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Raffaele Pelorosso, Federica Gobattoni, Roberto Monaco and Antonio Leone on "A new approach for the assessment of landscape evolution scenarios: from whole to local scale"
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Seventh International Conference on Informatics and Urban and Regional Planning
10‐12 May 2012, University of Cagliari
A new approach for the assessment of landscape evolution scenarios: from whole to
local scale. by Raffaele Pelorosso1, Federica Gobattoni1, Roberto Monaco2 and Antonio Leone1 .
1 DAFNE Department, University of Tuscia, Viterbo, Italy.2 Dipartimento Interateneo di Scienze, Progetto e Politiche del Territorio, Politecnico di Torino, Torino, Italy
Landscape EquilibriumLandscape continuously evolves. The interactions between human actions and natural
processes are evolved together researching an equilibrium, usually precarious or metastable, based on fundamental physics laws as the energy conservation and entropy
growing principles (Kleidon, 2010; Naveh, 1987; Pelorosso et al., 2011).
All ecosystems, as open systems, continuously exchange energy, nutrients and biomass with the environment through irreversible processes.
Ecosystems evolve developing highly ordered, lower entropy structures to increase the total dissipation of energy and maximize the “global”production of entropy(Gobattoni et al., 2011).
Ecosystems strive to increase their ability to degrade incoming solar energy, and much of this dissipation occurs through vegetation (Brunsel at al., 2011).
Landscape is a complex system
flux
flux
flux
More energy exchange more landscape resilience and biodiversity are ensured
Human actions (infrastructures, urban development, natural resources exploitation etc) behave as external constraints imposed on the eco‐system, reducing flows of energy and matter; they alter the dynamic equilibrium affecting landscape evolution in terms of functionality, biodiversity reduction, as well as accelerated erosion phenomena and hydrological instability.These external constraints represent obstacles to the connected fluxes of energy and matter (barriers), leading to local reduction of entropy and to the creation of organized systems (Chakrabartiand Ghosh, 2010).
Modelling the energy fluxes and variation of landscape energetic equilibrium state, is therefore interesting because it could allow to assess the most suitable plan strategies for natural resources conservation management and landscape functionality preservation.
Numerous physical and empirical models have been developed to simulate landscape and vegetation dynamics in time in order to explain environmental evolution and equilibrium conditions.
Although these efforts, a macroscopic theory about landscape rules and its variables still lacks (Chakrabarti and Ghosh, 2010; Coulthard, 2001; Jorgensen, 2004) and if some equilibrium is observed it may only be seen at certain spatio‐temporal scales (Pickett at al., 1994).
Introduction
2000
2005
Urban sprawl
An innovative procedure, called PANDORA, Procedure for mAthematical aNalysis of lanDscape evOlution and equilibRium scenarios Assessment, was proposed to assess the effects of different planning strategies on final possible equilibrium states that are energetically stable. It provides a tool for the evaluation of landscape functionality and its resilience. PANDORA, linking together thermodynamic concepts, mathematical equilibrium, metabolic theory and landscape metrics, allows to model landscape evolution in time under the impact of external constraints and giving a unique response from it in terms of energy. All the parameters required by the mathematical model can be obtained from GIS data, which are usually available to land managers.The model is proposed as a Decision Support System for choosing among possible planning strategies following a holistic approach.
GOBATTONI F., LAURO G., LEONE A., MONACO R., PELOROSSO R. (2010). “A mathematical procedure for the evolution of future landscapes scenarios”. LIVING LANDSCAPE The European Landscape Convention in research perspective.” Firenze, 18‐19 Ottobre 2010. Vol II. ISBN 978‐88‐8341‐459‐6.
GOBATTONI F., LAURO G., LEONE A., MONACO R., PELOROSSO R. (2010). “A mathematical procedure for the evolution of future landscapes scenarios”. La Matematica e le Sue Applicazioni n°11. Hard copy ISSN 1974‐3041. Online ISSN 1974‐305X.
GOBATTONI F., PELOROSSO R., LAURO G., LEONE A., MONACO R. (2011). PANDORA: Procedure for mAthematical aNalysis of lanDscape evOlution and equilibRium scenarios Assessment. EGU General Assembly, Session ERE 5.1 Landscape functionality and conservation management, 3 ‐ 8 April 2011, Vienna, Austria. Vol. 13, EGU2011‐4023‐1, 2011.
GOBATTONI F., PELOROSSO R., LAURO G., LEONE A., MONACO R. (2011). A procedure for mathematical analysis of landscape evolution and equilibrium scenarios assessment. Landscape and Urban Planning, 103:289‐302.
GOBATTONI F., LAURO G., MONACO R. PELOROSSO R. (2012). Mathematical models in landscape ecology: Stability analysis and numerical tests. SUBMITTED.
For more details:
PANDORA: Procedure for mAthematical aNalysis of lanDscape
evOlution and equilibRium scenarios Assessment.
PANDORAmodel was proposed to assess the effects of different planning strategies on final possible equilibrium states that are energetically stable. It is able to describe and assess the environmental fragmentation due to external constrictions .The whole model implementation procedure is constituted by 3 sequential steps :
1) Landscape Units definition
2) Calculation of GeneralizedBiological Energy and Landscape graph building
3) Resolution of differentialequations
[ ] ),()(1)(1)()(
max
' tMtVkM
tMtcMtM −−⎥⎦
⎤⎢⎣
⎡−=
[ ] ),()(1)()(' 0 tVUhtVtVbtV T −−=
46 Landscape UnitsMinumun LU 0.36 Km2
Maximun LU 29.26 Km2
In this case, a Landscape Unit (LU) is considered as an area delimited by significant barriers to energy fluxes. LUswere pointed out by means of holistic classification method (Van Eetvelde and Antrop, 2009).
Most important factors that represent the barriers to energy fluxes were weighted (Saaty matrix) and used to individuate LUs.
In order of importance used barriers can be identified as follows:
1) Main roads and railways
2) Lines of change between very different soil types
3) Limits between hill and mountain areas
1. Landscape UnitsIdentification
The energy flow between LUs can be derived from Biological Territorial Capacity, BTC, (Ingegnoli, 2002) through the definition of a Generalized Biological Energy as the available energy for each LU. M is the energy available for exchange between LUs and it depends on several intrinsic characteristics of each LU such as energetic diversity inside it, barriers in it, shape, climatic conditions, permeabilities of the boundaries and so on.
Land cover
BTC, Biological Territorial CapacityIngegnoli (2002)
Generalized BiologicalEnergy (GBE) or bio‐energyof LUj
LU characteristics(energy diversity, shape, climatic conditions,……)
( ) Jjj BKM ⋅+= 1
5/)( Ej
Cj
Dj
Pj
Sjj KKKKKK ++++=
2. Calculation of GeneralizedBiological Energy and
Landscape graph building
BTC, Biological Territorial Capacity, is a physical quantity measured in Mcal/m2/year, linked with the capacity of vegetation to transform solarenergy. By considering the concepts of biodiversity (i.e., landscape diversity), resistance stability and the principal ecosystem types and their metabolic data (biomass, gross primary production, respiration), the BTC index seems to sum up the available energy in an ecosystem.The BTC index can assess the flux of energy that an ecological system needs to dissipate to maintain its level of metastability, i.e., its temporaneousstability condition
Calcolation of GeneralizedBiological Energy
‐Barriers with different degrees of permeability to the flow of bio‐energy.
‐Bio‐energy (M) of each LU represented by proportional nodes.
‐Energy exchange flux, (F), between LUsdepends on the degree of permeability of the barriers.
‐Connections between LUs are represented by arcs, whose thickness is proportional to the magnitude of the energy flux between LUs
Landscape Graph building
2. Calculation of GeneralizedBiological Energy and
Landscape graph building
ji
ijijji
i j PP
pLMMF
+⋅
+=
2
Mi and Mj are the Generalized Biological Energies correspondent to LU‐i and LU‐j, respectively, Lij is the length of the boundary between LU‐i and LU‐j and Pi and Pj are the perimeters of LUi and LUj, respectively. pij ∈ [0;1] is the mean permeability index of such a boundary.
Analysis of M and V variation in time t until the reaching of mathematical equilibrium (asymptotic)
V(t)= fraction of the total territory occupied by areas with high values of BTC (e.g forests)
M(t)= Generalized Biological Energy of the whole system. It is derived from BTC values and intrinsic characteristics of each LU
[ ] ),()(1)(1)()(
max
' tMtVkM
tMtcMtM −−⎥⎦
⎤⎢⎣
⎡−= [ ] ),()(1)()(' 0 tVUhtVtVbtV T −−=
3. Resolution of differentialequations
•U0 depends on urban areas (compact and sprawl)•h depends on urban perimeters (compact and sprawl)•k depends on global impermeability of barriers•bt is related to mean BTC value of the system•c is the connectivity index and depends on number and amount of fluxes
The PANDORA evolution model uses a system of two nonlinear differential equations (a kind of Lotka‐Volterra model) and is based on a balance law between a logistic growth of energy and its reduction due to limiting factors coming from environmental constraints
Beside the interesting results, the model presents some drawbacks:1‐ parameters bT and c are time‐independent (this assumption is not realistic since bio‐energy production and connectivity must change during environment evolution). 2‐ relative small and/or localized modifications of landscape connectivity and GBE could be not well assessed by the model. Indeed, the model works with global variables for all the system and local environmental quality variations could be balanced by the response of another portion of the studied territory.
For these reasons a new model, overcoming these simplifications, is proposed (PANDORA2?) on the basis of the following aims:
1) To investigate the landscape evolution at the level of each LU and not only at that of the whole environment under investigation;
2) To re‐define the connectivity index making it time‐dependent so that the links between the LUs are updated at any time;
3) To make the dimensionless variables defined with respect to absolute quantities.
where the constants νi, µi and Ui play almost the same role of h, k and U0, but this time are referred to each LU, i = 1,….,n, so that
νi are the ratios between the sum of all the perimeters of the impermeable barriers inside the i‐th LU and the perimeter Pi of the LU itself;
µi are the ratios between the sum of the perimeters of all the compact edified areas (those with lower BTC (0‐0.4)belonging to class A) inside the i‐th LU and Pi;
Ui are the ratios between the sum of the surfaces of all the edified areas inside the i‐th LU and Ai.
iiiiii MViMMcM )1()1(' −−−= ν
iiiiiii VUVVMV µ−−= )1('
maxi
i
MM
=iM
ii A
V iV=
The new PANDORA differential equations system:
The connectivity indexes cik between two LUs i and k, as well as the total connectivity index ci between the i‐LU and all its neighbors can be defined by the following formulas:
where Ii is the set of the neighbors of the i‐th LU.
c can be greater than one
LUi
LUk
LUkLUk
LUk
LUi
LUkLUk
LUkLUk LUi
LUk
LUk
LUkLUk
LUi
LUk
LUkLUk
LUk
LUi
LUk
LUk
LUkLUk
Once the variables Mi(t) and Vi(t) are known from the new equations, one can recover, at each time t, the
corresponding variables at the level of the whole environmental system; in particular the non-
dimensionless variablesM and V can be computed by
whereas the dimensionless ones M and V referred to the whole system are given by
Study case
Subset of 8 landscape units. The total area covered by urban sprawl is about 21% of the total urban area.Road and railway networks are highly developed (183.7 Km).A new stretch of the Orte-Civitavecchia freeway (dashed line) was completed during the year 2011 and it crosses the LU No.26.
Lazio Region
Traponzo watershed
Scenario analysisScenario A without the stretch of the freeway Orte-CivitavecchiaScenario B with the completed freeway (actual landscape)
The table shows the values of the model parameters for each simulated LU in the initial conditions. i.e. scenario A, without the last stretch of the free-way Orte-Civitavecchia that was completed during the year 2011. In this Table changed values referred to scenario B are reported between brackets.
LU Vi Mi Ui µi νi913142224262941
0.0000 0.044 0.689 1.317 1.8590.0317 0.191 0.014 0.084 0.2860.3895 0.423 0.013 0.222 0.8350.4329 0.457 0.006 0.005 0.5620.0335 0.206 0.021 0.909 0.5660.1604 (0.1601) 0.257 (0.256) 0.016 (0.017) 0.347 (0.746) 1.517 (1.956)0.0624 0.185 0.014 0.912 0.3410.2226 0.311 0.016 0.177 1.029
RESULTS and DISCUSSION
0 5 10 15 20 25 30 35 40 45 500
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2MV
0 5 10 15 20 25 30 35 40 45 500
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2MV
a) b)
0 5 10 15 20 25 30 35 40 45 500
0.05
0.1
0.15
0.2
0.25
0.3MV
0 5 10 15 20 25 30 35 40 45 500
0.05
0.1
0.15
0.2
0.25
0.3MVa) b)
Evolution trends of the variables V(t) and M(t) for LU n° 24: a) scenario A; b) scenario B.
Evolution trends of the variables V(t) and M(t) for LU n°26. a) scenario A; b) scenario B.
0 5 10 15 20 25 30 35 40 45 500
0.1
0.2
0.3
0.4
0.5
0.6
0.7MV
00 55 1010 1515 2020 2525 3030 3535 4040 4545 505000
0.0.11
0.0.22
0.0.33
0.0.44
0.0.55
0.0.66
0.0.77MMVVa)
Evolution trends of the variables V(t) and M(t) for the whole environmental system in scenario A (black lines) and scenario B (grey lines)
PANDORA2
PANDORA2 differential equations consider the time evolution of parameters and the feedback effects between them.To better understand the complex mechanism of cause and effect underlying landscape evolution dynamics, a holistic approach should be pursued, but local critical status of landscape health can be pointed out recurring to the simulation of the evolution of the global variables at local level, namely at the level of each LU.
PANDORA2 can provide a reliable tool to estimate the effects of actions and strategies on the landscape equilibrium conditions not only at the whole landscape scale but also at that of each LU.
Local critical values of the variables chosen to describe the health of the landscape can be pointed out only recurring to the simulation of the evolution of the same variables at local level, at the level of each Landscape Unit.
The parameters and indices of the model can suitably represent the ecological health of the landscape and can be used alone or in combination to assess and compare landscape scenarios.
Further effort is needed to accurately test this new dynamical model to real-life applications assessing its sensibility in order to develop a more helpful tool for “what if " scenarios analysis and planning strategy conception.
CONCLUSIONS
Thank you very much!
Raffaele Pelorosso