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Author: Oscar J. Valverde-Barrantes
Publisher:
ISBN:
Category : Angiosperms
Languages : en
Pages : 223
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Book Description
Geoffrey Baylis formulated in 1975 that roots of the ancestral angiosperms were thick, scarcely-branched, and bearing large cortex areas, which was essential for plants that probably had limited capacity for direct nutrient absorption in terrestrial habitats. Over time plants evolved to produce finer roots, increased branch frequency, and developed root hairs, probably to improve nutrient scavenging and acquisition. Therefore, it was assumed that root architecture reflect the degree of dependency of flowering plants for AM fungal associations. Nonetheless, Baylis ideas were rarely tested empirically and there are still important gaps in the understanding of the process leading to the actual patterns in root morphology among angiosperms. Moreover the ecological implications of the mechanisms explaining root trait diversity have not been properly addressed. Throughout this dissertation I tried to expand our knowledge of root ecology by focusing on two important topics: 1) The exploration of the possible steps involved in the evolution of root traits during woody angiosperm evolution, and 2) the ecological implications that these adaptations may play in the belowground interactions of tree communities. The first topic was explored in chapters two and three. In chapter two, we provided compelling evidence that variation is in large measure due to alternative trait syndromes evolved independently among angiosperm lineages. Moreover, our findings indicated that morphology traits in roots were independent from leaf morphology, suggesting different selective factors affecting the evolutionary trends of both organs. In chapter three, I tested the idea that the described separation in root traits among phylogenetic angiosperm groups reflects their dependency from mycorrhizal associations. I extended this hypothesis, providing evidence that the observed root trait syndromes in woody angiosperms reflect different evolutionary pathways that includes the entire root system rather than only the root tips. The previously described trend in root diameter corresponds with decreases in cortical tissue, suggesting an strong selection for reduced habitat for mycorrhizal communities. I concluded that alternative morphologies may reflect different nutrient acquisition strategies possibly related to tradeoffs between direct nutrient acquisition and allocation to fungal partners. In chapters four and five, I explored the role that root trait diversity and species identity may play in the interactions of species belowground in a natural ecosystem. In chapter four, results showed that the interspecific variation in root morphological traits is not related to specific soil conditions. Rather, it seems to enhance the ability of species to coexist in relatively aggregated conditions. Accordingly, in chapter five, we found no evidence for spatial segregation among species. In fact, root biomass variation was explained by both resource availability and phylogenetic diversity, highlighting the importance that evolutionary process may have in ecosystem stability.
Author: Oscar J. Valverde-Barrantes
Publisher:
ISBN:
Category : Angiosperms
Languages : en
Pages : 223
Get Book Here
Book Description
Geoffrey Baylis formulated in 1975 that roots of the ancestral angiosperms were thick, scarcely-branched, and bearing large cortex areas, which was essential for plants that probably had limited capacity for direct nutrient absorption in terrestrial habitats. Over time plants evolved to produce finer roots, increased branch frequency, and developed root hairs, probably to improve nutrient scavenging and acquisition. Therefore, it was assumed that root architecture reflect the degree of dependency of flowering plants for AM fungal associations. Nonetheless, Baylis ideas were rarely tested empirically and there are still important gaps in the understanding of the process leading to the actual patterns in root morphology among angiosperms. Moreover the ecological implications of the mechanisms explaining root trait diversity have not been properly addressed. Throughout this dissertation I tried to expand our knowledge of root ecology by focusing on two important topics: 1) The exploration of the possible steps involved in the evolution of root traits during woody angiosperm evolution, and 2) the ecological implications that these adaptations may play in the belowground interactions of tree communities. The first topic was explored in chapters two and three. In chapter two, we provided compelling evidence that variation is in large measure due to alternative trait syndromes evolved independently among angiosperm lineages. Moreover, our findings indicated that morphology traits in roots were independent from leaf morphology, suggesting different selective factors affecting the evolutionary trends of both organs. In chapter three, I tested the idea that the described separation in root traits among phylogenetic angiosperm groups reflects their dependency from mycorrhizal associations. I extended this hypothesis, providing evidence that the observed root trait syndromes in woody angiosperms reflect different evolutionary pathways that includes the entire root system rather than only the root tips. The previously described trend in root diameter corresponds with decreases in cortical tissue, suggesting an strong selection for reduced habitat for mycorrhizal communities. I concluded that alternative morphologies may reflect different nutrient acquisition strategies possibly related to tradeoffs between direct nutrient acquisition and allocation to fungal partners. In chapters four and five, I explored the role that root trait diversity and species identity may play in the interactions of species belowground in a natural ecosystem. In chapter four, results showed that the interspecific variation in root morphological traits is not related to specific soil conditions. Rather, it seems to enhance the ability of species to coexist in relatively aggregated conditions. Accordingly, in chapter five, we found no evidence for spatial segregation among species. In fact, root biomass variation was explained by both resource availability and phylogenetic diversity, highlighting the importance that evolutionary process may have in ecosystem stability.
Author: Hans de Kroon
Publisher: Springer Science & Business Media
ISBN: 9783540001850
Category : Science
Languages : en
Pages : 424
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Book Description
In the course of evolution, a great variety of root systems have learned to overcome the many physical, biochemical and biological problems brought about by soil. This development has made them a fascinating object of scientific study. This volume gives an overview of how roots have adapted to the soil environment and which roles they play in the soil ecosystem. The text describes the form and function of roots, their temporal and spatial distribution, and their turnover rate in various ecosystems. Subsequently, a physiological background is provided for basic functions, such as carbon acquisition, water and solute movement, and for their responses to three major abiotic stresses, i.e. hard soil structure, drought and flooding. The volume concludes with the interactions of roots with other organisms of the complex soil ecosystem, including symbiosis, competition, and the function of roots as a food source.
Author: Iván Prieto
Publisher: Frontiers Media SA
ISBN: 2832517927
Category : Science
Languages : en
Pages : 169
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Book Description
Author: Grégoire T. Freschet
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Abstract: In the context of a recent massive increase in research on plant root functions and their impact on the environment, root ecologists currently face many important challenges to keep on generating cutting-edge, meaningful and integrated knowledge. Consideration of the below-ground components in plant and ecosystem studies has been consistently called for in recent decades, but methodology is disparate and sometimes inappropriate. This handbook, based on the collective effort of a large team of experts, will improve trait comparisons across studies and integration of information across databases by providing standardised methods and controlled vocabularies. It is meant to be used not only as starting point by students and scientists who desire working on below-ground ecosystems, but also by experts for consolidating and broadening their views on multiple aspects of root ecology. Beyond the classical compilation of measurement protocols, we have synthesised recommendations from the literature to provide key background knowledge useful for: (1) defining below-ground plant entities and giving keys for their meaningful dissection, classification and naming beyond the classical fine-root vs coarse-root approach; (2) considering the specificity of root research to produce sound laboratory and field data; (3) describing typical, but overlooked steps for studying roots (e.g. root handling, cleaning and storage); and (4) gathering metadata necessary for the interpretation of results and their reuse. Most importantly, all root traits have been introduced with some degree of ecological context that will be a foundation for understanding their ecological meaning, their typical use and uncertainties, and some methodological and conceptual perspectives for future research. Considering all of this, we urge readers not to solely extract protocol recommendations for trait measurements from this work, but to take a moment to read and reflect on the extensive information contained in this broader guide to root ecology, including sections I-VII and the many introductions to each section and root trait description. Finally, it is critical to understand that a major aim of this guide is to help break down barriers between the many subdisciplines of root ecology and ecophysiology, broaden researchers' views on the multiple aspects of root study and create favourable conditions for the inception of comprehensive experiments on the role of roots in plant and ecosystem functioning
Author: Jun J. Abe
Publisher: Springer Science & Business Media
ISBN: 9401729239
Category : Science
Languages : en
Pages : 444
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Book Description
The root is the organ that functions as the interface between the plant and the earth environment. Many human management practices involving crops, forests and natural vegetation also affect plant growth through the soil and roots. Understanding the morphology and function of roots from the cellular level to the level of the whole root system is required for both plant production and environmental protection. This book is at the forefront of plant root science (rhizology), catering to professional plant scientists and graduate students. It covers root development, stress physiology, ecology, and associations with microorganisms. The chapters are selected papers originally presented at the 6th Symposium of the International Society of Root Research, where plant biologists, ecologists, soil microbiologists, crop scientists, forestry scientists, and environmental scientists, among others, gathered to discuss current research results and to establish rhizology as a newly integrated research area.
Author: Hans de Kroon
Publisher: Springer Science & Business Media
ISBN: 3662097842
Category : Science
Languages : en
Pages : 409
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Book Description
In the course of evolution, a great variety of root systems have learned to overcome the many physical, biochemical and biological problems brought about by soil. This development has made them a fascinating object of scientific study. This volume gives an overview of how roots have adapted to the soil environment and which roles they play in the soil ecosystem. The text describes the form and function of roots, their temporal and spatial distribution, and their turnover rate in various ecosystems. Subsequently, a physiological background is provided for basic functions, such as carbon acquisition, water and solute movement, and for their responses to three major abiotic stresses, i.e. hard soil structure, drought and flooding. The volume concludes with the interactions of roots with other organisms of the complex soil ecosystem, including symbiosis, competition, and the function of roots as a food source.
Author: Eric Garnier
Publisher: Oxford University Press
ISBN: 0198757379
Category : Nature
Languages : en
Pages : 255
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Book Description
Biological diversity, the variety of living organisms on Earth, is traditionally viewed as the diversity of taxa, and species in particular. However, other facets of diversity also need to be considered for a comprehensive understanding of evolutionary and ecological processes. This novel book demonstrates the advantages of adopting a functional approach to diversity in order to improve our understanding of the functioning of ecological systems and theircomponents. The focus is on plants, which are major components of these systems, and for which the functional approach has led to major scientific advances over the last 20 years. PlantFunctional Diversity presents the rationale for a trait-based approach to functional diversity in the context of comparative plant ecology and agroecology. It demonstrates how this approach can be used to address a number of highly debated questions in plant ecology pertaining to plant responses to their environment, controls on plant community structure, ecosystem properties, and the services these deliver to human societies. This research level text will be of particular relevance and use tograduate students and professional researchers in plant ecology, agricultural sciences and conservation biology.
Author: Edward A. Johnson
Publisher: Cambridge University Press
ISBN: 1316785130
Category : Nature
Languages : en
Pages : 495
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Book Description
Biogeoscience is a rapidly growing interdisciplinary field that aims to bring together biological and geophysical processes. This book builds an enhanced understanding of ecosystems by focusing on the integrative connections between ecological processes and the geosphere, hydrosphere and atmosphere. Each chapter provides studies by researchers who have contributed to the biogeoscience synthesis, presenting the latest research on the relationships between ecological processes, such as conservation laws and heat and transport processes, and geophysical processes, such as hillslope, fluvial and aeolian geomorphology, and hydrology. Highlighting the value of biogeoscience as an approach to understand ecosystems, this is an ideal resource for researchers and students in both ecology and the physical sciences.
Author: Thomas Adams
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Despite fine roots accounting for up to 50% of global terrestrial net primary productivity and 60% of soil respiration, surprisingly little is known about their ecology. Much of our ignorance involving fine-root ecology stems from the difficulty in observing roots in situ without disturbing the environment they inhabit. As a result, the ecological study of roots is still in its infancy. Through the use of minirhizotrons and isotopic techniques, we are beginning to gain a better understanding of how long roots live. However based on the different methodological approaches employed, the answer to this seemingly basic question can differ by as much as five fold. Beyond these methodological discrepancies, a basic understanding of the controlling factors that govern root lifespan remains elusive. Marshall and Waring put forward one of the early hypotheses regarding the controls of fine-root lifespan. They hypothesized that fine roots are initially constructed with a static carbohydrate reserve and the use of this finite reserve to fuel the metabolic demands of the root dictates the root's longevity. In Chapter 2, we examine this hypothesis in greater depth by labeling Sassafras albidum trees with 99% 13CO2 and tracking the fate of the label in fine roots that were at least two weeks old at the time of labeling. If a root's carbohydrate reserves truly are determined at initiation, than no 13C labeled photosynthate should appear in the carbohydrate pools of existing, non-elongating roots. We found that both root non-structural and structural carbon pools incorporate carbon from current photosynthate and as a result we found no support for the underlying assumptions of hypothesis put forward by Marshall and Waring. In Chapter 3, we investigate another hypothesis concerning the control of fine-root lifespan, namely that root lifespan is dictated by some metric of the costs of building and maintaining the root compared to the benefits the root supplies in terms of nutrient or water acquisition. Here we used a combination of minirhizotron tubes and in-growth cores fertilized with nitrogen to see if roots supplying greater levels of a limiting nutrient do indeed have extended lifespans. We found that for species with fine-root morphology, root lifespan was significantly extended by localized nitrogen fertilization, but this trend was not observed in species with coarse-root morphology. Finally, in Chapter 4 we investigated the role herbivory plays in fine-root lifespan. We know that herbivores and pathogens can significantly reduce root longevity, but how well roots are defended against such attacks remains unanswered. We therefore investigated the relationship between levels of fine-root soluble phenolics, a putative measure of chemical defenses against root herbivory, and specific factors that have been shown to be related to fine-root lifespan. Although we found significant correlations between fine-root phenolic concentrations and both root order and localized nitrogen availability, we were unable to find general utility in relating phenolic concentrations with factors that have been shown to extend fine-root lifespan. Combined, the research described in the following chapters represents a significant scientific contribution in furthering our understanding of the controls and constraints of fine-root lifespan.
Author: Nathan G. Swenson
Publisher: Springer Science & Business Media
ISBN: 1461495423
Category : Computers
Languages : en
Pages : 217
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Book Description
Functional and Phylogenetic Ecology in R is designed to teach readers to use R for phylogenetic and functional trait analyses. Over the past decade, a dizzying array of tools and methods were generated to incorporate phylogenetic and functional information into traditional ecological analyses. Increasingly these tools are implemented in R, thus greatly expanding their impact. Researchers getting started in R can use this volume as a step-by-step entryway into phylogenetic and functional analyses for ecology in R. More advanced users will be able to use this volume as a quick reference to understand particular analyses. The volume begins with an introduction to the R environment and handling relevant data in R. Chapters then cover phylogenetic and functional metrics of biodiversity; null modeling and randomizations for phylogenetic and functional trait analyses; integrating phylogenetic and functional trait information; and interfacing the R environment with a popular C-based program. This book presents a unique approach through its focus on ecological analyses and not macroevolutionary analyses. The author provides his own code, so that the reader is guided through the computational steps to calculate the desired metrics. This guided approach simplifies the work of determining which package to use for any given analysis. Example datasets are shared to help readers practice, and readers can then quickly turn to their own datasets.
