detritus, pools, fluxes, ecosystems, decomposition, biotic factors, abiotic factors, nutrient cycling, humus biosynthesis, post-graduate students, soil biology, biochemistry, soil sciences, ecosystem structure, function
The present book is a detailed assessment of the pools and fluxes of detritus in aquatic and terrestrial ecosystems. Besides presenting a comprehensive analysis of the process of detritus decomposition, the book gives an exhaustive account of the biotic and abiotic factors affecting the rate of detritus decomposition. Portrayal of the role of decomposition in nutrient cycling and delineation of the contemporary concepts of humus biosynthesis are the noteworthy features of this book. The book would be serve the needs of post-graduate students having Ecology as one of their major subject and researchers engaged in soil biology and biochemistry, soil sciences and ecosystem structure and function.
Preface Most of the Net Primary Production (annual gain of energy and matter by the plant sub-system) is not consumed by herbivores, but is returned to the environment as detritus which plays critical roles in organizing and sustaining ecosystems. In addition to its effects on trophic structure and dynamics, detritus physically alters habitats thereby facilitating some species and inhibiting others. It goes through a series of changes with time that are mediated by decomposers through the involvement of extracellular enzymes whose synthesis is affected by all the factors that affect microorganisms in soil, such as moisture, temperature, and available nutrients. After release, the activity of soil enzymes is regulated primarily by litter chemistry, substrate availability and temperature. Through their contribution to the recycling of essential chemical elements such as nitrogen and phosphorus (that are in limited supply for primary producers), decomposers play a key role in the primary productivity of ecosystems.
1.1. Characteristics and categories 1.2. Litter Patterns of accumulation Successional trends Seasonal variations Fluctuations in accumulation 1.3. Dissolved organic matter Sources of DOM Fluxes of DOM 1.4. Woody detritus 1.5. Soil organic matter
2.1. The Physical environment Light Soil temperature Water dynamics 2.2. Chemical environment Production of phytotoxins 2.3. Biological environment Trophic dynamics Community structure Biodiversity
3.1.Processes Leaching Fragmentation/Comminution Catabolism Decomposition models 3.2. Patterns Litter decomposition Root decomposition Limit values for decomposition Decomposition pattern in ecosystems
4.1. Substrate quality Litter quality Soil organic matter (SOM) quality 4.2. Decomposer community Soil animals Soil microorganisms Terrestrial fungi Actinomycetes Bacteria
5.1. Nature and role of soil enzymes General account Role in terrestrial ecosystems Role in aquatic ecosystems 5.2. Environmental conditions and microbial enzyme activity
Preface
Chapter 1.Nature and composition of detritus
1.1. Characteristics and categories
1.2. Litter
Patterns of accumulation
Successional trends
Seasonal variations
Fluctuations in accumulation
1.3. Dissolved organic matter
Sources of DOM
Fluxes of DOM
1.4. Woody detritus
1.5. Soil organic matter
Chapter 2.Effects of detritus on environment
2.1. The Physical environment
Light
Soil temperature
Water dynamics
2.2. Chemical environment
Production of phytotoxins
2.3. Biological environment
Trophic dynamics
Community structure
Biodiversity
Chapter 3.Decomposition: Processes and patterns
3.1. Processes
Leaching
Fragmentation/Comminution
Catabolism
Decomposition models
3.2. Patterns
Litter decomposition
Root decomposition
Limit values for decomposition
Decomposition pattern in ecosystems
Chapter 4.Biotic factors of detritus decomposition
4.1. Substrate quality
Litter quality
Soil organic matter (SOM) quality
4.2. Decomposer community
Soil animals
Soil microorganisms
Terrestrial fungi
Actinomycetes
Bacteria
Chapter 5.Soil enzymes and detritus decomposition
5.1. Nature and role of soil enzymes
General account
Role in terrestrial ecosystems
Role in aquatic ecosystems
5.2. Environmental conditions and microbial enzyme activity
Chapter 6.Abiotic factors of detritus decomposition
6.1. Soil Moisture
Influence on decomposer organisms
Influence on rate of decomposition
6.2. Temperature
Influence on decomposer organisms
Influence on rate of decomposition
6.3. pH
6.4. Fire
6.5. Soil atmosphere
6.6. Soil texture and organic carbon
6.7. Disturbance
Chapter 7.Humus biosynthesis
7.1. Nature of humic substances
Types and properties
Humic acids
Fulvic acids
Humin
7.2. Synthesis of humic substances
Humic polymer model
Ligin theory
Polyphenol theory
Sugar-amine condensation theory
Molecular aggregate model
Degradation of plant residues
Interactions of degradation products
7.3. Forms of humus
7.4. Role of humic substances
Soil fertility
Plant growth
Chapter 8.Nutrient cycling
8.1. Nutrient resorption
Growth form and resorption
Nutritional controls of resorption
Resorption proficiency
Biochemistry of resorption
8.2. Nutrient leaching
8.3. Nutrient mineralization
References
Index
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