Desurvey: W.P.1.3.3

John B. Thornes (K.c.l)• W.P.Specific Objective• …to provide a generic

desertification model that can be readily applied to desertification scenarios (identified from the PIK syndrome approach) as applied to the European bio-physical and socio-economic environments

• Stressing:• ……. The interaction between the

socio-economic and bio-physical drivers and….

• ……….Sustainable renewable resources model of Gutierrez and adapted for desertification by Puigdefabrigas for desertification.

Develop a surveillance system that to assess and diagnose desertification. Contribute to strengthen the necessary scientific knowledge for the future orientation of the sustainable Development Strategy and the 6th Environment Action Programme

Lagadas County Pilot Site, Greece bypermission of V. Papanastasis

Desurvey Mission

• Requirements

• Interface

• Machine

• Requirements• Multiscaling• Ease of parameterisation• Readily available data sources• Policy-implementation

• Interface• Computer-based• different scales• different land-uses

• Machine• PC platform• Object –oriented implementation• Graphic output

Syndromes for AlentejoTable 1.3.3.(2)

syndrome Symptoms Interacting variables

SAHELPre-1890 Rural poverty and population pressure drives farmers to overuse marginal land

Climate, productivity and population

ARAL SEA(1940-1960) Bad management or failure of centrally planned,large scale projects involving deliberate reshaping of the natural environment

Govt. policy on wheat.Wheat productionLand degradation

DUST BOWL1960-1990 Industrialised farming inWheat campaign

Vegetation cover, soil erosion, population densities

SAHEL(AGAIN)(1980-2000)

Overuse of marginal land E.U. subsidies, extensification of agriculture, new farming ‘intakes’ from commons.

RURAL EXODUS(200-) Abandonment of traditional agricultural practices

Abandonment of land, population changes,

A group of signs and symptoms which, when present together allow the description and naming of a particular disease

Regev-Gutierrez

• U. Regev and A. Gutierrez have developed a new economic-ecology paradigm

• Based on the multi-level food chain, with resources at bottom, and human harvesting at top.

• It is constrained by objective functions(such as private maximization of gain, or community sustainability.

• The result is contained in a stability analysis

Resources-Rain/sunshin-nutrients

VegetationVegetation

GrazersGrazers

Harvesters

Source

Production

Consumption

alpha coefficient according to alpha= 1-exp(-b*m), with b=0.023

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800

Series1

Logistic growth for level i minus respiration

Take-off by predator at level i+1

α coefficient (y) against biomass

Baumgartner-Gutierrez equation for mass change at level i

Xi is mass at i th level exponent is ratio of supply at next lower level (i-1) to demand at this level

Ci is conversion of demand (di) at ith level u i is respiration demand at level i

Respiration term

Gutierrez-Baumgartner fnct of growth relative to different supply/demand ratios

0

0.2

0.4

0.6

0.8

1

1.2

0 100 200 300 400 500

supply for constant demand

(1-e

xp(s

uppl

y/de

man

d)

D=40 D=50 D=80 D=90

Herbivore isocline vs M1,M2,M3From Gutierrez(1996) Fig. 8.1

Gutierrez, A.P.(1996) Applied Population Ecology, A Supply-Demand Approach. Wiley

Herbivore isocline (M2)vs M1

From Gutierrez(1996)Fig8.1)

α is apparency of trophic level to its consumer (how easy it is to get food)

θ2D2 is converted demand from this level

M1 is plant (resource in this case)

M2 a herbivore

M3 a predator

Resource-soil

Producer

Consumer

Soil erosion model

Landdegradation

climateclimate

Modified erosion

topography

Plant growth model

Economic ecology model

Baumgartner-Gutierrez equation for mass change of vegetation

dM1/dt={θ1(1-e-λ1)D1 -r1M1b1}M1 Metabolic pool equation plants -(1-e-λ2)D2M2 Loss to herbivores in level above

λ1=α1M0/D1M1 ratio of supply of resource to Demand from plants

λ2 = α2M2D3/D3M3 ratio of supply of herbivores to Demand from predators

M1=vegetation M2=herbivores M3=carnivoresM0=rain

α=accessibility

Θ=conversion factor

Appendix I