Ecological and ecophysiological patterns in a pre-altiplano shrubland of the Andean Cordillera in northern Chile |
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Authors: | PW Rundel AC Gibson GS Midgley SJE Wand B Palma C Kleier J Lambrinos |
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Institution: | (1) Department of Organismic Biology, Ecology and Evolution, University of California, Los Angeles, 90095, USA;(2) Kirstenbosch Research Center, National Botanical Institute, Claremont, 7735, South Africa;(3) Department of Horticulture, University of Stellenbosch, South Africa;(4) Casa Central, Universidad de las Americas, Manuel Montt 948, Providencia, Santiago, Chile;(5) Present address: Department of Biology, Adams State College, Alamosa, USA;(6) Present address: Graduate Program in Ecology, University of California, Davis, 95616, USA |
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Abstract: | We report on community structural, ecophysiological, phenological, and morphological measurements made on woody plant species
in the high elevation pre-altiplano zone on the western slopes of the Andean Cordillera of northern Chile. Notwithstanding
extreme conditions of low rainfall, high atmospheric vapour demand and diurnal temperature fluctuation, a diversity of habitats
(associated with drainage and slope aspect), appreciable local plant species richness (28 woody perennial plant species in
a small area), and an array of adaptive morphological ecophysiological and phenological traits are present among woody species
in these shrublands. Family diversity was low with four families accounted for 82% of the species. A range of gas exchange
and watering use efficiency strategies was present ranging from highly efficient CAM species with a carbon isotope discrimination
(Δ) of 3.7–7.5‰ through C3 species with varying stomatal and gas exchange characteristics with a Δ of 14.4 to 19.8‰. Drought-deciduous small-leaved
amphistomatic species from arid slopes generally had high stomatal conductance and high carbon assimilation rates during the
rainy season. These drought deciduous species were largely leafless and, with one exception had low water potentials, during
the dry season. Wash and less xeric site species commonly had broader evergreen to semi-evergreen leaves, higher dry season
water potentials, and relatively consistent and moderate rates of gas exchange throughout the year. For all species, intrinsic
water use efficiency (as estimated from the inverse of c
i
:c
a ratio) correlated positively with mean leaf width (broader leaves had a lower higher intrinsic WUE) and dry season water
potential. The charismatic high altitude tree, Polylepis rugulosa (Roaceae), had a population structure that suggests highly episodic establishment of seedlings, likely in sequences of wet
years. Little of the area of these significant shrublands is currently protected. It would be desirable to add areas of pre-altiplano
shrublands to adjacent national parks to ensure the persistence of these important communities.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | Carbon isotope discrimination Desert plants Drought deciduous leaves Photosynthesis Puna Water use efficiency |
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