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Landforms and the shaping of cultural landscapes in mountain areas A methodology for the analysis of permanent pastures landscape of Alto Barroso region (Northern Portugal)

17th International Symposium “Landscape and Landscape Ecology”27 – 29 May, 2015, Nitra, Slovakia

Andreia Pereira – andreiaflup@gmail.com Phd student in Physical Geography in the University of Coimbra /

Centre of Studies on Geography and Spatial Planning (CEGOT), Portugal

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Research goals

Analyse how major terrain features and medium scale landforms, as well as the lithological formations, played a key role in the organization of the

soil use pattern in Alto Barroso

Identify and characterize the landforms with major interest for

landscape interpretation

Define the conditions of the distribution of the different types of

permanent grasslands, with particular emphasis in the morphostructural

factors

Promote the acknowledgment of the landscape and productive values of

the landforms and their potential heritage interest

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LandformHistorical /cultural / economical value

Scientific / didactic value

Results from the

combination of geo-

structural and

morphogenetic factors

Conditioning factor Testifies

Land-use options and strategic use of

resources

Functional appropriation of the

resources associated to landforms

Morphogenetic processes that took

place in paleoenvironments,

the tectonic action and the present dynamics

Understanding of geomorphological heritage as a an

evidence from the past and present

geomorphologic processes

Understanding of geomorphological

heritage as an evidence of Man – Nature interactions

Landforms are a crucial variable in land planning, territory management and development strategies

Dimensions and values of the geomorphologic heritage

Alto Barroso: morphostructural framework

Climograph of Montalegre

Pre

cipi

tatio

n (m

m)

Tem

pera

ture

(ºC

)

Temperature (ºC)Precipitation (mm)

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What defines the landscape character in Alto Barroso?

Morphological features of a table land• Importance of the plateaus, entrenched valleys, grabens and natural terraces in the distribution of the

soil uses

Specific characteristics of a multi-century old agro-pastoral system• Cattle breading, based on extensive grazing, as the main regional production• Cultivation of poor dryland cereals at high altitudes• Association of poor mountain pastures and water-meadows (semi-artificial permanent grasslands)• Introduction of the water-meadows during the Upper Medieval Ages, simultaneously with the creation

of the mountain villages (Moreira et al. 2001; Taborda 1932)• Ancestral agro-pastoral techniques and practices (surface irrigation, grasslands in terraces,

communitarianism)• Preserved groves of broadleaves, especially oaks• Delimitation of the pastures by broadleaves

Concentrated settlement • Share of collective structures (threshing floors, oil mills, ovens) • Vernacular architecture• Use of local construction materials

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Agro-silvo-pastoral cultural landscape: a dynamic system • The morphological profile of a typical slope in Alto Barroso corresponds to

a specific pattern of distribution of land uses, whose sequence in altitude is determined by the variation of soil properties, water availability and slope.

• The forest and shrublands, the poor mountain pastures, the water-meadows, the upland cereal cultures and the extensive horticulture build a landscape mosaic sustained by an intricate network of functional interdependencies and complementarities.

Mountain grasslands and permanent pastures

Environmentalfunctions

Economic functions

Cattle Breeding (autochthonous bovines)

Regulation of the water cicle

Aestetic value

Increase of the diversity of landscape mosaic

Past Present

Labour force Bovine meat of high quality

Manure

Seed potatoes

Upland Cereals

Watering crops Fauna and flora biodiversity

Soil formation and protection

Control of wildfires spread

Tourism Resource

Infiltration / Accumulation

Recharging of the groundwater tables

Decrease of the soil erosion risk

Decrease of pipkrakes formation

LandscapeValue

Pastures

A cultural landscape that reflects the adaptation strategies to environmental constraints• The need to overcome the specific soil and climatic constraints of

mountain environments, aiming to enable the practice of agriculture and increase its productivity, led to the development of several strategies of water management and soil conservation, among which we must highlight:– the agro-pastoral terraces, with or without supporting walls; – the traditional irrigation systems, the practice of specific techniques

of “superficial irrigation” (“rega de lima”);– The incorporation of manure in the grasslands;– The communitarian management of some resources (irrigation water,

common lands) and agro-pastoral activities (shepherding), and structures / equipments

Sampaio (1979) states that in the Barroso "... the pastoral regimen becomes so prevalent that, without exaggeration, one can say that the population lives mainly of the herds, which in a large part of the year are breed in the rich pastures of the hills and the collective use of the neighbors".

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“Rega de Lima”• “Rega de Lima” is an ancient watering technique that is

based in a drainage system used to channel the water from small streams to slope ditches (locally named “regueiras”), following the contour lines.

• These ditches drain the irrigation water to the grasslands, allowing it to slowly flow over the soil trough a controlled runoff, producing a “lime effect”.

• Then, the ditches placed in a lower level collect the flowing water, reproducing the same process. In a final stage, the water returns to the stream.

• It is frequently observed the presence of a network of draining grooves linked to the ditches system, which enables a more uniform distribution of the water, preventing dry or flooded areas.

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Methodology• The assessment of potential geomorphological heritage was

conducted at a regional scale, within the framework of Alto Barroso;

• The main selection criteria reflects the relation between landforms and landscape structure.

Geomorphological analysis

• Field work• Morphostructural outline• Identification of the major terrain features and medium scale landforms

Homogeneous terrain units

• Morphologic factors• Morphodynamics• Landscape Perception•Adaptation of the geomorphological map to landscape reading

Correlation of landforms with the soil use pattern

• Distribution of the different types of permanent grasslands,

• Interrelation between the geomorphology and the landscape organization

Selected landforms: insertion in the regional morphology

Lithological diversity

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Morphostructure, landforms and soil use

Complementarity between different types of grasslands

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Water-meadows: location factors• Water-meadows occupy preferentially fields with high water

availability and fine textured soils with elevated organic matter content which, when soaked and with no vegetation cover, are abundant in mud, which will feature at the origin of the designation as "lameiros", a word that refers to a muddy grassland (Vieira et al., 2000; Pereira & Sousa, 2005).

• Therefore, they occur mainly on granitic substrates and on hillsides with slopes that goes from smooth to average gradient, so as to ensure a good drainage.

• The high amount of annual rainfall, associated with deep granitic alteration mantles, explain the great water availability, constituting a favorable factor to the implementation of water-meadows.

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Distribution of the permanent pastures over the main lithological groups

Lithological groups

Area (Km2)Area of the permanent

pastures Km2

% in relation to the total area of permanent

pastures

% of occupation of

the permanent pastures of the

area of the lithological

group

Granitic rocks 541,99 203,78 53,83 37,59

Schales 385,09 116,48 30,77 30,25

Paragnaiss 100,54 55,53 14,67 55,23

Others 37,16 2,75 0,73 7,40

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Percent of the soil use calculated in relation to the area of each landform

A Water-meadows; B Poor mountain grasslands; C Forest and shrublands; D Shrubby and sub-shrubby vegetation; E Scarce vegetation cover; F Complex agricultural areas; G Permanent cultures; H Annual cultures; I Built area.

Soil use area in %Landforms A B C D E F G H I

Valley of Aires River 32,9 28,7 15,6 15,6 0,0 1,4 0,0 5,4 0,1Upper Valley of Rabagão

River 43,7 16,6 2,77 16,3 2,7 9,7 0,1 4,4 3,4

Upper Valley of Cávado River 43,5 19,6 10,8 11,4 1,6 5,3 0,0 6,3 1,2

Upper Valley of Beça River 50,1 14,4 3,0 17,7 0,1 7,5 0,0 6,9 0,03

Middle Valley of Beça River 19,0 40,7 17,6 12,9 0,0 8,0 0,1 1,6 0,0

Lower Valley of Beça River 48,7 13,1 17,2 7,33 0,0 10,2 0,0 1,7 1,4Upper Valley of Assureira

River 33,0 2,4 10,2 8,1 26,2 6,6 0,0 12,1 1,1

Graben of Rabagão 27,3 12,8 15,0 10,6 0,6 4,2 0,0 27,4 1,7Graben of Dornelas 25,2 11,0 8,5 9,5 0,2 30,0 0,0 9,1 6,3Graben of Boticas 14,3 1,7 16,1 2,1 0,0 35,2 0,0 0,0 30,4Graben of Ardãos 30,5 14,4 7,2 13,6 0,00 24,4 0,0 6,9 2,8Graben of Amial 36,9 20,1 12,3 2,3 3,1 8,1 0,0 14,6 2,4Range of Seixa 3,4 6,1 39,7 43,3 3,8 2,1 0,0 0,4 0,8Range of Leiranco 0,2 15,4 2,2 79,9 0,9 0,4 0,0 0,1 0,5Range of Larouco 0,9 6,1 2,1 21,4 68,3 0,9 0,0 0,1 0,0Range of Cerdeira 7,3 19,4 18,7 45,1 1,8 2,0 0,0 4,9 0,4Range of Barroso 5,8 7,1 2,7 61,7 20,5 1,5 0,0 0,4 0,0Plateau of Pitões 11,0 44,4 5,6 30,7 4,9 1,2 0,0 1,8 0,3Plateau of Alturas 34,6 28,9 6,4 19,6 1,3 3,4 0,1 5,3 0,4Natural terrace of Solveira 10,5 18,9 2,5 20,5 4,8 5,1 1,5 35,0 2,2

Natural terrace of Pinho 11,0 0,1 29,5 26,9 0,00 30,1 0,0 0,3 1,9

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Landforms and the distribution of permanent grasslands and croplands

• Landforms may be divided in three groups according to the importance of the water-meadows and the poor mountain grasslands:1st - landforms with more than 50% of their area

occupied by permanent grasslands. In this group the valleys and uplands are dominant. Only the graben of Amial is inserted here.

2nd - landforms with 25% to 50% of their area occupied by permanent grasslands. In this group, the grabens are more representative.

3rd - the permanent grasslands represent less than 20% of the area of the landform. Here, there is a clear dominance of the mountain and hilly areas.

Contrast between the upper valley of Cávado river and the plateau of Pitões

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Morphological characterization of each landform and its relation with

soil use

LandformAreaKm2

Morphologic features

Main morphogenetic

process

Most relevant soil uses

Upper Valley of Rabagão River 43,02

Slope <8º; Minimum elevation - 870; Maximum elevation - 1168

Fluvial dynamicsProbably tectonic action at the northern sector leading to the formation of a graben.

Water-meadows: 43,75% Mountain grasslands 16,69% Low shrubs 16,36%

Upper Valley of Cávado River 33,63

Slope <11º; Minimum elevation - 750; Maximum elevation - 1021

Fluvial dynamicsFracture valley corresponding to a complex tectonic depression (graben)

Water-meadows 43,52% Mountain grasslands 19,67%

Valleys: clear dominance of water-meadows

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Grabens: dominance of water-meadows and croplands

LandformAreaKm2

Morphologic features

Main morphogenetic

process

Most relevant soil uses

Graben of Amial

7,76Slope <8º; Minimum elevation - 810; Maximum elevation - 930

Tectonic depressionWater-meadows 36,91%Mountain grasslands 20,16%

Graben of Rabagão

4,27Slope <11º; Minimum elevation - 700; Maximum elevation - 810

Tectonic depressionFluvial dynamics

Water-meadows 27,34% Annual cultures 27,45% Forest/shrublands 15,03%

Graben of Dornelas

3,12Slope <8º; Minimum elevation - 650; Maximum elevation - 734

Tectonic depressionWater-meadows 25,29%Complex agricultural systems 30,00%

LandformAreaKm2

Morphologic features

Main morphogenetic

process

Most relevant soil uses

Plateau of Pitões

96,12Slope 2º-11º;

Minimum elevation - 900; Maximum elevation - 1401

Complex horst; Fluvial dynamics

associated to fracture valleys

Mountain grasslands 44,47% Low shrubs

30,79%

Plateau of Alturas

60,93Slope <11º; Minimum

elevation - 810; Maximum elevation - 1229

Tectonic action leading to a elevated block (horst)

Fluvial dynamics

Water-meadows 34,60% Mountain grasslands 28,90% Low shrubs

19,61%

Plateaus: dominance of mountain grasslands, water-meadows and low shrubs

Relation between the landforms and the distribution pattern of the permanent grasslands• The water-meadows and the poor mountain grasslands

have more than a half of their area concentrated within the identified landforms. This strong correlation has no parallel when we look to the other soil uses: none of them reaches 50%.

• The water-meadows are predominantly located on valleys and grabens, as well as in plateaus when the hydrogeological and pedologic conditions are appropriated.

• The highest percent of the area of water-meadows at a regional scale is distributed by the plateau of Alturas, the upper valleys of the rives Rabagão, Cávado and Beça and the graben of Amial.

• The plateau of Pitões is the landform that concentrate the biggest area of poor mountain grasslands, followed by the plateau of Alturas.

From the relation landforms/landscape to the selection of geomorphosites• The upper valleys of Cávado, Rabagão and Beça rivers, the

plateaus of Pitões and Alturas and the graben of Amial proved to be the landforms that conciliate a greater landscape and productive values.

• They may be classified as sites of geomorphological interest at a regional scale, which heritage value should be protected, by the inclusion of preservation measures in the territorial management instruments, by monitoring land use changes and its drivers, as well as by encouraging the maintenance of the traditional cattle breeding practices.

• This approach highlights the heritage value of eco-sociologic systems that express multi-century old strategies of Man adaptation of environmental conditions and promote its use as a differentiation factor in sustainable development marketing (local products certification with Protected Designation of Origin / Protected Geographical Indication; cultural and landscape touring.)

Be welcome to Alto Barroso!