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PARAMOS

PARAMOS The “paramos” constitute both a region and a vegetation type in the high equatorial Andes of northern South America (Ecuador, Colombia and Venezuela) (Vareschi 1988).

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PARAMOS

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  1. PARAMOS The “paramos” constitute both a region and a vegetation type in the high equatorial Andes of northern South America (Ecuador, Colombia and Venezuela) (Vareschi 1988). They occur above 2,800 m elevation, and are characterized by highly diversified, complex genus Espeletia (Asteraceae), with life forms similar to those found within other genera of the same family in the Kilimanjaro (Senecio), Hawaii (Argyroxiphium). This life form is described as a giant rosette, with leaves covered with a dense, whitish hair layer. Leaves are not shed during senescence but remain adpressed to the succulent stem (marcescent leaves), providing thermal isolation to the water conducting tissue (Goldstein et al. 1991). Plants in this tropical alpine environment show adaptations to high irradiation, extreme diurnal temperature oscillations, and seasonal dry conditions (Monasterio and Sarmiento (1991).

  2. Paramos: 10º N, 67W

  3. Squeo F.A., Rada F., Azócar A., Goldstein G. (1991) Freezing tolerance and avoidance in high tropical Andean plants: is it equally represented in species with different plant height? Oecologia 86: 378-382. Species Life-form Altitudinal distribution Arenaria jahnii Brake (Caryophyllaceae) cushion 2400-4350 Azorella julianii Math (Apiaceae) cushion 3500-4600 Lucilia venezuelensis Stmk. (Asterac.) cushion 3650-4300 Castilleja fissifolia L.f. (Scrophulariaceae) perennial herb 2000-4300 Geranium multiceps Tourez (Geraniaceae) perennial herb 3000-4200 Senecio formosus H.B.K. (Asteraceae) perennial herb 2800-4200 Draba chionophylla Blake (Cruciferae) small rosette 4300-4600 Espeletia moritziana Sch. Bip. (Asteraceae) giant rosette 3200-4400 Espeletia schultzii Wedd. (Asteraceae) giant rosette 2600-4300 Espeletia spicata Sch. Bip. (Asteraceae) giant rosette 3800-4300 Espeletia timotensis Cuatr. (Asterac.) giant rosette 4000-4400 Hinterhubera lanuginosa Cuatr et Arist (Asterac) shrub 3500-4200 Hypericum laricifolium Juess. (Guttiferae) shrub 2200-4200 Polylepis sericeus Wedd. (Rosaceae) small tree 2400-4600

  4. Summary of morphological and physical characteristics of five Espeletia schultzii populations occurring along an elevation gradient (after Meinzer and Goldstein 1985) Elevation (m) Pith volume Leaf area PV/LA Pubescence thickness Leaf absorptance (cm3) (cm2.104) (cm3 cm-2) (mm) 400-700 nm 2,600 (≈ 13ºC) 89 1.16 0.008 1.1 0.78 3,100 336 0.96 0.039 1.6 0.74 3,550 424 0.68 0.063 2.1 0.70 3,850 702 0.64 0.116 2.3 0.67 4,200 (≈ 2.8ºC) 873 0.48 0.179 2.6 0.69

  5. Site characteristics where Espeletia species were studied to estimate the period of time during which the water removed from the pith could replace the water transpired (T) (Meinzer and Goldstein 1986) Paramo site Annual Mean and elevation precipitation temperature Species PV/LA ∆M T Hours (m) (mm) (ºC) (cm3 cm-2) (g) (g h-1) of T Piedras Blancas 798 2.8 E. lutescens 0.105 176 70.7 2.5 4,200 E. moritziana 0.057 57 39.7 1.4 E. spicata 0.056 160 81.9 2.0 Mucubaji, 969 5.4 E. schultzii 0.047 99 95.2 1.0 3,600 E. floccosa 0.013 27 44.8 0.6 Batallon 1213 9.3 E. marcana 0.038 86 55.3 1.6 3,100 E. atropurpurea 0.018 9 16.3 0.6 Hours of transpiration were calculated by dividing the mass of available water in the pith (∆M) by the transpiration rate (T) of the entire rosette. Pith volume per unit leaf area (PV/LA) is a measure of relative capacitance

  6. Temperature for 50% injury, supercooling points, and relative apoplastic water content of leaves (3-5 pressure-volume curves) of 10 Espeletia species occurring along an altitudinal gradient. Leaf water potential range was -0.4 to -0.9 Mpa (after Goldstein et al. Oecologia 68:147-152.1985) Species Elevation Supercooling 50% injury Relative apoplastic (m) point ºC ºC water content % E. lindenii 2850 -7.5 -6.5 7.0 E. angustifolia 2850 -6.6 -6.1 35.8 E. atropurpurea 2850 -6.4 -5.9 26.2 E. marcana 3100 -9.1 -8.0 20.5 E. atropurpurea 3100 -7.3 -8.1 19.9 E. jahnii 3100 -5.7 -5.6 25.1 E. schultzii 3560 -10.8 -10.0 16.0 E. floccosa 3560 -8.5 -9.3 7.3 E. schultzii 4200 -10.0 -11.2 3.9 E. moritziana 4200 -10.6 -11.3 4.0 E. spicata 4200 -10.0 -9.5 7.4 E. lutescens 4200 -10.5 -10.2 2.2

  7. Relationship between cold injure temperature, and appearance of the first exhotherm for leaf tissues; n≥ 6 (modified from Squeo et al. Oecologia 86:378-382.1991) Species Temperatures ºC Cold resistance Life form Injury Freezing mechanism Espeletia moritziana -11.3 -10.6 Super Cooling Giant Rosette E. schultzii -12.0 -11.6 Super Cooling Giant Rosette E. spicata -11.3 -12.8 Super Cooling Giant Rosette E. timotensis -11.9 -11.7 Super Cooling Giant Rosette Polylepis sericea -8.0 -7.5 Super Cooling Small Tree Hinterhubera lanuginosa -12.3 -12.7 Super Cooling Shrub Hypericum laricifolium -10.9 -9.4 Super Cooling Shrub Senecio formosus -9.3 -3.5 Freezing Tolerance Perennial Herb Castilleja fissifolia -14.8 -4.1 Freezing Tolerance Perennial Herb Arenaria jahnii -18.8 -3.2 Freezing Tolerance Cushion plant Azorella julianii -10.6 -3.7 Freezing Tolerance Cushion plant Draba chionophylla -14.8 -5.0 Freezing Tolerance Small Rosette Lucilia venezuelensis -14.3 -4.4 Freezing Tolerance Cushion plant Cold injury measured with Triphenyl-tetrazolium chloride (Steponkus and Laphear Plant Physiology 42,1423.1967 Cold resistance mechanism: difference between injure temperature (IT) and freezing temperature (FT) (Larcher 1982) IT larger than FT---> freezing avoidance by insulation IT similar to FT ---> supercooling IT lower than FT ----> freezing tolerance

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