

Extent of structural change from the stable steady state

Res

ista

nce

to sh

ift to

an

alte

rnat

ive

stab

le st

ate

High matorral Middle matorral

Low matorral

Dynamic mosaic of forest states

No fire

Fire

The extent of ecosystem structural change is reflected by the horizontal distance from the original stable state. The effort required to return the degraded state to a trajectory of recovery towards the original stable state is reflected by the depth of the attraction basin

Res

ista

nce

to sh

ift to

an

alnt

erna

tive

stab

le st

ate

Extent of structural change from the stable steady state After Ghazoul et al. 2015

Dynamic mosaic of forest states

Fire

Low fire return

The forest domain: attraction basins

High fire return No fire

‘Metasystem’ =

moving mosaïcs

Quercus Pistacia palaestina

Calicotome Pistacia lentiscus

Cistus Sarcopoterium

Paeonia mascula

The size and

connectivity of habitat

patches depend on the

dispersal range and the

speed of dispersal of

organisms

27 Jedrzejewski et al.

1988

Dead wood habitats

By their massive production of lignous tissues that are difficult to recycle, forest ecosystems evolved the most complex set of communities of nutrient regenerating

organisms to be found in terrestrial ecosystems (succession of communities, diversity of adaptive types,

symbioses, competition, parasitism etc.)

Dead trees are spots of very high biodiversity







Humans as ‘neo-drivers’ of

biodiversity

1987 2001

The lost Eden paradigm

The paradigm of the human-designed garden

1ère

Produits forestiers

Fabrication du verre

Bois de feuCharbon de boisTanninBois de BuisHuile de cadeBois d’outillageFourragePharmacopée

Glands et fruitsChampignons

Pâturage

Viticulture

Pl. aromatiques

Révolution Guerres mondiales2nde

1750 1850 195019001800 2000

1ère

Produits forestiers




Pâturage

Viticulture

Pl. aromatiques


1750 1850 195019001800 2000

Produits forestiers




Pâturage

Viticulture

Pl. aromatiques

Produits forestiers




Pâturage

ViticultureViticulture

Pl. aromatiques


1750 1850 195019001800 2000


Révolution Guerres mondialesRévolution Guerres mondiales2nde

1750 1850 195019001800 200017501750 18501850 19501950190019001800 20002000

Ecosystem services from forests

The millenial transformations of Mediterranean forests

Selon l’usage que les humains en font, Les surfaces boisées peuvent être:

– Forêts de subsistance, – Forêt à usage industriel, – Forêts de production de bois, – Forêts sanctuaires – Forêts de pâturage – Forêts de récolte des fruits et

de produits divers (châtaignes, liège)

« Le forêt est un miroir de la

société » (A. Corvol 1987)

Début de la déforestation massive

9000 BP

5000 BP

Fairly high

low

moderate

moderate

high

high

high

low

high

Dehesa-montado

Silva-saltus-ager

Primitive oak forest

Effects of traditional land use practices on biodiversity

F. Bousquet & D. Gautier, 1999

Diversity

Take home messages • Biodiversity is a legacy of long-term processes that are rooted in a deep past operating from

local to global

• Forests functions and services depend on many habitat types which contribute to the dynamics of the system (old stands are not « better » than young ones)

• Local regimes of natural disturbance are a prerequisite for forest dynamics and for the survival of the historical legacy of biodiversity

• Connectivity among habitat patches of similar structure is necessary for long term survival of (meta)populations and (meta)communities

• Address key challenges of mitigation and adaptation to global change

• A golden rule, the ‘5 M’: « Making Mimics Means Managing Mixtures » (Dawson & Fry, 1998) (i.e. the sustainability of mimic systems depend on how well we work within the natural ecological forest dynamics)

scaling mediterranean biodiversity in space and...

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