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Ecophysiology of Berberis darwinii Hook. in its native range

Abstract : Invasive exotic species' success may depend on ecophysiological attributes present in their native area (NA) or those derived from changes that took place in the invaded area (IA). Berberis darwinii is a shrub native to Argentina and Chile, and invasive in New Zealand. The ecological, ecophysiological and growth patterns of plants of this specie that present under different light conditions in temperate forests of southern Argentina were studied. The ecophysiological attributes of populations of B. darwinii of NA were compared with published data on populations of IA. In NA abundance of B. darwinii was studied in 39 plots (100x100m) in forests of the Nahuel Huapi National Park and compared to a set of environmental variables. Local abundance of the specie was compared in relation to conditions of gap, edge, and under the canopy of Nothofagus dombeyi at two sites at Victoria Island, one at Llao-Llao and Traful. On two of this sites, flowering and fruiting phenology, and reproductive success of B. darwinii was studied. Production of flowers and ripe fruits was analyzed periodically in five branches of ten plants per light environment. In these environments the viability of seeds, seed bank, germination, seedling survival, growth and biomass allocation were studied, determining the LAR (total fresh leaf area/total mass seedling), LMR (total leaf mass/total seedling mass), RMR (root mass/mass of stem + leaf), and SLA (total leaf fresh area/total leaf mass). In two sites were studied light effect on branches growth level in five plants per adult in each light environment, and in one site the photosynthesis. Also, was determinate the net photosynthesis as a function of photosynthetically active radiation, stomatal conductance (gs), the maximum rate of photosynthesis under saturating light (Pmax), photosynthesis based on leaf mass (Pmass), and water use efficiency (WUE). Finally, branching patterns were studied according to light in two sites. Locally, B. darwinii is a sunny specie adapted to intermediate light conditions only flowered in gap and edge forest, showing similar length of flowering and fruit ripening periods. Plant gap produce more racime per branch but fewer open flowers and ripe fruits per raceme, and a lower proportion of flowers that pass mature fruit in plants edge. The seed viability was over 90% and the seeds germinated in the spring in similar proportions in three light environments while seedling survival was similar. Under the canopy, seedlings produced longer stems and exhibited higher SLA and LAR, lower RMR, and similar MRL. Seedling mortality by herbivory was high on the edge and shade, and drying in the gap. Adult plants presents under the canopy produced the longer shoot and fewer buds and leaf biomass per shoot, while SLA was higher than in plants of the edge and the forest gap. The number of leaves and the stem biomass per shoot were independent of light. Gap plants showed higher values of Pmax, Pmass and gs but less WUE than the edge plants. B. darwinii produce long shoots (macroblast) and short shoots (braquiblast). The macroblast differed from a braquiblast producing simultaneous branching, and the braquiblast produce simultaneous or delayed branching. Some architectural traits are influenced by the environment, as the length and number of internodes by light availability but internodes length was variable. Comparing populations NA and IA, an advance of flowering and dispersion of ripe fruits in IA was observed with respect to NA, but fruit production was similar. Seed viability, germination and seedling field survival differed between NA and IA. Although seed viability was highest in NA, in both areas was high. Seeds do not remain in the soil seed bank. In the IA gap fewer seeds germinate than in NA, but there is greater seedling survival. Seedling mortality is higher in NA than in IA. The magnitude of almost all measured variables in seedlings is between one and two times higher than in NA, the seedlings reach larger sizes, especially in gaps. The photosynthetic activity of leaves in plants determined NA was similar to those reported in IA. In both areas, gap plants showed less WUE by its gs. SLA of shade plants was higher in IA than in NA. B. darwinii grown under different light conditions but adjusting their morphology and physiology. In the native range B. darwinii shows a morphological plasticity that allows it to grow along different environmental gradients. B. darwinii does not show a higher productivity level of seed availability in IA and therefore aspects of reproduction are conservative trait for the species. B. darwinii has not the ability to form part of the seed soil bank and build on it a large mass of seeds, as other invasive alien species. These differences could be due to the influence of environmental factors as changes of invasive species acquired in the area. B. darwinii plants growing in different light environments show similar physiology in their native and invasive ranges. This means that for B. darwinii, intraspecific variation of functional traits studied is not an indicator of the success of invasion into new areas.
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Submitted on : Wednesday, February 17, 2021 - 11:26:10 AM
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  • HAL Id : tel-03144007, version 1

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Maya Svriz. Ecophysiology of Berberis darwinii Hook. in its native range. Systematics, Phylogenetics and taxonomy. Universidad Nacional del Comahue, 2015. English. ⟨tel-03144007⟩

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