42 PEDRO MONTSERRAT and FEDERICO FILLATbaAtlanticOceanaCordilleraIbérica~+-~--r +"Macizo Hespérico"PyreneesEbro ~Valle~.\'bW Spa<strong>in</strong>"Alcarria""Síerras"E Spa<strong>in</strong>e+ +d(A)PastureCrest ~-='r:-:¡=Fores tHeadowsRiverCulture(E)Glacis:. 1 •••• 6" • " •Fluvial terracesPig. 3.4. A. The ma<strong>in</strong> lopographical [catmes <strong>of</strong> Lhe Pen<strong>in</strong>sula. a-b is a cross-section from Portugal to <strong>the</strong> Pyrenees, c-d is a crosssectionfmm Ihe Meseta lo lhe Mediterranean Sea; lhe gcomorphological names <strong>in</strong> Spanish are puL on lhe draw<strong>in</strong>g. n. Typical slopewilh lopographical sequences.
THE SYSTEMS OF GRASSLAND MANAGEMENT IN SPAIN43ancient socIe l and its recent üligocene orogeny isvery rich <strong>in</strong> lime and flysch.The great "Macizo Hespérico"2 <strong>of</strong> CaledonianHercynian orogeny presents an overall homogeneityexcept at <strong>the</strong> extreme edges where MesoCenozoic mounta<strong>in</strong>s are found (Montes Cantábricos,Montes Ibéricos, Sierras Béticas). It is a horstlimited by a system <strong>of</strong> faults to <strong>the</strong> nor<strong>the</strong>ast (<strong>the</strong>Ebro Bas<strong>in</strong>) and south (<strong>the</strong> Guadalquivir Bas<strong>in</strong>).Duúng <strong>the</strong> Miocene, <strong>the</strong> Pliocene and at <strong>the</strong>present time, evaporites have been laid down <strong>in</strong> <strong>the</strong>Ebro Valley (dry with strong W-NW w<strong>in</strong>ds), <strong>in</strong>Castilla and La Mancha. The endorheic bas<strong>in</strong>swere <strong>of</strong> less importance <strong>in</strong> <strong>the</strong> Guadalquivir Bas<strong>in</strong>but <strong>the</strong>y are still to be found <strong>in</strong> <strong>the</strong> great mounta<strong>in</strong>ranges <strong>of</strong> <strong>the</strong> sou<strong>the</strong>as!. The tilt<strong>in</strong>g <strong>of</strong> <strong>the</strong> Meseta,comb<strong>in</strong>ed with partial subsidence on <strong>the</strong> Atlanticside (Rías gallegas), dra<strong>in</strong>ed Castilla and LaMancha, reduc<strong>in</strong>g endorheism but re-activat<strong>in</strong>gerosion along <strong>the</strong> Iberian edge, with <strong>the</strong> consequentrenewal <strong>of</strong> soHs and <strong>the</strong> expansion <strong>of</strong>gypsophilic communities.TopographieaI mieroelimatesOn mounta<strong>in</strong> slopes microclimate varies accord<strong>in</strong>gto <strong>the</strong> degree <strong>of</strong> exposure to sunsh<strong>in</strong>e and <strong>the</strong>type <strong>of</strong> prevail<strong>in</strong>g w<strong>in</strong>ds. They can be ascend<strong>in</strong>gw<strong>in</strong>ds, with <strong>the</strong> formation <strong>of</strong> mist or descend<strong>in</strong>gfoehn w<strong>in</strong>ds. When <strong>the</strong>re is a channell<strong>in</strong>g <strong>of</strong> w<strong>in</strong>d(Venturi elfect) it causes drought <strong>in</strong> certa<strong>in</strong>localized spots (this is <strong>of</strong>ten caused by descend<strong>in</strong>gw<strong>in</strong>ds). Each type <strong>of</strong> microclimate favours adilferent k<strong>in</strong>d <strong>of</strong> plant growth, and as a result <strong>the</strong>flora <strong>of</strong> <strong>the</strong> Iberian Pen<strong>in</strong>sula is very rich. Beeause<strong>of</strong> <strong>the</strong> mounta<strong>in</strong>-valley sequenees already mentioned,drought conditions can be found even <strong>in</strong>environments with a wet oceanic type <strong>of</strong> c1imatc.This is a source <strong>of</strong> diversity, with prcservation afvery particular plants, and also eaus<strong>in</strong>g greatspeeialization <strong>in</strong> pasture <strong>management</strong> (see alsoMontserrat, 1980, 1981, 1983).Thc dynamies <strong>of</strong> waterAs mentioned aboye, <strong>the</strong> prcsence <strong>of</strong> water¡nfluenees temperature due to its high specifie andlatent hea!. Water also causes erosion throughfreez<strong>in</strong>g-thaw<strong>in</strong>g, imbib<strong>in</strong>g-dry<strong>in</strong>g out· and runolf.On <strong>the</strong> o<strong>the</strong>r hand, <strong>in</strong> its role as transportagent, it eontributes to fertilization and facilita tesplant reeuperation. The topography, frequency <strong>of</strong>mists, water-vapour condensation under ground,etc., all <strong>in</strong>Ouence <strong>the</strong> dynamism <strong>of</strong> pasture-Iands,as do both erosion and rapid soi] reeovery.Erosion is a process which liberates soil-enrich<strong>in</strong>gnutrients, <strong>the</strong> loss <strong>of</strong> which is prevented by soilbacteúa aud <strong>the</strong> iutense root activity <strong>of</strong> certa<strong>in</strong>plants. This activity is greatest <strong>in</strong> luxuriant arcasbordeúng forest, <strong>in</strong> meadows, and espeeially where<strong>the</strong>re is a productive <strong>grassland</strong>. Watercourses havebeen changed to irrigate pasture-Iand, fodder eropsare grown where <strong>the</strong>y are appropriate to <strong>the</strong>surround<strong>in</strong>g environment, with an eye to choos<strong>in</strong>gspecies that resist unpredictable periods <strong>of</strong> dryness,and <strong>the</strong> herds are moved to places where <strong>the</strong>topographical microclimate is optimal. Plants,animals and human activities are a refiexion <strong>of</strong>climate,Watercourses and associated phenomena(Fig. 3.4B)Topographieal sequences on slopes are l<strong>in</strong>kedma<strong>in</strong>ly to geophysical characteústics like rockhardness, 01' to protection <strong>of</strong> <strong>the</strong> soil by plantsaga<strong>in</strong>st erosiono Deeper soils are found ma<strong>in</strong>ly onfluvial terraees and glacis, but also on slopes,cl/estas, protected by hard rocks (polycyc1ic relief)as <strong>in</strong> our scheme, obviously favour<strong>in</strong>g accumulation<strong>of</strong> soil, and <strong>the</strong> establishment <strong>of</strong> grasses andtrees, and caus<strong>in</strong>g great diversity <strong>in</strong> a restrictedspace.The rclationship between <strong>the</strong> animals and environmentis reciprocal; fOI example, mounta<strong>in</strong>tops are fertilized by animals <strong>in</strong> <strong>the</strong>ir search forcool w<strong>in</strong>dy areas where <strong>the</strong>y will not be plagued byflies. Although high mOllnta<strong>in</strong> erests are <strong>of</strong>tenlInproductive and stony, <strong>the</strong>y are never<strong>the</strong>less asouree <strong>of</strong> <strong>the</strong> water needed for lower mounta<strong>in</strong>pastnres.The deve!opment <strong>of</strong> <strong>the</strong> vegetation, transhumanee<strong>of</strong> animals and human activities have beenshaped by <strong>the</strong> variation <strong>of</strong> <strong>the</strong>se environments,form<strong>in</strong>g repetitive patterns which can be studied.S<strong>in</strong>ce snch diversity exists <strong>in</strong> Spanish valleys itmight be helpful to study some examples which willenable us to nnderstand <strong>the</strong> general trends <strong>of</strong>lThc Axial Pyrenecs formed dur<strong>in</strong>g Hercynian orogeny.2The olclest part <strong>of</strong> <strong>the</strong> Ibccian Pen<strong>in</strong>sula.
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