Herbivory and the Mechanics of Fracture in Plants

Wright, Wendy; Vincent, Julian F. V.

doi:10.1111/j.1469-185x.1996.tb01280.x

Cited by 84 publications

(67 citation statements)

References 42 publications

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“…In linking the disciplines of plant mechanics with foraging behaviour we define five plant-based terms: (i) fracture force in tension, which is a measure of herbage strength and is estimated from the maximum force that produces fracture of the plant organ/s [80]; (ii) tensile strength, which is the fracture force in tension per unit cross-sectional area of the plant specimen [80,81]; (iii) maximum force in shear, also a measure of herbage strength and is the maximum force required to fracture the plant organ/s, and is determined from the height of the highest peak on the force displacement curve (N.B. : it does not represent the force to fracture the whole plant organ) [80]; (iv) specific work to fracture, equally known as toughness as it is measured by the energy required to shear the test specimen per unit cross-sectional area of the plant specimen [18,80] and (v) resistance, which is the theoretical, accumulated force required for severing all of the plant organs encompassed within a bite.…”

Section: Sward Structure and Biting Force Terminologymentioning

confidence: 99%

“…Wright and Vincent [81], in their review of the mechanics of fracture in plants, discussed the three modes of crack propagation in a leaf; shear, tension and torsion, and it is the modes of shear and tension that have attracted interest from plant and animal scientists alike. Assessment of the mechanical properties of grass leaves is far from new.…”

Section: Grass Leaf Anatomymentioning

confidence: 99%

“…Fracture force in tension is well correlated with the volume-fraction of sclerenchyma tissue [80] when the sclerenchyma tissue is below 15% of the volume-fraction of the leaf, and the fibres are laterally separated [71,73]. Above 15%, the fibres can be continuous across the leaf, rendering the leaf brittle [81], and thus more susceptible to fracture since the leaf will lose a large proportion of its strength with only a very small applied force [72]. The plant properties that increase mechanical resistance, chiefly the fibre component, are essentially the same as those that reduce plant digestibility [66,80].…”

Section: Grass Leaf Anatomymentioning

confidence: 99%

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Sward structural resistance and biting effort in grazing ruminants

Griffiths¹,

Gordon²

2003

Anim. Res.

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-Grazing ruminants face complex decisions in searching for and harvesting adequate forage to meet their requirements in the face of heterogeneity in the abundance, nutritive value and distribution of resources. Some of the major decisions which affect the bite mass and therefore, forage intake adjustments in bite depth, bite area and exerted bite force, are made in relation to heterogeneity in sward structure. A number of relationships have been established linking the adjustment of bite mechanics in response to variations in sward height and bulk density on temperate forages for animals of a range of body sizes. However, there is less consistency in the response of the bite mechanics to the greater variations in structural resistance that arise from the vertical and horizontal arrangements of the plant morphological organs of leaf, pseudostem and stem. Furthermore, only limited progress has been made in quantifying the biting forces involved in grazing, the linkages between the plant morphological organs and their effect on bite force and, the interaction with body mass. In this paper, we discuss the different hypotheses that have been proposed to explain the regulation of bite depth and provide evidence for their acceptance or rejection. We comment on the knowledge gap in understanding biting force mechanisms across animal species of contrasting body mass, and stress the need for differentiation between the concepts of biting force and biting effort.bite / effort / force / ruminants / structure Résumé -Résistance de structure du couvert végétal et effort de prélèvement des bouchées chez les ruminants au pâturage. Face à l'hétérogénéité de la ressource en abondance, en valeur nutritive et en répartition, les ruminants au pâturage doivent prendre des décisions complexes pour rechercher et récolter les fourrages nécessaires à leurs besoins. Certaines de ces décisions affectent la masse de la bouchée et donc, l'ajustement de l'ingestion en terme de profondeur et de surface de la bouchée, ainsi que de force de prélèvement. Ces décisions sont prises en relation avec l'hétérogénéité de la structure du couvert végétal. Nombre de relations ont été mises en évidence liant l'adaptation de la mécanique de la bouchée aux variations de la hauteur et de la densité du couvert végétal de fourrages tempérés pour des animaux de différentes tailles corporelles. En revanche, les grandes variations de résistance des végétaux, qui résultent des arrangements verticaux et horizontaux des organes morphologiques de la plante (feuille, gaine et tige), ont des effets variables sur la mécanique de la bouchée. De plus, seuls des progrès limités ont été accomplis pour quantifier les forces de prélève-ment des bouchées impliquées au pâturage, les liens entre les organes morphologiques de la plante et leurs effets sur les forces de prélèvement, ainsi que l'interaction avec le format des animaux. Dans cet article, nous discutons les différentes hypothèses qui ont été proposées pour expliquer la régulation de la profondeur des bouchées,...

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Section: Sward Structure and Biting Force Terminologymentioning

confidence: 99%

Section: Grass Leaf Anatomymentioning

confidence: 99%

Section: Grass Leaf Anatomymentioning

confidence: 99%

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Sward structural resistance and biting effort in grazing ruminants

Griffiths¹,

Gordon²

2003

Anim. Res.

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“…As arthropod damage expressed in plant fossils can be difficult to differentiate from abiotic trauma, we used the criteria outlined by Labandeira (2006, and the references therein) to identify arthropod-generated damage and also to distinguish herbivory from saprotrophy. Most importantly, herbivory damage is typically expressed by stereotypical feeding patterns consistent with modern analogues, the development of reaction tissue around the wound, development of necrotic flaps or veinal stringers around damaged tissue, and distinctive and consistent phytotissue-herbivore linkages that are incompatible with other forms of biological or physical trauma, such as that caused by fungi (Parbery, 1996;Taylor and Osborn, 1996) or abiotic processes (Wilson, 1984;Michels et al, 1995;Wright and Vincent, 1996;Racskó et al, 2010). We sought to assign examples of plant damage to the principal functional feeding groups outlined by Labandeira et al (2007a): viz., external foliage feeding (here subdivided into the categories of leaf-margin feeding, apical feeding, surface feeding and hole feeding), piercing-and-sucking, boring, leaf mining, galling, seed feeding, palynophagy, nectarivory and oviposition.…”

Section: Methodsmentioning

confidence: 99%

The record of Australian Jurassic plant–arthropod interactions

McLoughlin

Martin

Beattie³

2015

Gondwana Research

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A survey of Australian Jurassic plant fossil assemblages reveals examples of foliar and wood damage generated by terrestrial arthropods attributed to leaf-margin feeding, surface feeding, lamina hole feeding, galling, piercingand-sucking, leaf-mining, boring and oviposition. These types of damage are spread across a wide range of fern and gymnosperm taxa, but are particularly well represented on derived gymnosperm clades, such as Pentoxylales and Bennettitales. Several Australian Jurassic plants show morphological adaptations in the form of minute marginal and apical spines on leaves and bracts, and scales on rachises that likely represent physical defences against arthropod herbivory. Only two entomofaunal assemblages are presently known from the Australian Jurassic but these reveal a moderate range of taxa, particularly among the Orthoptera, Coleoptera, Hemiptera and Odonata, all of which are candidates for the dominant feeding traits evidenced by the fossil leaf and axis damage. The survey reveals that plant-arthropod interactions in the Jurassic at middle to high southern latitudes of southeastern Gondwana incorporated a similar diversity of feeding strategies to those represented in coeval communities from other provinces. Further, the range of arthropod damage types is similar between Late Triassic and Jurassic assemblages from Gondwana despite substantial differences in the major plant taxa, implying that terrestrial invertebrate herbivores were able to successfully transfer to alternative plant hosts during the floristic turnovers at the Triassic-Jurassic transition.

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“…Tough leaves could be avoided by herbivores because of higher energetic expenses for harvesting, but also because of a lower palatability (Wright and Vincent 1996). Naturally this information is of use to the plant breeder who can select for important characteristics (Vincent 1982).…”

Section: Physical Characteristicsmentioning

confidence: 99%

Cultivar Effects of Perennial Ryegrass on Herbage Intake by Grazing Dairy Cows

Smit¹

Fresh Herbage for Dairy Cattle

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Abstract. Perennial ryegrass is the most abundant grass species in temperate climates. An increased herbage intake of dairy cows by breeding new cultivars could have a large potential impact on agriculture. The effects of cultivars on sward structure, nutritive value, physical characteristics and disease resistance of perennial ryegrass are discussed. Cultivar differences were found in several studies for plant factors such as dry-matter yield, green-leaf mass and bulk density. Clear cultivar differences in nutritive value of perennial ryegrass were observed, especially the cultivar rankings for concentrations of water-soluble carbohydrates and acid detergent lignin were found to be consistent during the season and across years. Cultivar effects were also found for physical characteristics, e.g., tensile strength and resistance against crown rust (Puccinia coronata f. sp. lolii). The different plant-related cultivar effects were evaluated for their effects on herbage intake by grazing dairy cows. Differences among cultivars for the concentration of water-soluble carbohydrates affected the preference behaviour of dairy cattle. The possibilities to enhance dry-matter intake in a grazing situation through breeding can mainly be achieved by selecting for a better crown-rust resistance and a higher dry-matter production. A higher dry-matter production would give more opportunities for selection by dairy cows and might, therefore, enhance herbage intake at the animal level, but the production of more herbage would certainly enhance herbage intake at farm level.

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Herbivory and the Mechanics of Fracture in Plants

Cited by 84 publications

References 42 publications

Sward structural resistance and biting effort in grazing ruminants

Sward structural resistance and biting effort in grazing ruminants

The record of Australian Jurassic plant–arthropod interactions

Cultivar Effects of Perennial Ryegrass on Herbage Intake by Grazing Dairy Cows

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