Journal ArticleDOI
Defoliation responses of western wheatgrass populations with diverse histories of prairie dog grazing.
James K. Detling,E. L. Painter +1 more
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Photosynthesis and regrowth were compared over a 10-day period following defoliation of about 75% of the tillers of western wheatgrass plants collected from a black-tailed prairie dog town and a grazing exclosure at Wind Cave National Park, South Dakota, and rates did not differ between plants of the two populations.Abstract:
Photosynthesis and regrowth were compared over a 10-day period following defoliation of about 75% of the tillers of western wheatgrass (Agropyron smithii) plants collected from a black-tailed prairie dog (Cynomys ludovicianus) town and a grazing exclosure at Wind Cave National Park, South Dakota. Prior to defoliation, dog town plants had more tillers, but fewer leaves per tiller, shorter and narrower leaf blades, more horizontal leaves, and higher leaf blade/leaf sheath ratios than plants from the grazing exclosure. Rates of net photosynthesis (PN) did not differ significantly among plants of the two populations, either prior to or following defoliation. From Days 2–10 following defoliation, PN of remaining undamaged leaves averaged 104% of predefoliation rates while PN of similar leaves on non-defoliated plants declined steadily with time. averaging only 79% predefoliation rates during this period. Following defoliation, transpiration rates followed similar trends to CO2 exchange, and rates did not differ between plants of the two populations. Absolute rates of leaf elongation and shoot production were greater in plants from the exclosure. However, defoliation of plants from the exclosure population resulted in a 20% reduction in their cumulative shoot dry weight, while cumulative shoot dry weight of plants from the prairie dog town was not significantly affected by defoliation. This apparent ability of plants from the prairie dog town population to withstand defoliation better than plants from the exclosure was atributed to factors such as the higher leaf blade/leaf sheath ratio and more horizontal leaf angles of plants from the former population.read more
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References
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Journal ArticleDOI
Grazing as an Optimization Process: Grass-Ungulate Relationships in the Serengeti
TL;DR: Experiments in Tanzania's Serengeti National Park showed that net above-ground primary productivity of grasslands was strongly regulated by grazing intensity in wet-season concentration areas of the large ungulate fauna, suggesting that conventional definitions of overgrazing may be inapplicable to these native plant-herbivore systems.
Journal ArticleDOI
Comparison of Conventional and Automated Procedures for Nitrogen, Phosphorus, and Potassium Analysis of Plant Material Using a Single Digestion1
Photosynthesis of crop plants as influenced by light, carbon dioxide, temperature, and stomatal diffusion resistance
TL;DR: In this article, the effect of light intensity, leaf temperature, and C0 2 concentration on photosynthetic rate in leaves of crop plants was estimated in absolute units, which allowed quantitative comparison of micrometeorological and physiological effects on photosynthesis.
Journal ArticleDOI
The Carbon Balance of Plants
TL;DR: This analysis will stimulate studies which will provide, for a given series of bio types, the total information on carbon gain, use, and loss, so that quantitative models can be derived relating to shortand long-term environmental influences.
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Phytophagous Insects as Regulators of Forest Primary Production
TL;DR: Although outbreaks (either local or extensive) do reduce plant production temporarily, they commonly occur in individual plants or in whole forest systems that are not particularly productive-that is, those which are under stress resulting from inadequate or excessive moisture, nutrient deficiencies, or pollution, or are senescent, having already passed their peak efficiencies in biomass production.