Weeds in <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> subsp. <Emphasis Type="Italic">maidenii</Emphasis> (F. Muell) establishment: effects of competition on sapling growth and survivorship |
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Authors: | A M Garau C M Ghersa J H Lemcoff J J Barañao |
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Institution: | 1.Cátedra Dasonomía, Depto. Producción Vegetal, Facultad de Agronomía,Universidad de Buenos Aires,Buenos Aires,Argentina;2.IFEVA, Depto. Recursos Naturales y Ambiente, Facultad de Agronomía,Universidad de Buenos Aires,Buenos Aires,Argentina;3.Institute of Soil, Water and Environmental Sciences,The Volcani Center, Agricultural Research Organization,Bet Dagan,Israel;4.Departamento de Tecnología, Facultad de Agronomía,Universidad Nacional de Luján,Luján,Argentina |
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Abstract: | The effect of herbaceous vegetation on growth and survival was assessed in planted eucalyptus saplings grown under four levels
of weed cover. Seedlings of Eucalyptus globulus subsp. maidenii were planted with 0 (W0), 25 (W25), 50 (W50) and 100% (W100) weed cover. Weed species composition and aboveground biomass
was determined. Soil water content was evaluated by the gravimetric method. Seedling leaf area, diameter and height were evaluated
at planting and during the 3 months following establishment. Tree height, diameter and stem volume was estimated at 12, 24
and 36 months. First year tree survival was recorded. The ratio of cumulative stem growth under W100: cumulative stem growth
under W0 was used to measure competitive performance. Regression analysis was used to determine competition thresholds. Weeds
seriously threaten the growth of E. globulus subsp. maidenii. Early negative effects of competition on growth were evident as from the second month after establishment, and both seedlings
and 1-year-old saplings were more affected than 2- and 3-year-old ones. A “minimum-response threshold” was determined near
500 kg/ha (corresponding to W25 cover). No clear effect was found between sapling survival and weed biomass. |
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Keywords: | Eucalyptus Establishment Weed competition Competition threshold Competitive performance |
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