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John P. Bryant

Bio: John P. Bryant is an academic researcher from University of Alaska Fairbanks. The author has contributed to research in topics: Herbivore & Snowshoe hare. The author has an hindex of 46, co-authored 84 publications receiving 12658 citations.


Papers
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Journal ArticleDOI
22 Nov 1985-Science
TL;DR: Resource availability in the environment is proposed as the major determinant of both the amount and type of plant defense, and theories on the evolution of plant defenses are compared with other theories.
Abstract: The degree of herbivory and the effectiveness of defense varies widely among plant species. Resource availability in the environment is proposed as the major determinant of both the amount and type of plant defense. When resource are limited, plants with inherently slow growth are favored over those with fast growth rates; slow rates in turn favor large investments in antiherbivore defenses. Leaf lifetime, also determined by resource availability, affects the relative advantages of defenses with different turnover rates. Relative limitation of different resources also constrains the types of defenses. The proposals are compared with other theories on the evolution of plant defenses.

3,601 citations

Journal ArticleDOI
01 May 1983-Oikos
TL;DR: Fundamental differences between the response of woody plants and graminoids to vertebrate herbivory suggest that the dynamics of browsing systems and grazing systems are qualitatively different.
Abstract: The evolutionary response of plants to herbivory is constrained by the availability of resources in the environment. Woody plants adapted to low-resource environments have intrinsically slow growth rates that limit their capacity to grow rapidly beyond the reach of most browsing mammals. Their low capacity to acquire resources limits their potential for compensatory growth which would otherwise enable them to replace tissue destroyed by browsing. Plants adapted to low-resource environments have responded to browsing by evolving strong constitutive defenses with relatively low ontogenetic plasticity. Because nutrients are often more limiting than light in boreal forests, slowly growing boreal forest trees utilize carbon-based rather than nitrogen-based defenses. More rapidly growing shade-intolerant trees that are adapted to growth in high-resource environments are selected for competitive ability and can grow rapidly beyond the range of most browsing mammals. Moreover, these plants have the carbon and nutrient reserves necessary to replace tissue lost to browsing through compensatory growth. However, because browsing of juvenile plants reduces vertical growth and thus competitive ability, these plants are selected for resistance to browsing during the juvenile growth phase. Consequently, early successional boreal forest trees have responded to browsing by evolving strong defenses during juvenility only. Because severe pruning causes woody plants to revert to a juvenile form, resistance of woody plants to hares increases after severe hare browsing as occurs during hare population outbreaks. This increase in browsing resistance may play a significant role in boreal forest plant-hare interactions. Unlike woody plants, graminoids retain large reserves of carbon and nutrients below ground in both low-resource and high-resource environments and can respond to severe grazing through compensatory growth. These fundamental differences between the response of woody plants and graminoids to vertebrate herbivory suggest that the dynamics of browsing systems and grazing systems are qualitatively different.

2,439 citations

01 Jan 1980
TL;DR: During winter do subarctic browsing vertebrates feed preferentially upon plant tissues that contain relatively high concentrations of proximal nutrients or energy, or consistently avoid plant specimens that contain low concentrations of these nutrients and energy?
Abstract: Plant palatability frequently moderates vertebrate herbivore forage selec­ tion patterns (e.g. 72, 73, 103, 104, 111, 137, 179,195). There is, however, considerable debate as to which plant chemical characteristics control pala­ tability (e.g. 9, 42, 110, 118, 120, 216). On the one hand, forage proximal nutritional quality is believed to be of primary importance (e.g. 18, 51, 103, 114, 130, 133, 137, 161, 173, 215). On the other, there is increasing specula­ tion that forage selection patterns are largely the result of avoidance of plant secondary constituents that are antagonistic to vertebrate herbivore fitness (e.g. 1, 2, 9, 12, 25, 49, 112, 116, 120, 141, 153, 165, 199,200). In this paper we examine these alternatives for a specific system. We consider the interface between subarctic browsing vertebrates and woody browse plants during winter and attempt to answer the following questions: During winter do subarctic browsing vertebrates (a) feed prefer­ entially upon plant tissues that contain relatively high concentrations of proximal nutrients or energy, or (b) consistently avoid plant tissues that

452 citations

Journal ArticleDOI
TL;DR: In this article, the authors examine the interface between subarctic browsing vertebrates and woody browse plants during winter and attempt to answer the following questions: during winter do sub-arctic browse vertebrates (a) feed preferentially upon plant tissues that contain relatively high concentrations of proximal nutrients or energy, or (b) consistently avoid plant proteins that are antagonistic to vertebrate herbivore fitness.
Abstract: Plant palatability frequently moderates vertebrate herbivore forage selection patterns (e.g. 72, 73, 103, 104, 111, 137, 179, 195). There is, however, considerable debate as to which plant chemical characteristics control palatability (e.g. 9, 42, 110, 118, 120, 216). On the one hand, forage proximal nutritional quality is believed to be of primary importance (e.g. 18, 51, 103, 114, 130, 133, 137, 161, 173, 215). On the other, there is increasing speculation that forage selection patterns are largely the result of avoidance of plant secondary constituents that are antagonistic to vertebrate herbivore fitness (e.g. 1, 2, 9, 12, 25, 49, 112, 116, 120, 141, 153, 165, 199, 200). In this paper we examine these alternatives for a specific system. We consider the interface between subarctic browsing vertebrates and woody browse plants during winter and attempt to answer the following questions: During winter do subarctic browsing vertebrates (a) feed preferentially upon plant tissues that contain relatively high concentrations of proximal nutrients or energy, or (b) consistently avoid plant tissues that

440 citations

Journal ArticleDOI
TL;DR: Mammals must overcome several challenges to exploit woody plants; these include variation among plant species, individuals, growth stages, and parts in their nutritional value and mechanical and chemical defenses.
Abstract: Mammals must overcome several challenges to exploit woody plants; these include variation among plant species, individuals, growth stages, and parts in their nutritional value and mechanical and chemical defenses (91). The latter are especially significant because woody plants produce a variety of secondary metabolites (56), many of which are chemical defenses against browsing by mammals and some of which appear to be an evolutionary 431 0066-4162/91/1120-043 1$02.00

382 citations


Cited by
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Journal Article
TL;DR: This book by a teacher of statistics (as well as a consultant for "experimenters") is a comprehensive study of the philosophical background for the statistical design of experiment.
Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

13,333 citations

Journal ArticleDOI
TL;DR: A conceptual model of the evolution of plant defense is concluded, in which plant physioligical trade-offs interact with the abiotic environment, competition and herbivory.
Abstract: Physiological and ecological constraints play key roles in the evolution of plant growth patterns, especially in relation to defenses against herbivores. Phenotypic and life history theories are unified within the growth-differentiation balance (GDB) framework, forming an integrated system of theories explaining and predicting patterns of plant defense and competitive interactions in ecological and evolutionary time. Plant activity at the cellular level can be classified as growth (cell division and enlargement) of differentiation (chemical and morphological changes leading to cell maturation and specialization). The GDB hypothesis of plant defense is premised upon a physiological trade-off between growth and differentiation processes. The trade-off between growth and defense exists because secondary metabolism and structural reinforcement are physiologically constrained in dividing and enlarging cells, and because they divert resources from the production of new leaf area. Hence the dilemma of plants: Th...

3,843 citations

Journal ArticleDOI
22 Nov 1985-Science
TL;DR: Resource availability in the environment is proposed as the major determinant of both the amount and type of plant defense, and theories on the evolution of plant defenses are compared with other theories.
Abstract: The degree of herbivory and the effectiveness of defense varies widely among plant species. Resource availability in the environment is proposed as the major determinant of both the amount and type of plant defense. When resource are limited, plants with inherently slow growth are favored over those with fast growth rates; slow rates in turn favor large investments in antiherbivore defenses. Leaf lifetime, also determined by resource availability, affects the relative advantages of defenses with different turnover rates. Relative limitation of different resources also constrains the types of defenses. The proposals are compared with other theories on the evolution of plant defenses.

3,601 citations

Book
01 Sep 2011
TL;DR: In this paper, the Ecosystem Concept is used to describe the Earth's Climate System and Geology and Soils, and the ecosystem concept is used for managing and sustaining ecosystems.
Abstract: I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References

3,086 citations

Journal ArticleDOI
TL;DR: In this article, the authors propose case studies on various topics to identify management practices, technologies and policies that promote the positive and mitigate the negative impacts of agriculture on biodiversity, and enhance productivity and the capacity to sustain livelihoods.
Abstract: Background The programme of work on agricultural biodiversity, adopted by the Conference of Parties in decision V/5, makes provision for case studies on various topics to identify management practices, technologies and policies that promote the positive and mitigate the negative impacts of agriculture on biodiversity, and enhance productivity and the capacity to sustain livelihoods. More specifically, activity 2.1 of the Programme of Work calls for a series of case studies, in a range of environments and production systems, and in each region: (a) To identify key goods and services provided by agricultural biodiversity, needs for the conservation and sustainable use of components of this biological diversity in agricultural ecosystems, and threats to such diversity;

2,990 citations