+ Site Statistics
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Translate
+ Recently Requested

Coping with herbivory: Photosynthetic capacity and resource allocation in two semiarid Agropyron bunchgrasses

Coping with herbivory: Photosynthetic capacity and resource allocation in two semiarid Agropyron bunchgrasses

Oecologia 50(1): 14-24

Agropyron desertorum, a grazing-tolerant bunchgrass introduced to the western U.S. from Eurasia, and Agropyron spicatum, a grazing-sensitive bunchgrass native to North America, were examined in the field for photosynthetic capacity, growth, resource allocation, and tiller dynamics. These observations allowed identification of physiological characteristics that may contribute to grazing tolerance in semiarid environments. A uniform matrix of sagebrush, Artemisia tridentata, provided an ecologically relevant competitive environment for both bunch-grass species. Physiological activity, growth, and allocation were also followed during recovery from a severe defoliation treatment and were correlated with tiller dynamics.Potential photosynthetic carbon uptake of both species was dominated by stems and leaf sheaths during June, when maximum uptake rates occurred. For both species, water use efficiency of stems and sheaths was similar to that of leaf blades, but nitrogen investment per photosynthetic surface area was less than in blades. In addition, soluble carbohydrates in stems and sheaths of both species constituted the major labile carbon pools in control plants. Contrary to current theory, these findings suggest that culms from which leaf blades have been removed should be of considerable value to defoliated bunchgrasses, and in the case of partial defoliation could provide important supplies of organic nutrients for regrowth. These interpretations, based on total pool sizes, differ markedly from previous interpretations based on carbohydrate concentrations alone, which suggested that crowns contain large carbohydrate reserves. In this study, crowns of both species contained a minor component of the total plant carbohydrate pool.Following defoliation, A. desertorum plants rapidly reestablished a canopy with 3 to 5 times the photosynthetic surface of A. spicatum plants. This difference was primarily due to the greater number of quickly growing new tillers produced following defoliation. Agropyron spicatum produced few new tillers following defoliation despite adequate moisture, and carbohydrate pools that were equivalent to those in A. desertorum.Leaf blades of regrowing tillers had higher photosynthetic capacity than blades on unclipped plants of both species, but the relative increase, considered on a unit mass, area, or nitrogen basis, was greater for A. desertorum than for A. spicatum. Agropyron desertorum also had lower investment of nitrogen and biomass per unit area of photosynthetic tissues, more tillers and leaves per bunch, and shorter lived stems, all of which can contribute to greater tolerance of partial defoliation.Greater flexibility of resource allocation following defoliation was demonstrated by A. desertorum for both nitrogen and carbohydrates. Relatively more allocation to the shoot system and curtailed root growth in A. desertorum resulted in more rapid approach to the preclipping balance between the root and shoot systems, whereas root growth in A. spicatum continued unabated following defoliation. Nitrogen required for regrowth in both species was apparently supplied by uptake rather than reserve depletion. Carbohydrate pools in the shoot system of both species remained very low following severe defoliation and were approximately equivalent to carbon fixed in one day by photosynthesis of the whole canopy.

(PDF emailed within 0-6 h: $19.90)

Accession: 059551251

Download citation: RISBibTeXText

PMID: 28310058

DOI: 10.1007/BF00378790

Related references

Coping with herbivory photosynthetic capacity and resource allocation in 2 semi arid agropyron bunch grasses. Oecologia (Berlin) 50(1): 14-24, 1981

Resource allocation in strawberry implications for tolerance to herbivory. Bulletin of the Ecological Society of America 73(2 SUPPL): 354-355, 1992

Resource allocation in response to herbivory and gall formation in Linaria vulgaris. Plant Physiology and Biochemistry 135: 224-232, 2019

Herbivory alters resource allocation and compensation in the invasive tree Melaleuca quinquenervia. Ecological Entomology e; 30(3): 316-326, 2005

Effects of generalist herbivory on resistance and resource allocation by the invasive plant, Phytolacca americana. Insect Science 23(2): 191-199, 2016

Plant gas exchange of two bunchgrasses in relation to herbivory tolerance. Dissertation Abstracts International, B Sciences and Engineering 45(9): 2796B-2797B, 1985

Occam's razor cuts both ways: endophytes, resource allocation, herbivory, and mutualism: a reply to Rudgers et al. American Naturalist 176(1): 104-110, 2010

Intersexual differences in resource allocation, growth, and herbivory in dioecious palms species of genus Chamaedorea. Ecological Society of America Annual Meeting Abstracts 87: 330, 2002

Resource allocation patterns in a forb and a sedge in two arctic environments - short-term response to herbivory. Nordic Journal of Botany 22(6): 741-747, 2004

Relationship between reproductive resource allocation and resource capacity in the matriphagous spider, Chiracanthium japonicum (Araneae: Clubionidae). Journal of Ethology 21(1): 1-7, 2003

Phenology and culm-weight variation between two wheatgrass species: Agropyron smithii and Agropyron spicatum Semiarid rangelands, in Wyoming. Proceedings of the XVI International Grassland Congress: held at Lexington Kentucky USA June 15-24-1981 edited by J Allan Smith and Virgil W Hays: 426, 1983

Geographic patterns of herbivory and resource allocation to defense, growth, and reproduction in an invasive biennial, Alliaria petiolata. Oecologia 148(3): 384-395, 2006

Resource allocation in Copaifera langsdorffii (Fabaceae): how supra-annual fruiting affects plant traits and herbivory?. Revista de Biologia Tropical 64(2): 507-520, 2018

Compensation for herbivory by Cucumis sativus through increased photosynthetic capacity and efficiency. Oecologia 134(2): 167-175, 2003

Resource availability allocation to defense and tolerance to herbivory by tropical woody plant species differing in growth tactics. Association For Tropical Biology Annual Meeting Of The Association For Tropical Biology Held at The Aibs (American Institute Of Biological Sciences) Annual Meeting Of Scientific Societies; San Antonio, Texas, Usa, August 4-8, No Pagination Association For Tropical Biology: St Louis, Missouri, Usa Paper, 1991