Taxonomk Classification of Humus Forms in Ecosystems of British Columbia First Approximation K. Klinka', R.N. Green', R.L. Trowbridge2 andL.E. Lowe3 'Ministry of Forests 3University of British Columbia Vancouver Forest Region 2357 Main Mall 355 Burrard Street University Campus Vancouver, B.C. V6C 2H 1 Vancouver, B.C. V6T 2A2 'Ministry of Forests Prince Rupert Forest Region P.O. Box 3369 Smithers, B.C.VOJ 2N0 1981 Province of British Columbia Ministry of Forests Canadian Cataloguing in Publication Data Main entry under title: Taxonomic classification of humus formsin ecosystems of British Columbia (Land management report, ISSN 0702-9861; no. 8) "Flrst approximation" Bibllography: p. ISBN 0-7719-8659-9 1. Humus - British Columbia. 2. Forest soils. British Columbla. I. Klinka, K., 1937- II. British Columbia. Ministry of Forests. 111. Series. S592.8.T38 631.4'17'0971 1 C81-902262-2 :c :c 1981 Provlnce of Brltlsh Columbla Publlshed by the Informatton Servlces Branch Mlnlstry of Forests Provtnce of Brltlsh Colurnbla Vtctorla. B.C V8W 3E7 Abstract A hierarchical system for the classification of humus florms is proposed. The proposedsystem has been devel- osped because of difficulties encountered with previous systems in discriminating between humus forms, and in relating them toecosystems. It is based on earlier systems, but takes advantageof extensive recent field experience chained from the Ecological Classification Programme in British Columbia. The classification and methodology for description are based on morphologicalproperties of humusforms. Keys tothe taxa and descriptions of representative humus form profiles are presented and are intended as practicalaids to ordering knowledge,stimulating re- searchand improving interpretations about humus forms andecosystems. The classification is considered to be a first approximation andis open to refinement upon testing and further studies. Non-conforming Materials ....................................................................................................... 44 Biota ......................................................................................................................................... 45 Soil Fauna ............................................................................................................................. 45 Soil Flora ............................................................................................................................... 47 Appendix I1 SAMPLINGMETHODS ANDOF ANALYSIS .............................................. 48 Sample Collection ..................................................................................................................... 48 Sample Preparation .................................................................................................................. 48 Bulk Density ............................................................................................................................. 49 Recommended Chemical Analysis ........................................................................................... 51 1. Organic Fraction Analysis ................................................................................................. 51 2 . Routine Analysis ............................................................................................................... 52 Appendix I11 SAMPLE OFTHE FORM USED IN HUMUS FORM DESCRIPTION ....... 54 Acknowledgements Appreciation is expressed to those who offered gui- dance, assistance and support in preparing this first ap- proximation. Valuablegeneral or specific comments were received from T.M. Ballard, Department of Soil Science, Universityof British Columbia; C. Tarnocai, Land Resource Research Institute, Department of Ag- riculture; T. Vold, Resource Analysis Branch, Ministry of Environment; and theEcological Program Staff, Min- istry of Forests, includingJ. Pojar (Prince RupertForest Region), F.C. Nuszdorfer(Vancouver Forest Region), W.J. Watt and C.A.S. Smith (Cariboo Forest Region),D. Lloyd and W. Erickson (Kamloops Forest Region), S.M. Hope and A.J. McLeod (Prince George Forest Region) and G.A. Utzig (Nelson Forest Region). Acknowledgementsfor assistance and co-operation are due to the members of the Working Group on Or- ganic Horizons, Folisols, and Humus Form Classifica- tion; to R.M. Laird, Ministry of Forests, for helping in preparing the final manuscript; to R. Carter and R.E. Carter for editing; toL. Skoda, Canadian Cartographics Ltd., and P. Frank, Ministry of Forests, for the prepara- tion of the figures; toK. Valentine, Agriculture Canada, for photomicrography; and to L. Leclerc and K.L. Vil- lalobos, Ministry of Forests, for the typing and prepara- tion of the manuscript. 1 readily determinable morphological features of humus Introduction forms (such as horizons, their thickness, colour, fabric, non-conforming materials and biota) for classification Background purposes. In addition to a detailed morphological de- Bernier’s (1968) descriptive outline of forest humus scription, some physical and chemical properties have form classification, adopted by the Canadian Soil Survey been determined.A meaningful set of chemical analyses Committee (Dumanski (ed.) 1978), has been used until for humus materials is still the subject of research. In recently by the British Columbia Ministry of Forests, in addition, how themorphological properties correlate classifying humus forms. Because humus forms can be with quantitative properties remains to be tested, and applied as differentiating oraccessory characteristics for precise definitions of class boundaries for horizons and various taxain the system of ecosystem classification usedtaxa still need to be determined by laboratory analyses. by the British Columbia Ministry of Forests, this classifi- The nomenclature employed for classes (taxa) at the cationsystem has greatly enhanced their ecological highest level of generalization is based on three interna- studies. However, during its decade of use, weaknesses tionally recognized terms: mor, moder and mull.Names have been exposed concerning definitions oforganic for taxa oflower level categories are formedby prefixing horizons, methods of describing humus forms, termin- modifiers, formed mostly from Greek or Latinroots. ology, treatment of non-conforming materials, the defin-These modifiers suggest some of the more important ition of moder- humus forms, the tentative classification properties and, where possible, the taxonomic differ- status of humus forms associated with semi-terrestrial entiae for a particularclass. Such a system has been used andgrassland ecosystems, and inconsistencies in the consistently by Wilde (1966, 197 1) for humus forms and hierarchical structure. by Soil Survey Staff(197.5) in soil taxonomy. A review of existing c1a:rsificationsof humus forms used in the U.S.A. (Hoover and Lunt 1952, Wilde 197 1) Importance of the Taxonomy andin Europe (Hartmann 1952, Kubiena 19.53, Duchaufour 1960) indicated that they could not advan- Within the constraints imposedby both environmental tageouslyreplace Bernier’s system becausethey em- and management objectives, the general goal of forestry bodied similar weaknesses. In particular, the terms used management is to utilize and maintain the productivityof to describe and classify humus forms were found to be the ecosystems under- management and,when possible, inconsistent: expressions beingused internationally were to increase productivity. Because of the important rela- found to have two or more meanings, andthe same tionships belween the properties of humus forms and entities were known under several names. Doubts have forest productivity, meetingthis goal requires knowledge been expressed as towhether thesenames are really regarding humus forms and,in addition, a classification synonymous (Bernier 1968.. Howard 1969, Wilde I97 I). system which will permit the application of that know- Another difficulty is that even when the names of those ledge to similar humus forms in areas which have not humus formsrecognized by Kubiena ( 1953)or others are been studied in detail. The taxonomic classification, in employed, they are not applied uniformly. The same is other- words, provides an important tool which can be true of the horizon designation: the terms are not used used for developing interpretations for forest manage- uniformly nor do authorsclearly statehow they are using ment. The keys to the taxa and the descriptions of rep- the terms (Babel 197.5). resentative humus form profiles can be used as practical So, because of the weaknesses in the existing system aids in ordering knowledge and for improving interpre- andthose used elsewhere., the Ecological Programme tations about humus forms andecosystems. Staff’ suggested that a revision of Bernier’s classification Since 1975, the Ministry of Forests has been directing system be initiated. attention to the systematic development of a common scientific base for site (ecosystem)- specific management Approach of the forest resource (Schmidt 1978). The taxonomic classification system which is presented here is expected Ideally, a taxonomicclassification of humusforms to contribute to that goal. should ultimately be based011 the physical, chemicaland biological properties of humus forms which correlate readily with identifiable morphological properties. How- Synopsis ever, because of present inadequaciesin the existing data Inthe first part ofthis report, the taxonomicclassifica- base, purely morphological properties had to