A Comparison of Methods for Measuring Effects of Density and Proportion in Plant Competition Experiments

Roush, Mary Lynn; Radosevich, Steven R.; Wagner, Robert G.; Maxwell, Bruce D.; Petersen, Terry D.

doi:10.1017/s0043174500071897

Cited by 99 publications

(67 citation statements)

References 12 publications

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“…High intraspecific and interspecific competition of potato clearly suggests that potato plants have captured environmental resources more efficiently than common bean plants. Roush et al (1989) also reported that NDI was smaller than 1 for wheat and ryegrass intercropping. In contrast, Raey et al (2005) in soybean and shatter cane interference and Passini et al (2003) in Alexander grass and common bean competition reported that NDI was greater than 1.…”

Section: Discussionmentioning

confidence: 94%

“…Roush et al (1989) compared three approaches to describe competitive interactions between wheat and Italian ryegrass. These comprised conventional analysis of replacement series experiments, development of synthetic no-interaction responses from monoculture experiments for comparison with results from mixedculture, and responses of the reciprocal yield of individual plants to variation in densities of the two species.…”

Section: Introductionmentioning

confidence: 99%

“…When the inverse of individual plant weight is used as the dependent variable, the relationship of plant density to plant weight becomes linear and the regression coefficients that define the slope of the line quantitatively describe the importance of intraspecific and interspecific competition density effects on individual plant weight of the species in question (Roush & Radosevich 1985). These coefficients can be used to calculate the relative competitive abilities of each species being studied (Roush & Radosevich 1985;Oliver & Buchanan 1986;Roush et al 1989). Raey et al (2005) improved these equations to quantify the relationship of soybean grain yield with different densities of soybean and shatter cane.…”

Section: Introductionmentioning

confidence: 99%

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Yield‐density relationship for potato (Solarium tuberosum) and common bean (Phaseolus vulgaris) in intercropping

Raey¹,

Ghassemi‐Golezani

2009

New Zealand Journal of Crop and Horticultural Science

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Methodologies of competitive interaction quantification between crops are not widely investigated. Therefore, field experiments (using addition series) were conducted in 2005 and 2006, to quantify interspecific and intraspecific competition coefficients and, also, the relative competitive ability (RC) of potato (Solanum tuberosum) and common bean (Phaseolus vulgaris). The relations between potato tuber yield/plant and common bean density at various densities of potato and also with potato density at different densities of common bean are well described by the reciprocal equations. Potato tuber yield/unit area decreased as common bean density increased. Optimum potato densities on the basis of maximum potato tuber yield/unit area at 0, 20, 30, and 40 plants/m 2 of common bean were obtained at 14, 13, 12, and 12 plants/m 2 , as estimated by the parabolic relations between potato tuber yield/ unit area and potato densities at different common bean densities. Potato was a stronger competitor than common bean, as a potato plant was equal to 6.22 common bean plants, based on potato tuber yield. A common bean plant, also, was equivalent to 0.0475 of a potato plant, on the basis of common bean grain yield. Therefore, potato was more aggressive than common bean, indicating that potato tuber yield was mostly affected by intraspecific competition, whereas common bean grain yield was mostly affected by interspecific competition. Niche differentiation index (NDI) was smaller than 1, showing severe competition of two species for environmental H08057; resources. It was concluded that yield-density relations in intercropping could be well quantified by application of the proposed equations.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Yield‐density relationship for potato (Solarium tuberosum) and common bean (Phaseolus vulgaris) in intercropping

Raey¹,

Ghassemi‐Golezani

2009

New Zealand Journal of Crop and Horticultural Science

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“…This wider spacing resulted in the same density of each species as the 0.5:0.5 species proportions for the mixed stands when planted on the 3 m × 3 m grid. Thus, the monoculture treatments at the widest spacing (4.2 m × 4.2 m) can be compared with 0.5:0.5 species proportions at 3 m × 3 m spacing and also allow an assessment of the effect of other densities on the outcome of the species association (Jolliffe et al 1984;Firbank and Watkinson 1985;Roush et al 1989). …”

Section: Experimental Designmentioning

confidence: 99%

Effects of species mixtures on growth and stand development of Douglas-fir and red alder

Radosevich¹,

Hibbs²,

Ghersa³

2006

Can. J. For. Res.

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In the Pacific Northwest, a mixture of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnus rubra Bong.) often results when red alder regenerates naturally in planted conifer stands. The relationships among stand structure, tree mortality, tree size, and understory development in the two species mixtures were explored at two sites for the first 16 years after planting. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or planting was delayed for 5 years. Red alder was also removed from some simultaneously planted proportions. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of the interaction were considered. Red alder grew relatively better at Cascade Head Experimental Forest in the Coast Range, while Douglas-fir grew better at H.J. Andrews Experimental Forest in the less temperate Cascade Mountains. Possible production benefits from mixed plantings were examined using two methods of calculation. Potential production benefits from certain planted proportions of the two species occurred at H.J. Andrews Experimental Forest. No planting time or species proportion resulted in yield improvements over monoculture stands at Cascade Head Experimental Forest. Understory species also varied because of differences in site and stand characteristics that resulted from the differences in planting times and species proportions.Résumé : Dans la région nord-ouest du Pacifique, des peuplements mixtes de douglas de Menzies (Pseudotsuga menziesii (Mirb.) Franco) et d'aulne rouge (Alnus rubra Bong.) se constituent souvent lorsque l'aulne rouge se régénère naturellement dans des plantations de conifères. Les relations entre la structure du peuplement, la mortalité des arbres, les dimensions des arbres et le développement de la végétation sous un couvert composé de différentes proportions des deux espèces ont été étudiées dans deux stations au cours des 16 premières années suivant la plantation. Les traitements incluent plusieurs combinaisons des deux espèces dans différentes proportions et la plantation soit simultanée, soit décalée de 5 ans, de l'aulne rouge. L'aulne rouge a aussi été éliminé de certaines combinaisons où les deux espè-ces avaient été plantées simultanément. Tant les effets de remplacement (la densité totale du peuplement est maintenue constante) que les effets additifs (la densité du peuplement est doublée) de l'interaction entre les deux espèces ont été pris en compte. La croissance de l'aulne rouge était supérieure à la forêt expérimentale Cascade Head dans la chaîne côtière alors que celle du douglas de Menzies était meilleure à la forêt expérimentale H.J. Andrews soumise au climat plus rigoureux de la chaîne des Cascades. Les gains potentiels de production des plantations mixtes ont été étudiés selon deux méthodes de calcul. Des gains potentiels de production ont été réalisés à la forêt expérimentale H.J. Andrews avec certaines proportions des deux espèces. Ni le moment d...

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“…Experiment designs that allow the full implementation of the RGRD method include those that have been proposed for response surface estimation (e.g. Connolly 1987;Rejma´nek et al 1989;Roush et al 1989;Snaydon 1991;Turkington and Jolliffe 1996;Gibson et al 1999;Goldberg and Scheiner 2001;Inouye 2001).…”

Section: Discussionmentioning

confidence: 99%

Assessing determinants of community biomass composition in two-species plant competition studies

Connolly

Wayne

2004

Oecologia

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A method is proposed for assessing the relative importance of species identity, neighbour species influence and environment as determinants of change in community biomass composition in two-species short-term competition experiments. The method is based on modelling the differences in relative growth rates (RGR) of species (hence called the RGRD method). Using a multiple regression approach it quantifies the effects of initial species' abundance, species identity and environment on RGRD and hence on change in community biomass composition. The RGRD approach is relatively simple to use and deals readily with statistical difficulties associated with correlated responses between species from the same stand. It can be easily adapted to analyse sequential harvest data. An example based on data from two-species mixtures of the annual species Stellaria media and Poa annua is used to illustrate the method. The main determinant of change in community biomass composition was species identity, reflected in the difference in growth rates between the species. Change in community composition was not, in general, significantly affected by the influence of neighbours or fertiliser level. The unimportance of the influence of neighbours in affecting the composition of these communities contrasts with the strong role of intra- and interspecific competition in determining the size of individuals of both species (Connolly et al. in Oecologia 82:513-526, 1990).

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A Comparison of Methods for Measuring Effects of Density and Proportion in Plant Competition Experiments

Cited by 99 publications

References 12 publications

Yield‐density relationship for potato (Solarium tuberosum) and common bean (Phaseolus vulgaris) in intercropping

Yield‐density relationship for potato (Solarium tuberosum) and common bean (Phaseolus vulgaris) in intercropping

Effects of species mixtures on growth and stand development of Douglas-fir and red alder

Assessing determinants of community biomass composition in two-species plant competition studies

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