Humus Forms •
morphology •
microbiology •
Wald •
Norddeutsches Tiefland
Humus forms in forests of the northern German lowlands were
investigated on the basis of morphological, soil chemical and
microbiological characteristics. Existing classifications for humus
forms in temperate forest ecosystems were reviewed and compared, and
the historical development of the German classification was
compiled. Morphological aspects of humus forms in intensively managed
forests are presented. A soil moisture index is suggested which has
been harmonized between the site mapping systems of the lowlands, and
which provides a systematic approach to enter the classification of
humus forms. The study then analyzed the chemical data of the German
large-scale soil inventory with respect to humus forms, and
additionally investigated a representative subset of soil inventory
points for microbiological activity. Decomposition types were derived
and compared to humus forms and soil chemical data. The leveling
effects of pollutant deposition on the soil chemical condition in
central European forest ecosystems were confirmed. These effects do
not correspond to the range of humus forms and microbiological
activity types that were found. It can be concluded that the commonly
used chemical indicators for the soil condition (C/N, base saturation
and pH) do not sufficiently reflect the nutrient and productivity
status of forest soils.
1 Introduction
1.1 Humus in forest soils
1.2 Processes of decomposition
1.3 Humus forms
1.4 Research objectivs
2 Classification of humus forms
2.1 German classification of humus forms
2.1.1 Morphological classification of humus forms in forest site and soil
mapping
2.1.2 Humus form and type of soil condition in the north-eastern German site
mapping system
2.2 French classification of humus forms
2.3 Canadian classification of humus forms
2.4 Comparison of the German, French and Canadian approaches
2.5 Regional distribution of humus forms in forests of the northern German
lowlands
2.5.1 Regionalization of grid point inventory data
2.5.2 from the Mapping results in the north-eastern lowlands
3 Methods
3.1 Study sites
3.1.1 German National Forest Soil Inventory
3.1.2 Inventory sites for respiration measurements
3.2 Ecological site descriptors
3.3 Soil chemical indicators of humus quality
3.3.1 A/B status: acidity and nutrient availability
3.3.2 N status: carbon-related N storage (C/N ratio)
3.4 Microbiological indicators of humus quality - measurement of soil
respiration
3.4.1 Introduction to soil respirometry
3.4.2 Respiratory parameters and graphical analysis of respiration curves
3.4.3 Sampling
3.4.4 Sample storage and processing
3.4.5 Respirometers, laboratory conditions, data set I+II
3.5 Statistical treatment of the data
4 Morphological aspects of humus forms
4.1 Soil moisture and humus forms
4.1.1 Development of a moisture index for the northern German lowlands
4.1.2 Comparison between moisture index and humus form
4.2 Humus content of humus horizons
4.3 Difficulties with the identification of humus forms in managed forests
4.3.1 F-Mor and disturbed humus profiles
4.3.2 The degree of podsolization as an aid to distinguish between
low-activity humus forms
4.3.3 Humus forms on afforestation sites
4.3.4 Grassmoder in mature Scots pine stands
4.3.5 Effects of the artificial lowering of the ground water
4.4 Thickness and carbon storage of the forest floor humus layer
4.5 Concluding remarks concerning humus morphology
5 Soil chemical characteristics of humus forms
5.1 Type of soil condition and morphological humus form
5.1.1 Mull
5.1.2 Mullmoder
5.1.3 Moder
5.1.4 Mormoder
5.1.5 Mor
5.2 Soil chemical parameters and type of soil condition
5.3 Acidity and N status of humus horizons
5.3.1 (L)F horizon
5.3.2 H horizon
5.3.3 A horizon
5.4 Discussion
6 Microbiological indicators of humus quality
6.1 Microbiological indicators for humus horizons
6.1.1 L horizon
6.1.2 F horizon
6.1.3 H horizon
6.1.4 A horizon
6.1.5 Concluding remarks
6.2 Decomposition type
6.2.1 Data set I: north-western German lowlands
6.2.2 Data set II: north-eastern German lowlands
6.3 Soil respiration and soil chemistry
6.3.1 Respiratory parameters and soil chemical properties of humus forms
6.3.2 Decomposition type and type of soil condition
6.4 Discussion
7 Integrated aspects of humus form classification
7.1 Soil respiratory data in humus form classification
7.1.1 Research objective
7.1.2 Methods
7.1.3 Sampling
7.2 Anthropogenic effects on the development of humus forms
7.2.1 Role of steady state in humus dynamics in intensively managed forests
7.2.2 Effects of air pollutants
7.2.3 Climate change
7.3 Improvements of the present German classification of humus forms
8 Conclusions
9 Summary
10 Zusammenfassung
11 List of tables
12 List of figures
13 References
Appendix
This publication presents a study of Humus types from forests of the
northern German lowlands based on morphological, soil chemical
and microbiological characteristics. The study proposes a soil
moisture index and presents chemical data for these soils and presents
data on microbiolgical activities in these soils. Decomposition types
were derived and compared to humus forms and soil chemical data.
