Clipping Effects on Root Architecture and Morphology of 3 Range Grasses

Arredondo, J. T.; Johnson, Douglas A.

doi:10.2307/4003209

Cited by 23 publications

(23 citation statements)

References 37 publications

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“…Festuca rubra had the largest specific root length (SRL) and Fa the smallest, in agreement with earlier studies showing that species from nutrient poor environment generally have a higher SRL and relatively more fine roots (Berendse and Elberse 1990;Boot and Mensink 1990). Arredondo and Johnson (1998) found that root branching was unaffected by defoliation in a grazing tolerant species, while it increased the number of laterals in a grazing sensitive species. None of the current species showed increased branching with increased defoliation intensity, possibly because they were already well adapted to the repeated defoliation procedure.…”

Section: Discussionsupporting

confidence: 86%

Responses of plant traits of four grasses from contrasting habitats to defoliation and N supply

Gastal

Dawson

Thornton

2010

Nutr Cycl Agroecosyst

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The objective of the study was to identify specific plant traits determining adaptation of grass species to defoliation and N availability, and thus having a major impact on species dynamics, primary productivity, and on nutrient cycling in grassland ecosystems. It was specifically examined whether the response of species to defoliation is related to their plasticity in leaf growth and in leaf growth zone components, and whether the response of species to nitrogen is related to their plasticity in root morphology and subsequent N acquisition, and to N losses through leaf senescence. The study was conducted on L. perenne and D. glomerata, two grazing tolerant species from fertile habitats, and on F. arundinacea and F. rubra, two less grazing tolerant species from less fertile habitats. Plants were subjected to repeated defoliation at three cutting heights under both high N and low N supply. Biomass allocation, leaf elongation, characteristics of the leaf growth zone (height and relative growth rate), and root morphology, N uptake and N losses through leaf senescence were evaluated. Under high N supply, L. perenne and D. glomerata showed the greatest tolerance to defoliation, due to a large plasticity in the height of the leaf growth zone and due to compensatory growth, either within the leaf growth zone or between growing leaves. Under low N supply, F. rubra was the only species with the ability to develop a more branched root system and a greater length of tertiary roots than under high N. As a consequence, under low N supply F. rubra had a higher specific N uptake and a higher growth rate than the other species. This slow growing species also showed a higher nitrogen allocation to dead leaves and subsequently a higher potential N loss to leaf litter.

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Section: Discussionsupporting

confidence: 86%

Responses of plant traits of four grasses from contrasting habitats to defoliation and N supply

Gastal

Dawson

Thornton

2010

Nutr Cycl Agroecosyst

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“…However, when grown in competition with Centaurea maculosa, P. spicata exhibited facilitative effects from the presence of the neighbour, but total foliage was reduced by increasing clipping severity (Kennett et al 1992). At the end of our study, the effects of clipping were not apparent on the biomass production of P. spicata, except 1030 Carlyle, Cameron N. et al in the high water-high nutrient treatment, but it is likely that a more severe clipping treatment, created by either increasing the amount of biomass removed or subjecting the plant to multiple clippings, would have produced more significant reductions in plant biomass as has been observed in a field study with this grass (Arredondo & Johnson 1998). The resistance of F. campestris to clipping, in all but the high resource, competition-free case, is inconsistent with field experiments (Willms & Fraser 1992;Vujnovic et al 2000), but again our clipping regime on comparatively younger plants may not have been severe enough to induce a response.…”

Section: Interacting Effects On Biomassmentioning

confidence: 44%

Using three pairs of competitive indices to test for changes in plant competition under different resource and disturbance levels

Carlyle¹,

Fraser²,

Turkington³

2010

Journal of Vegetation Science

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Questions: How do different resource and disturbance levels interact to affect competition? How do different indices of competition change the interpretation of how competition changes under different resource and disturbance conditions? Location: Greenhouse, Thompson Rivers University, Kamloops, British Columbia, Canada. Methods: Three pairs of indices that have been used to differentiate the predictions of Grime (CSR) and Tilman's (R Ã ) theories were used to assess competition on two species of temperate bunchgrass, (Pseudorogeneria spicata and Festuca campestris) grown in a greenhouse on stress and disturbance gradients. Stress was created by manipulating the amount of water (high, low) and concentration of nutrient solution (high, low) added to pots, while disturbance was created by clipping (clipped, unclipped) in a fully factorial design. Plants were grown individually or with a single neighbour. The three pairs of indices were: (1) absolute and relative competition; (2) competitive effect and response; and, (3) competitive importance and intensity. Results: Absolute competition and competitive importance were the only indices responsive to the resource gradient, which supports CSR theory, and also the only ones to record an effect of disturbance on the strength of competition -under high resource conditions. The other indices showed few responses along the gradients, which supports R Ã theory. Measures of competitive effect and response did not differentiate the two theories. Conclusion: We show that some indices of competition show a decline with increased stress and disturbance, while other indices do not. Therefore, it is necessary to choose a competition index appropriate to the question being asked. Competitive importance and absolute competition were responsive to changes in stress and disturbance, while the other indices were not.Keywords: Absolute and relative competition; Clipping; Competitive effect and response; CSR strategy theory; Drought; Festuca campestris; Importance and intensity of competition; Nutrient availability; Pseudoroegneria spicata; R Ã theory. Nomenclature: Douglas et al. (1994).Abbreviations: C ab 5 absolute competition; C int 5 competitive intensity; C imp 5 competitive importance; C e 5 competitive effect; C r 5 competitive response.

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“…Root plasticity in response to environmental heterogeneity varies within and among taxonomic groups, and responses vary depending on root traits. For example, perennial grasses display less plasticity in root architecture than herbaceous dicots (Fitter & Strickland 1991; Taub & Goldberg 1996; Arredondo & Johnson 1998; Bouma et al . 2001a), and instead show plasticity for traits associated with size and photosynthate investment, such as root biomass, specific root length (SRL) and root diameter (Robinson & Rorison 1988; Hetrick et al .…”

Section: Introductionmentioning

confidence: 99%

“…Thus root phenotypic plasticity is expected in terrestrial grasses with an evolutionary history of frequent defoliation and temporal or spatial heterogeneity in the soil. Such morphological responses are known for temperate species (Eissenstat & Caldwell 1988; Arredondo & Johnson 1998; Arredondo & Johnson 1999) and for leaf traits in tropical grasses (McNaughton 1984). In contrast, the effects of defoliation on root traits are relatively unknown for the tropical savanna grasses; this is surprising given that tropical savanna grasses have perhaps the longest known history of herbivory of all extant plants (Stebbins 1981; Coughenour 1985).…”

Section: Introductionmentioning

confidence: 99%

Bimodal root diameter distributions in Serengeti grasses exhibit plasticity in response to defoliation and soil texture: implications for nitrogen uptake

Anderson¹,

Starmer

Thorne

2006

Functional Ecology

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Summary1. The effects of soil texture (low or high sand) and defoliation (clipped or unclipped) on root diameter distributions and nitrogen uptake were studied in the Serengeti grasses Digitaria macroblephara (Hack.) Stapf and Themeda triandra Forssk. in glasshouse cultures. 2. At the end of the experiment, plants were harvested and images of the washed roots were digitized using a scanner. Root size distributions were distinctly bimodal and were described with pairs of lognormal distributions with six parameters used as variables in subsequent analyses. To investigate N uptake, a nitrate solution containing 15 N was added to the soil 5 days before final harvest. 3. In both grasses, root diameter distributions were more responsive to defoliation than to soil texture. However, the two species diverged strongly in their investment in fine roots in the more sandy soils. 4. For each species, linear relationships were found among root biomass, root surface area and specific root length, which suggests that variation in root architecture is genetically constrained in each species. Plasticity emerged because the soil texture and defoliation experienced by an individual determined the specific architecture that it expressed within these linear relationships. 5. Root parameters obtained from the experiment and previously published root biomass and enzyme activities were used to predict 15 N uptake of the two grasses. Root diameter distribution and enzyme activities were important predictors of N uptake in the fast-growing grazing tolerant D. macroblephara , whereas root system size and root diameter distribution predicted N uptake in the slower growing, taller-statured T. triandra . 6. The differential responses of these grasses to variation in soils and defoliation are consistent with the hypothesis that habitat heterogeneity and herbivory interact to influence species coexistence in plant communities of African savannas.

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Clipping Effects on Root Architecture and Morphology of 3 Range Grasses

Cited by 23 publications

References 37 publications

Responses of plant traits of four grasses from contrasting habitats to defoliation and N supply

Responses of plant traits of four grasses from contrasting habitats to defoliation and N supply

Using three pairs of competitive indices to test for changes in plant competition under different resource and disturbance levels

Bimodal root diameter distributions in Serengeti grasses exhibit plasticity in response to defoliation and soil texture: implications for nitrogen uptake

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