PLANT LITTER : decomposition, humus formation, carbon sequestration.

Preface
Contents
1 Introduction
	1.1 Overview of Plant Litter Decomposition
	1.2 A Short Retrospective
	1.3 The Ecological Significance of Litter Decomposition and the Formation of Humus
	1.4 Factors Influencing Decay and Humus Formation
	1.5 Accumulation of Humus and Nutrients
	1.6 The Contents and Organization of the Book
	1.7 Motives for the Present Synthesis
	1.8 New Developments Included in the Fourth Edition
	References
2 Decomposition as a Process—some Main Features
	2.1 Litter Decomposition—a Set of Different Processes Including Synthesis of New Compounds
	2.2 Definition of Litter Decomposition
	2.3 Ash Dynamics
	2.4 Nutrients Limiting for Litter Decomposition—some Observations
	2.5 Degradation of the Main Groups of Organic Compounds in Foliar Litter
		2.5.1 Degradation and Leaching of Soluble Organic Substances
		2.5.2 Degradation of Non-Lignified Organic Substances
		2.5.3 A Pattern of Degradation of the Main Organic Compounds in Pine Needle Litter
		2.5.4 Some Chemical Changes during Decomposition that May Be in common for Foliar Litter over Species and Genera
		2.5.5 Pattern for Main Organic Compounds Based on AUR—Gravimetric Analyses of Lignin
		2.5.6 13C-NMR Analysis Applied to Decomposing Foliar Litter
	2.6 Factors Regulating Degradation of Lignin/AUR
		2.6.1 Potential Effects and Possible Interactions on Lignin/AUR Degradation
		2.6.2 Effects of Litter Mn Concentration on Lignin/AUR Degradation and Litter Mass Loss
		2.6.3 Effects of N on Lignin/AUR and Late-Stage Litter Degradation
	2.7 Proposed Models for Decomposition from Newly Shed Foliar Litter to the Humus Stage
		2.7.1 Three-Stage Model
		2.7.2 The Two-Stage Model
		2.7.3 In common for both Models—the Humus-Near or Limit-Value Stage
	References
3 Decomposer Organisms
	3.1 Introduction
	3.2 General Properties of a Given Microbial Population
	3.3 The Degradation of the Main Polymers in Litter
		3.3.1 Degradation of Cellulose
		3.3.2 Degradation of Hemicelluloses
		3.3.3 Degradation of Lignin
	3.4 Degradation of Fibers
		3.4.1 Bacteria
		3.4.2 Soft-Rot
		3.4.3 Brown-Rot
		3.4.4 White-Rot
	3.5 Mycorrhizae
	3.6 Ecological Aspects
	References
4 Initial Litter Chemical Composition
	4.1 Introduction
	4.2 Organic Chemical Components of Plant Litter and Fiber Structure
		4.2.1 Organic Chemical Components
		4.2.2 Fiber Structure
	4.3 Nutrient and Heavy Metal Concentrations in Newly Shed Litter
		4.3.1 General Features
		4.3.2 Nutrient Resorption and Withdrawal Efficiency
		4.3.3 Nutrient Concentration Change; Green Foliage versus Brown Litter
	4.4 Factors Influencing Litter Chemical Composition
		4.4.1 General Factors
		4.4.2 Nutrients, Heavy Metals, and AUR in Needle Litter of two Conifers, Pine, and Spruce Spp—two Case Studies in Climate Gradients
		4.4.3 Influence of Soil Properties
		4.4.4 Influence of Tree Age
	4.5 Several Deciduous and Coniferous Leaf Litter Species
		4.5.1 Variation in a Eurasian—Global Gradient—Focus on Nitrogen
		4.5.2 Coniferous versus Deciduous Genera/Species and Influence of Species—an Old Concept
		4.5.3 General and Global Relationships
	4.6 Wood, Cones, and Fine-Root Litter
	4.7 Anthropogenic Influences on Initial Litter Composition
		4.7.1 N-Fertilized Scots Pine and Norway Spruce Monocultures
	References
5 Changes in Substrate Composition During Decomposition
	5.1 Introductory Comments
	5.2 Organic Chemical Changes during Litter Decomposition
		5.2.1 Traditional Analytical Fractions
		5.2.2 Relationships between Holocellulose and AUR
		5.2.3 13C–NMR Technique
	5.3 The Dynamics of Mn, Ca, K, and N
		5.3.1 Manganese Dynamics
		5.3.2 Calcium Dynamics
		5.3.3 Potassium Dynamics
		5.3.4 Nitrogen Concentration Dynamics over a Climatic Gradient
	5.4 A Special Study on Minor Elements/Heavy Metals—Early to Late-Stage Decomposition
		5.4.1 Concentration Dynamics
	References
6 Role of Chemical Constituents in Regulating Decay Rates and Stable Fractions: Effects of Initial and Changing Chemical Composition on Decomposition and Organic Matter Accumulation
	6.1 Introduction
	6.2 Some Nutrients and Compounds in Litter Influencing Decomposition Rates
	6.3 Two Models with three and two Stages Applied to Litter Species of Different Chemical Composition
		6.3.1 A Three-Phase Model—Litter Decomposition Pattern Type I
		6.3.2 A Two-Phase Model—Litter Decomposition Pattern Type II
		6.3.3 Decomposition Related to Lignin Monomers across Litter Species—a Molecular Level and a Possible Relationship to N
		6.3.4 Some Comparisons of Effects of Mn and N in Lignin-Dominated Phases—Litter Decomposition Pattern Type I versus Type II
	6.4 Decomposition in Early and Late Stages as Related to 13C-NMR Analysis
	6.5 Litter at the Humus-Near or Limit-Value Stage
		6.5.1 General Comments
		6.5.2 General Relationships
		6.5.3 Do Limit Values Indicate a Stable Fraction? Can we Relate a Production of Leachable Organic Components from the Stable Fraction to Litter Chemistry?
	References
7 Climate Gradients. Substrate Quality versus Climate and their Interactions
	7.1 Introduction
	7.2 Microbial Response to Temperature and Moisture
	7.3 How Sensitive to Climate is Decomposition of Foliar Litter?
	7.4 Litter and Litter Fractions Dominated by Lignified Tissue
		7.4.1 Decomposition of Type II versus Climate and Substrate in Foliar Litter
		7.4.2 Decomposition Type I of Foliar Litter, Late Stage versus Climate and Substrate Quality
	7.5 Decomposition Dominated by Non-Lignified Tissue—Decomposition Type I in the Early Stage
		7.5.1 Local Scots Pine and Pine Species Litter—a North European Climate Gradient
		7.5.2 Unified Scots Pine Litter in a European—North American Climate Gradient
		7.5.3 Multispecies to Genera. A Gradient across Asia and Europe—First-Year Mass Loss
	7.6 Root Decomposition along Climate Gradients—First-Year Mass Loss
		7.6.1 Scots Pine, Lodgepole Pine, and Norway Spruce, Combined Data and Single Species
		7.6.2 Several Species
	7.7 Two Northern European Climatic Gradients
	References
8 Decomposition of Root Tips, Fine Roots, and Coarse Roots
	8.1 Introduction
	8.2 Root Classification and Properties
	8.3 Methods to Study Roots
		8.3.1 Amount of Fine Roots
		8.3.2 Decomposition of Roots
	8.4 Root Tips—Class 1 Roots—and their Decomposition. Early and Late Stages as well as Limit Values
		8.4.1 Initial Chemical Composition
		8.4.2 Decomposition Patterns and Rates versus Substrate Quality and Climate Factors. A Model for Rate-Regulating Factors
	8.5 Root Decomposition, Early and Late Stages as well as Limit Values for Fine Roots, Classes 1 thru 6
		8.5.1 Some General Patterns across Root Classes 1 thru 6
	8.6 Decomposition of Fine and Coarse Roots—Studies Based on Root Diameter
		8.6.1 Mass-Loss Rates and Decomposition Patterns—Climatic Gradients and Global Data
		8.6.2 Changes in Chemical Composition
	8.7 Conceptual Models for Root Decomposition
	References
9 Decomposition of Cones and Woody Litter
	9.1 Introduction
	9.2 Inputs to the Forest Floor—Cones and Twigs/Branches
	9.3 Cones—Decomposition
		9.3.1 Experimental Design and Sampling
		9.3.2 Mass Loss and Chemical Changes
	9.4 Woody Litter—Decomposition
		9.4.1 Methods
		9.4.2 Decomposition Rates versus Climate
		9.4.3 Carbon Dioxide Release
		9.4.4 Organic Chemical Changes
		9.4.5 Changes in Nutrient Concentrations
	References
10 Models that Describe Decomposition of Foliar Litter and Roots
	10.1 Introduction
	10.2 Two Commonly Used Models
	10.3 Models
		10.3.1 Single Exponential
		10.3.2 Asymptotic Models
	10.4 Some Dominant Influencing Factors Related to Type of Model
		10.4.1 The Three-Stage Model (Decomposition Type I) May Be Useful to Clarify Details in the Concept ‘Decomposition Pattern.’
		10.4.2 The Two-Stage Model May Be Useful to Clarify Details in Decomposition Pattern Type II for Foliar Litter
		10.4.3 Model for Class 1 Roots
	10.5 Degradation of Specific Bonds May Be Followed and their Rates Calculated (13C-NMR)
	10.6 Influences on the Limit-Value Stage plus Variation in Pattern–General Relationships
	References
11 What Factors May Influence the Accumulation of Humus Layers?
	11.1 Introduction
	11.2 Accumulation of Stabilized Humus/Carbon in Organic Layers of Boreal and Temperate Forests
		11.2.1 Humus and Organic Layers—Do they Increase in a Predictable Way?
	11.3 Variation in Carbon Sequestration Rates; Effects of Tree Species, Soil Properties and N Fertilizer on the Organic Layer
		11.3.1 General Comments
		11.3.2 Large-Scale Comparisons among Tree Species over Northern Europe
		11.3.3 Accumulation of SOM-C. Coniferous Forests in Climate Gradients
		11.3.4 Are there Effects of N Fertilizer?
		11.3.5 Effects of Soil Texture and Mineral Soil Nutrients and Organic Layers
		11.3.6 Humus Layer Stability versus its Turnover
	11.4 Carbon in the Mineral Soil
		11.4.1 Does the Amount of Organic Matter in the Mineral Soil Change?
		11.4.2 Organic Matter Mixed into the Mineral Soil
		11.4.3 Is there any Effect of Disturbance?
	References
12 Estimating Carbon Sequestration Rates on a Regional Scale
	12.1 Long-Term Accumulation of Carbon in Organic Layers (O Horizon)—General Comments
	12.2 Influences on Carbon Sequestration Rates in Forested Land—Regional Level
		12.2.1 Influences at Undisturbed Sites and Anthropogenic Influence
		12.2.2 General Consideration as Regards a Database for Regional Modeling
	12.3 Two Case Studies
	12.4 Case Study for a Region. Remaining Stable Fraction—a Theory and a Possible Regional Approach
		12.4.1 Short Background
		12.4.2 Geographical Database
		12.4.3 Potential Carbon Sequestration Rates and Effect of Tree Species
		12.4.4 The Effect of Tree Species on Carbon Sequestration Rates in the Humus Layer
		12.4.5 Error Sources in the Limit-Value Approach
	12.5 Case Study for a Region—Direct Measurements of Humus Depth
		12.5.1 Background
		12.5.2 General Design of the Humus Inventory
		12.5.3 Scaling up from Field Measurements on Humus Depth in Plots to C Sequestered on Country Level—Overview
		12.5.4 Changes in Organic Layer Thickness over Time
		12.5.5 Calculations of Carbon Bulk Density in the Humus Layer
		12.5.6 Calculated Carbon Sequestration Rates, some Patterns, and their Possible Causes
		12.5.7 Possible Sources of Error in Estimates of Carbon Sequestration Rates
		12.5.8 Manganese Concentration in the Humus Layer Is Related to Higher Humus Decomposition Rates
	12.6 Carbon Sequestration Rates in the Case Studies Compared to Quantitative Measurements in single Stands and Chronosequences as well as among them
		12.6.1 Gravimetric Measurements
		12.6.2 Carbon Dioxide Budgets
	12.7 Carbon Sequestration in Mineral Soil—Observations on a Regional Scale
		12.7.1 Different Sequestration Patterns?
	12.8 Regional Carbon Sequestration in a Global Context
	References
13 Comments on Methods for Litter Decomposition Studies
	13.1 Introduction
	13.2 Design of Litterbag Experiments and some Calculations
	13.3 Overview of Common Analytical Methods for Organic Compounds in Litter with Focus on Lignin
		13.3.1 Introduction
		13.3.2 Methods for AUR, Lignin, and Carbohydrates
	13.4 What Information May the Different Approaches Give?
		13.4.1 Comments on Information we Can Reach at present
	References
Appendix A Scientific Names of Vascular Plants
Gymnosperms
Angiosperms
-4pt-  Glossary