Plant litter : decomposition, humus formation, carbon sequestration / Björn Berg, Charles McClaugherty.

Format:

Book

Author/Creator:

Berg, Björn, 1943-

Contributor:

McClaugherty, Charles, 1951-

Language:

English

Subjects (All):

Plant litter--Biodegradation.

Plant litter.

Soil ecology.

Physical Description:

xii, 286 pages : illustrations ; 24 cm

Place of Publication:

Berlin ; New York : Springer, [2003]

Summary:

The present book gives a modernized and comprehensive overview of the degradation of major litter components as well as the sum of processes when forest plant litter decomposes, releases nutrients and turns into humus. Covering mainly boreal and temperate forests, the book gives a synthesis of the different sub-processes on the basis that decomposition is microbially mediated and develops a system in the decomposition processes leading to chemical changes in litter. Further, it introduces a conceptual model for litter transformations from litter fall until the decomposing litter accumulates as humus. The effects of substrate quality, climate, and their interactions on decomposition are presented as well as examples of litter types that break the basic pattern. A system is suggested for humus accumulation rates among forest systems, a system that may be a starting point for estimates of carbon sequestration in forest systems.

Contents:

1.1 Overview of plant litter decomposition 1

1.2 A short retrospective 2

1.3 The ecological significance of litter decomposition and the formation of humus 3

1.4 Factors influencing decay and humus formation 4

1.5 Accumulation of humus and nutrients 5

1.6 The contents and organization of the book 6

1.7 Motives for the present synthesis 9

2 Decomposition as a process 11

2.1 Litter decomposition - a set of different processes 11

2.3 Degradation of the main groups of compounds in litter 15

2.3.1 Degradation and leaching of soluble organic substances 15

2.3.2 Patterns of degradation of the main organic compounds in litter 15

2.4 A model for decomposition from newly-shed litter to humus-near stages 18

2.4.1 The early decomposition stage: degradation of solubles and non-lignified carbohydrates 20

2.4.2 The late stage: lignin-regulated decomposition phase 20

Effect of N on lignin degradation 22

2.4.4 Humus-near stage in litter decomposition - limit values 26

What may cause the decomposition to cease? 29

3 Decomposer organisms 31

3.2 General properties of a given microbial population 32

3.3 The degradation of the main polymers in litter 34

3.3.1 Degradation of cellulose 34

3.3.2 Degradation of hemicelluloses 37

3.3.3 Degradation of lignin 37

Lignin degradation by white-rot fungi 38

Lignin degradation by brown-rot fungi 39

Lignin degradation by soft-rot fungi 41

Enzymes directly affected by Mn concentration in the substrate 42

Effect of N starvation on lignin metabolism 42

Effect of the C source on lignin degradation 43

3.4 Degradation of fibers 43

3.4.1 Bacteria 43

3.4.2 Soft-rot 44

3.4.3 Brown-rot 44

3.4.4 White-rot 45

3.5 Mycorrhizae 45

3.6 Ecological aspects 46

4 Initial litter chemical composition 49

4.2 Organic-chemical components of plant litter and fiber structure 50

4.2.1 Organic-chemical components 50

4.2.2 Fiber structure 52

4.3 Nutrient concentrations in newly shed litter 54

4.3.1 General features 54

4.3.2 Nutrient resorption 54

4.3.3 Nutrients in Scots pine needle litter - a case study 57

Annual variation at one site 57

Variation among Scots pine sites and in a transect 59

4.3.4 Several deciduous and coniferous leaf litters 61

Influence of soils 64

Variation over a climatic transect 66

4.3.5 A comparison of some common species 66

4.3.6 How much do N and lignin concentrations vary locally and regionally? 68

4.4 Wood and fine root litter 70

4.5 Anthropogenic influences on initial litter composition 70

4.5.1 N-fertilized Scots pine and Norway spruce monocultures 71

4.5.2 Heavy metal pollution and initial litter chemical composition 76

5 Changes in substrate composition during decomposition 79

5.2 Organic-chemical changes during litter decomposition 80

5.2.1 A case study on Scots pine needle litter 80

Water soluble fraction 80

Ethanol soluble fraction 81

Cellulose 82

Hemicelluloses 83

Lignin 83

5.2.2 Other species 84

5.2.3 Relationships between holocellulose and lignin 84

5.3 Nutrient and heavy metal concentrations during decay 85

5.3.1 Changes in concentrations of elements in decomposing litter 85

Scots pine 86

5.4 Special studies on K, N and lignin dynamics 90

5.4.1 K concentration dynamics 90

5.4.2. N concentration dynamics over a climatic transect 93

5.4.3. Lignin dynamics in a climatic transect 100

6 Influence of chemical variation in litter on decomposition 107

6.2 A three-phase model applied to litters of different chemical composition 108

6.2.1 Overview of the model 108

6.2.2 Initial decomposition rates for newly shed litter - early decomposition stage in plant litter 109

How can initial rates be described? 110

Initial chemical composition and different indices related to initial decomposition rates 113

Comments on a deviating foliar litter type: spruce 116

6.2.3 Decomposition in the late stage - lignin-regulated phase 118

The late decomposition stage 118

Effect of lignin and N on litter decomposition rates 118

Mass-loss rates of lignin as compared to initial litter N levels 119

The lignin fraction 120

The biological regulation and the chemical mechanisms 122

How should we regard the retardation of litter decomposition caused by lignin? 122

Some different lignin-related decomposition patterns among litter types 124

6.2.4 Litter at a humus-near or limit-value stage 128

General relationships 129

Groups of litter have different empirical relationships 133

6.3 Does chemical composition influence leaching of compounds from humus? 134

7 Climatic environment 137

7.2 Microbial response to temperature and moisture 138

7.3 Early-stage decomposition of Scots pine needle litter 138

7.3.1 Decomposition at one site 138

7.3.2 Decomposition over transects 141

Scots pine monocultures 142

Monocultural pine stands of different species 144

7.3.3 Soil warming experiments 147

7.4 Effect of substrate quality on mass-loss rates in Scots pine transects 149

7.4.1 Early stage 149

7.4.2 Late stage 151

7.5 Climate and decomposition of Norway spruce needle litter 154

7.5.1 Climate versus first-year mass loss 154

7.5.2 Late stage 157

7.6 Climate and decomposition of root litter 159

7.7 A series of limiting factors 160

7.8 Climate and the decomposition of humus and litter in humus-near stages 161

8 Influence of site factors other than climate 163

8.2 Soil factors 163

8.2.1 Soil texture 163

8.2.2 Forest floor type 165

8.2.3 Local topography 165

8.3 Nutrient availability 167

8.4 Plant community composition and structure 169

8.4.1 Effect of litter species composition 170

8.4.2 Community structure and development 170

8.6 Carbon dioxide levels 171

9 Decomposition of fine root and woody litter 173

9.2 Woody litter decomposition 174

9.2.1 Methods 174

Decay classes for coarse wood (logs) 174

Mass loss rates: percent loss and decay constants (k) 176

Estimating mass loss in coarse woody litter 177

9.2.2 Decomposition rates versus climate 177

9.2.3 Carbon dioxide release 179

9.2.4 Organic chemical changes 179

9.2.5 Changes in nutrient concentrations 181

9.3 Fine root decomposition 184

9.3.1 Fine root litter 184

Amounts of litter 184

Chemical composition of fine roots 185

9.3.2 Mass loss rates 185

9.3.3 Changes in chemical composition 187

10 Models that describe litter decomposition 191

10.2 Two main kinds of empirical models 193

10.3 Models used to describe decomposition of whole litter as a single or "unified" substrate 194

10.3.1 Single exponential 194

10.3.2 Asymptotic model 194

10.4 Dominant factors that influence the unified-substrate models 195

10.4.1 Extent and quality of the data set 196

10.4.2 Substrate quality 196

10.5 Models based on two or three substrate-quality fractions 201

10.5.1 The double exponential 201

10.5.2 The triple exponential 202

11 Decomposition and ecosystem function 203

11.2. Humus is accumulating in undisturbed forest ecosystems 204

11.2.1. How far can humus accumulate? 204

11.2.2 A mechanism for humus accumulation under undisturbed conditions 206

Litter chemical composition and limit values 206

Nitrogen, Mn, and heavy metals may be system-specific indicators 208

Additional stabilizing factors 208

Litter components change with stand development 208

What litter components can form humus? 210

11.2.3. An accumulation mechanism can be validated 212

Direct humus measurements 213

Different species - different N levels - predicted differences in paired stands of Scots pine / Norway spruce and Douglas-fir / red alder 216

Comparison between estimated N concentration at the limit value for decomposition and that measured for humus in the same stand 218

11.2.4 Can different ecosystems accumulate humus at different rates? 218

Different species 218

Differing litter chemical composition 221

11.3 How stable is humus? 222

11.3.1 Do limit values indicate a complete stop in litter decomposition? 222

11.3.2. Four classes of humus turnover 223

Humus decomposition - undisturbed systems 223

Disturbances of decomposition rates - some specific cases - mycorrhizae in natural systems 225

Disturbances of decomposition rates: fire, soil manipulation, and drainage 226

Disturbances of decomposition rates: systems with high N-loads 227

11.3.3 Possible effects of increased temperature on humus decompositionan artifact? 228

11.4 Storage of nutrients in humus 229

11.4.1 What amounts of nutrients can be stored in accumulating humus? 229

Nitrogen 229

11.5 A climate - change scenario 232

11.5.1 Fennoscandia and the Baltic basin 232

11.5.2 Is there a general relationship between climate and foliar litter N concentration under boreal/temperate conditions? 233

Foliar litter fall is richer in N under warmer and wetter conditions 233

Litter N concentrations increase faster relative to litter mass loss under warmer and wetter conditions 235

11.5.3 How large can a change in humus accumulation be? 235

12 Human activities that influence decomposition 239

12.2 Global warming 240

12.3 Regional pollution 241

12.3.1 Atmospheric N and S deposition 241

12.3.2 Heavy metals 243

12.3.3 Nuclear radiation, ozone, and proximity to urban centers 244

12.4 Effects of selected forest management practices 245

12.5 Long-term perspective 246

Appendix II. Scientific names of vascular plants 253

II.1 Gymnosperms 253

Firs 253

Hemlocks 253

Pines 253

Spruces 254

II.2 Angiosperms 254

Alders 254

Aspen 254

Beeches 254

Birches 254

Grasses 254

Maples 255

Oaks 255

Other woody plants 255

Appendix III. Site descriptions 257

Strasan, Sweden 257

Jadraas, Sweden 257

Black Hawk Island, Wisconsin, USA 257

Harvard Forest, Massachusetts, USA 258.

Notes:

"With 76 figures and 64 tables."

Includes bibliographical references (pages [259]-278) and index.

ISBN:

3540443290

OCLC:

51867942