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Mull and mor (müller-hesselman) in relation to the soil water regime of a forest


The distribution of mull and mor, in an area which is believed to have borne forest for a number of centuries at least, led to investigations into the reasons for their development.

Although the term forest-floor type has been substituted for humus type, mull and mor are used in the Müller-Hesselman sense.

There appeared to be no obvious relationship between the distribution of the various forest-floor subtypes and the results of chemical analyses and pH determinations on soil samples.

Where free CaCO3 occurred in the A1-horizon, a mull forest floor had developed even on coarse sand and the associated herb flora differed only slightly from that occurring on very acid mull. As the manner in which lime influences most soil processes is still unknown, the areas in which free CaCO3 occurs were excluded from the investigations.

Assessments of various other soil characteristics were made and the frequency of association of the various categories of these characteristics ascertained.

It is concluded that the colour of the upper part of the A1-horizon and its degree of leaching are related to its texture, and that the forest-floor subtypes are more closely related to soil texture than to soil colour or degree of leaching.

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Minderman, G. Mull and mor (müller-hesselman) in relation to the soil water regime of a forest. Plant Soil 13, 1–27 (1960).

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