Adaptation of mountain regions to drought recurrence in a context of global change

Baptiste NETTIER, Irstea

Sandra Lavorel, Pénélope Lamarque, CNRS - LECA Benoît Courbaud, Laurent Dobremez, François Véron, Irstea

Richard Bonet, Ecrins National Park

Recent climatic trends in the French Alps

Precipitation T min T max

A context of great uncertainty

SECALP project

Objective: To analyse adaptation mechanisms for mountain regions in the face of climate change, especially recurring droughts

– Mechanisms of ecosystem resilience and transformation

– Processes of adaptation for livestock farming and forestry

– Expected effects of climate change scenarios, in the context of social transformations

Guidelines for supporting managers through policy and infrastructure

Strategies for long term observation

Ecosystem adaptation

Land use adaptation

Scenarios and pathways to sustainable

management

Long-term observation system

SECALP: An integrated conceptual framework

2 territories of the French Alps LTSER

Villar d’Arène, Oisans Vercors

• Vercors: • Subalpine Extern Alps • Dairy farming systems, suckler cattle and

sheep farming systems, transhumants

• Oisans: • High mountain Intern Alps • Suckler cattle and sheep farming systems

21 sites sampled in 1988, 2001 and 2011 Grande Cabane grassland (Vercors)

Grazed / ungrazed plots since 1988

• Small changes and stability in grazing value • Grazing stabilises composition and increases diversity even under drought

-0.5 3.0

-0.5

2

.0

AP11

AD11 BP11

BD11

DP11

DD11

EP11

ED11 FP11

FD11

HP11 HD11

IP11

JP11

KP11 KD11

AP88

AD88

BP88

BD88

DD88

DP88 ED88

EP88

FD88

FP88

HP88

HD88

IP88

JP88

KD88

KP88

AP01

AD01

BP01

BD01 DP01 DD01

EP01

ED01

FP01 FD01

HP01

HD01

IP01

JP01

KP01

Dry grasslands Mesic grasslands

Forest clearings

Expected trend from 1988 to 2011 under strong drought response

No shift towards drought tolerant species = stability

A detectable effect of climate change on summer pastures?

© G. Loucougaray

Experimental drought and heat wave simulation on Lautaret and Vercors grasslands

- ↘80% summer precipitations + 1°C night warming

- Extreme event (~2003): one month without precipitation (Lautaret & Vercors) + heat wave +6°C (Lautaret)

- Mowing (0/1) – combined with the climate treatment

Lautaret

Vercors

Limited sensitivity to drought: transient response (Vercors) or resistance (Lautaret) Short term: prevailing effects of management Long term: feedbacks via nutrient cycling

© S. Aubert © S. Lavorel © G. Loucougaray

1900 1920 1940 1960 1980 2000

05

15

25

35

Mort

alit

y r

ate

Lanslebourg

1900 1920 1940 1960 1980 2000

05

10

15 Queige

1900 1920 1940 1960 1980 2000

01

23

4

Mort

alit

y r

ate

Engins mortality rate

CI

1900 1920 1940 1960 1980 2000

0.0

0.5

1.0

1.5

Méaudre

Are there discernable effects of drought years on tree mortality?

• Overall low mortality rates and no long term trend

• Links to climate variables: – Strongly predominant effects of storms (yr n or n-1)

– No effect of the Palmer Drought Severity Index (Climatic Research Unit, Norwich)

– 2nd order effect of increased precipitation

Perception by farmers and shepherds of consequences of droughts since 2003, and reactions

• Decrease in forage resources • Decrease in water availability for summering herds • Few vegetation dynamics – “Invasions” by undesirable

species, superficial soil degradation

• Signs of climate change - “Fewer storms in summer"

Adaptations at farm scale

– Impacts and adaptation options differ widely across farming systems (level of reliance on winter fodder)

– Mainly tactic responses without long-term adaptation : decrease of grazing pressure, fodder purchase

– Pastoral systems have integrated the hypothesis of increasingly frequent droughts into their functioning and made structural adaptations

– Drought is only one risk among others for livestock systems: socio-economic context, structural constraints

What adaptations in case of harder droughts ? What consequences for ecosystems

Nettier et al., 2010

Perception by foresters of consequences of droughts since 2003, and reactions

• 2003: strong defoliation on drier / thinner soils, but not in productive stands; good recovery with only limited mortality

• Beetle damage on spruce in 2004-5

• Foresters are aware of climate change and the risk of recurring droughts, but are yet to see climate change effects

• Adaptation responses are limited:

– Manage stands towards species and structural diversity

– Reduce the share of spruce in regional plans

– Infrastructure for increased fire risk

– Inconclusive attemps to plant more southern species (frost)

2003

2004-5

Building of prospective scenarios

• Co-construction with a group of local experts

• 4 contrasted scenarios, combining:

– 2 climatic contexts

– 2 socio-economic contexts

• Time path: 30 years trends + precisions for the next 4 years (CAP reform)

• Return to the farmers and foresters : strategic adaptations

– Storylines

– Drawings (landscape changes)

– Graphs (forage productivity, CAP subsidies, product prices)

• With local experts : consequences at territorial level

“Intermittent” climate

“Territorial” context

Scen.3

Scen.4

Scen.1

Scen.2

“Shock” climate

“Global” context

Reactions to scenarios: main trends

Intermittent + Global Leverage system flexibility, increase surfaces, decrease

livestock as a last resort

Intermittent +

Territorial Leverage system flexibility

and increase surfaces + develop direct sales

Shock + Global Decrease livestock and take on off-farm; put a stop to

the farm in some cases

Shock + Territorial Decrease livestock,

develop direct sales + agri-tourism

Territorial On-farm

diversification

Shock Decrease livestock

Intermittent Adapt to the situation as in the past + increasing

system flexibility to limit fodder purchases

Global Offset loss of

income through an

activity outside the

farm / stop the farm

A role playing game to simulate grassland management according to the different scenarios

Results

Local International

a) Current context

Game board (Round 4)

Decisions-basedrules

b) Scenarios

7%12%

11%

7%22%

42%

Actuel

1 2 3 4 5 7

14%

14%

6%2%

22%

42%

Choc territorial

3 3f 4 4f 5 7

9%1%

15%2%

3%25%

2%

42%

Choc global

1 2 3 3f 4 5 5f 7

13% 6%

8%1%

6%2%22%

0%

42%

graduel territorial

1 2 3 3f 4 4f 5 5f 7

11%2%

13%2%

4%1%24%

1%

42%

graduel global

1 2 3 3f 4 4f 5 5f 7

Game board (Initial state)

Inte

rmit

ten

tD

rast

ic

Lamarque et al., 2013

Dro

ugh

t

Socio-political context

Projection of the game on the territory

Ecosystem services modelling at the landscape scale

Agronomic value Cultural value

Pollination value Soil C stocks

Regulation value Total ES value

Lavorel et al. J. Ecol. 2011

Lessons from the scenarios

Effects of the climatic hypothesis • Intermittent drought context already integrated by farmers, even if the forage

systems are not always adapted and many still have to buy fodder.

• Shock climate context difficult for farming systems degradation of economic and work conditions + important farming system and land use tranformations

Effects of the socioeconomic hypothesis • Farmers’ preference for the territorial context: more adapted to mountain farming;

many farmers had already diversification projects

• Global context: interesting subsidies easy to get, but discordant with conception of job (AEM for wild nature or carbon storage with planting trees…)

• Most of the farmers ready to take out further commitment (diversification)

• Local experts were surprised, even if such changes are already

emerging

• They underlined a need of collective facilities in order to support

diversification (local abattoirs, sales outlets, formation, structuration of

short distribution channels…)

A need of territorial action to accompany adaptation

Conclusion: resilience or fragility of mountain territories?

• Ecosystem adaptation to environmental variability – Buffer mechanisms: e.g. plant belowground reserves, rapid soil microbial

responses

– BUT:

• thresholds?

• Sensitivity to practices evolutions : fragile equilibrium

• Adaptation of actors to environmental variability – Mainly tactic short term responses

– Resistant systems but limited resilience ?

• Systems under strong constraints – Biophysical limits to production (short growth period, slope…)

– Rigid rules (CAP, land access regulations …)

• A need of local knowledge on ecosystems functioning in this changing context – How climate, practices, and vegetation co-evolve ? How to manage it ?

– Need of dialogue and cooperation at a territorial level

An interdisciplinary and participative long term monitoring system

Different protocols to survey vegetation, climate, management

A sample of diversified alpine pastures and farms

Co-construction of knowledge

A conceptual model for data analyzing

An interdisciplinary and participative long term monitoring system

Thank you for your attention !

Three different reasoning and choices

“I would reduce the economic impact of droughts by diversifying my productions and my activities” Cereal, poultry workshop, agri-tourism or city work, according to the context

“I would adapt but without diversifying my productions because I want to keep my livestock farmer identity” Possible direct sales of meat, salaried work, but in connection with livestock

“I wouldn’t change my system because it is already robust enough” Oversized haymaking surfaces or source of income from another activity

• differences in livestock farmers “identity” according to the types of farming systems:

• Oisans “High mountain” systems : produce hay vs. buy hay

• Vercors “Fodder” systems: type of production

• Vercors “Pastoral” systems: “pastoralist” vs. “grass farmer”

Uncertainties on expected climate trends… Number of days of heat wave

Length of drought

Mean max summer T

Mean annual precipitation

Intermittent

Regional

Global

Shock

Four scenarios, combining climatic and socio-economic contexts

2. BUILDING OF PROSPECTIVE SCENARIOS

2 climatic contexts

Intermittent • Spring or summer droughts alternating with wetter years • Species resilience • In a drought year : 1st cut yield = 60% of a wet year

Shock • 4 consecutive spring drought years • Rangeland: deterioration of herbaceous plants • 40% loss in fodder resource for long term

2 socio-economic contexts

Global • Roles of agriculture: attractive landscape for city dwellers; carbon storage

• Product prices : ≈ -20% (Organic:-10%) • CAP pillar 1: -20%, decoupled, minimum guaranteed • AEM: bonus for grassland, planting trees

Territorial • Roles of agriculture: local quality products • Product prices:≈ -20%,except organic & PDO label: maintained • CAP Pillar 1: -20% • AEM: Bonus for biodiversity, commitment to results

Effets des scénarios sur les services écosystémiques

0

20

40

60

80

100SOM

RetentNO3

Gbio

LitterMass

CPC

FloweringOnset

PlantDiv

NMP

0

20

40

60

80

100SOM

RetentNO3

Gbio

LitterMass

CPC

FloweringOnset

PlantDiv

NMP

Lamarque et al., in prep.

Land management types

Soil organic matter

Nitrate retention

Fodder production

Standing litter

Fodder quality

Flowering onset

Plant diversity

N mineralization

Current

Scenarios

Drastic drought induces a shift from production and cultural services of interest to local stakeholders to higher levels of regulation services of interest to stakeholders outside the study site

Management change scenarios in response to combined climate and social chanee

Local International Future scenarios

7%12%

11%

7%22%

42%

Actuel

1 2 3 4 5 7

14%

14%

6%2%

22%

42%

Choc territorial

3 3f 4 4f 5 7

9%1%

15%2%

3%25%

2%

42%

Choc global

1 2 3 3f 4 5 5f 7

13% 6%

8%1%

6%2%22%

0%

42%

graduel territorial

1 2 3 3f 4 4f 5 5f 7

11%2%

13%2%

4%1%24%

1%

42%

graduel global

1 2 3 3f 4 4f 5 5f 7

Inte

rmit

ten

t D

rast

ic

Current situation