Biomass Partitioning Following Defoliation of Annual and Perennial Mediterranean Grasses

Gutman, Mario; Noy‐Meir, Imanuel; Pluda, Daniel C.; Seligman, N. G.; Rothman, Steven M.; Sternberg, Marcelo

doi:10.5751/es-00308-050201

Cited by 16 publications

(19 citation statements)

References 36 publications

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“…However, the observed increase in proportional abundance of exotic grasses suggests that they received an additional benefit relative to annual forbs, perhaps because grazed annual grasses produced more tillers per individual prior to flowering. This mechanism has been documented in annual grasses with other grazers (Gutman et al 2002;NoyMeir and Briske 1996) and under mowing (Lush 1988), and may be a direct response to leaf injury or an indirect response to light availability. Van der Graaf et al (2005) also showed an increased production of branches in the perennial grass Festuca rubra under grazing by Barnacle geese (Branta leucopsis).…”

Section: Grasses Under Grazingmentioning

confidence: 95%

Exotic herbivores directly facilitate the exotic grasses they graze: mechanisms for an unexpected positive feedback between invaders

Best

Arcese

2008

Oecologia

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The ability of an exotic species to establish in a system may depend not only on the invasibility of the native community, but also on its interactions with other exotic species. Though examples of mutually beneficial interactions between exotic species are known, few studies have quantified these effects or identified specific mechanisms. We used the co-invasion of an endangered island ecosystem by exotic Canada geese (Branta canadensis) and nine exotic annual grasses to study the effects of an invading herbivore on the success of invading grasses. On our study islands in southwestern Canada, we found that geese fed selectively on the exotic grasses and avoided native forbs. Counter to current theory suggesting that the grasses should be limited by a selective enemy, however, the grasses increased in proportional abundance under grazing whereas forbs showed declining abundance. Testing potential mechanisms for the effects of grazing on grasses, we found that the grasses produced more stems per area when grazing reduced vegetation height and prevented litter accumulation. Forming dense mats of short stems appeared to be an efficient reproductive and competitive strategy that the Eurasian grasses have evolved in the presence of grazers, conferring a competitive advantage in a system where the native species pool has very few annual grasses and no grazers. Germination trials further demonstrated that selective herbivory by geese enables their dispersal of exotic grass seed between heavily invaded feeding areas and the small islands used for nesting. In summary, the exotic geese facilitated both the local increase and the spatial spread of exotic grasses, which in turn provided the majority of their diet. This unexpected case of positive feedback between exotic species suggests that invasion success may depend on the overall differences between the evolutionary histories of the invaders and the evolutionary history of the native community they enter.

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Section: Grasses Under Grazingmentioning

confidence: 95%

Exotic herbivores directly facilitate the exotic grasses they graze: mechanisms for an unexpected positive feedback between invaders

Best

Arcese

2008

Oecologia

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“…Therefore, the flowering was delayed and seed formation was also delayed leading to a reduced seed yield in clipped plants in two Indigofera spp. Moreover, the shoot clipping treatments invariably cause a reduction in the amount of biomass partitioned to the reproductive organs, and affects flowering (Gutman et al, 2001). Leaf clipping at flower initiation stage induces the capacity to compensate source loss through the re-growth of leaves in soybean (Board and Harville, 1998;Borras et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Floral morphology and seed yield in two Indigofera spp. as affected by shoot clipping

Jahan

Sarwar

Fakir

2014

J Bangladesh Agric Univ

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An experiment was carried out to know the effect of shoot clipping on floral morphology and seed yield in two Indigofera spp. viz. I. tinctoria L. and I. suffruticosa Mill. All parts of shoot including the main stem were clipped at 60 cm height from the base at 120 days after sowing (DAS). At 120 DAS, I. tinctoria already exhibited 1 st flowering while I. suffruticosa showed no flowering. Shoot clipping had significant effect on almost all floral morphological features in two Indigofera spp. Flower raceme −1 and pod raceme −1 were fewer in clipped plant than in unclipped one. Shoot clipping altered the size of different floral parts to a great extent. The seed yield was decreased in clipped plant than that of unclipped one. Shoot clipping decreased flower and pod size and seed yield in two Indigofera spp.

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“…Tillering in grasses is a very dynamic process and time of sampling can strongly influence the situation encountered (Gutman et al. , 2001).…”

Section: Morphological Traits Related To Persistence and Vigourmentioning

confidence: 99%

“…Nutrition dynamics must be studied in this context. The cost in reduced resource storage may have consequences for subsequent population dynamics and yield (Gutman et al. , 2001).…”

Section: Morphological Traits Related To Persistence and Vigourmentioning

confidence: 99%

Infrequent and intense defoliation benefits dry‐matter accumulation and persistence of clipped Arrhenatherum elatius

D’Angelo

Postulka

Ferrari

2005

Grass and Forage Science

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The objective was to determine how the frequency and intensity of defoliation of tall oat grass [Arrhenatherum elatius (L.) Presl.], affected (i) annual dry-matter (DM) accumulation, (ii) seasonal distribution of the accumulated forage, and (iii) morphological traits related to persistence and vigour. Data were collected twice a year throughout three growing years, beginning the second year after establishment. Two frequencies (A: each time modal height of plants reached 20 cm; B: each time modal height of plants reached 40 cm) and two defoliation intensities (I: 5 cm; II: 10 cm stubble) were arranged in a completely randomized block design with a fully factorial combination and four replicates. Measurements were made of annual DM accumulation, seasonal distribution of accumulated DM and morphological traits related to persistence and vigour, i.e. number of tillers m )2 , number of tussocks m )2 , crown diameter, and crown area of tussocks. The infrequent defoliation (B) increased annual DM accumulation besides maintaining levels of persistence and vigour. The most productive treatment (BI) had a significantly higher annual DM accumulation than treatments AI and AII. Frequent and severe defoliations (treatment AI) led to plant depletion, which reduced crown diameter, number of tillers m )2 and crown area at the end of the third year compared with infrequent but severe defoliation (treatment BI). Annual DM accumulation was intermediate for less intense defoliations (AII), which produced forage during winter, but resulted in less vigorous plants by the end of the experiment.Crown area was a good indicator of tiller number, particularly under frequent defoliation.

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Biomass Partitioning Following Defoliation of Annual and Perennial Mediterranean Grasses

Cited by 16 publications

References 36 publications

Exotic herbivores directly facilitate the exotic grasses they graze: mechanisms for an unexpected positive feedback between invaders

Exotic herbivores directly facilitate the exotic grasses they graze: mechanisms for an unexpected positive feedback between invaders

Floral morphology and seed yield in two Indigofera spp. as affected by shoot clipping

Infrequent and intense defoliation benefits dry‐matter accumulation and persistence of clipped Arrhenatherum elatius

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