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The soil under the microscope: the optical examination of a small area of Scots pine litter (Pinus sylvestris L.)

De
144 pages
This is an English translation of three papers in French which have been published in scientific journals in 1984, 1985 and 1988. The present document describes the components of a moder humus profile under Scots pine, as they can be observed under a dissecting and a light microscope. Plant litter debris, roots and animal feces were collected over a small area (5 x 5 cm) in order to be sectioned and stained. All animals and microbes (fungi, bacteria, micro-algae) collected within a small area of litter (5 x 5 cm) were identified to the finest possible taxonomic level. Gut contents were analyzed and compared with the composition of the immediate environment in order to have the most reliable view of trophic relationships between plants, animals and microbes living in the same restricted environment.
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The soil under the microscope: the optical examination of a small area of Scots pine litter * (Pinus sylvestrisL.)
Jean-François Ponge
Muséum National d’Histoire Naturelle, CNRS UMR 7179, 4 avenue du Petit-Château, 91800 Brunoy, France, E-mail:ponge@mnhn.fr
*  English translation of three papers published in French by Ponge (1984, 1985 and 1988). Some parts were rearranged for clarity but no attempt was made to update species and horizon names according to modern literature 1
INTRODUCTION................................................................................................................................. 9
Study site, sampling procedure and field observations.10...................................................................
Preparation of the material for laboratory observation.................................................................. 11
THE L1LAYER: RECENTLY FALLEN NEEDLES AND LIVING MOSS.................................12
Decaying needles....................................................................................................................5..............1
Needles without any external sign of fungal attack............................................................................... 15
Needles attacked by parasitic fungi...................................71....................................................................
Lophodermium pinastri................................................................................................................. 17
Ceuthospora pinastriandLophodermella sp................................................................................ 17
Needles attacked by the saprophyticVerticicladium trifidum .............................................................. 17
Needles attacked byVerticicladium trifidumafterLophodermium pinastriandCeuthospora pinastri 19
Conclusions about decaying needles.....................................................................................................21
Decaying twigs..................................................................................................................................... 21
Bark fragments.................................................................................................................................... 22
Living and decaying moss (Pseusceropodium purum)...................................................................... 23
Fauna.................................................................................................................................................... 23
Inventory................................................................................................................................................ 23
Enchytraeid worms........................................2..3......................................................................................
Transport on the tegument............................................................................................................. 25
Feeding activity…………………………………………………………………………………..27
Nematodes............................................................................................................................................. 27
Oribatid mites27........................................................................................................................................
Springtails............................................................................................................................................. 29
Fly larvae…………………………………………………………………………………………………………………………………..29
Animal faeces....................................................................................................................................... 29
Animal corpses.....................................................................................................................................31
Conclusions about the L1layer........................................................................................................... 31 2
THE L2LAYER: DECAYING NEEDLES AND DEAD MOSS......................................................32
Decaying pine needles......................................................................................................................... 34
Needles attacked by........................................................................................ 35Verticicladium trifidum
Needles attacked byMarasmius androsaceus………………………………………………………………………………...35
Needles attacked by unidentified fungi73..................................................................................................
Needles with bacterial development...................................................................................................... 39
Needles with bacterial and micro-algal development........................................................................... 40
Needles penetrated by enchytraeids...................................................................................................... 39
Hyphal networks embedding decaying pine needles............................................................................. 41
Conclusions about decaying pine needles............................................................................................. 44
Decaying pine twigs............................................................................................................................. 43
Decaying euphylls of pine................................................................................................................... 45
Decaying male flowers of pine............................................................................................................ 45
Decaying branchwood of pine............................................................................................................ 45
Bark....................................................................................................................................................... 46
Wood...................................................................................................................................................... 47
Pine ectomycorrhizae.......................................................................................................................... 49
Decaying moss (Pseudoscleropodium purum).................................................................................... 49
Stems...................................................................................................................................................... 49
Leaves.................................................................................................................................................... 49
Decaying bracken foliage (Pteridium aquilinum).............................................................................. 50
Leaflets.................................................................................................................................................. 50
Leaflets with limb still present ...................................................................................................... 50
Vein networks................................................................................................................................ 52
Rachises................................................................................................................................................. 52
Fauna.................................................................................................................................................... 52
Inventory................................................................................................................................................ 53
Enchytraeid worms........................................................................................................65........................
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Oribatid mites.................................................................................................06.......................................
Springtails............................................................................................................................................. 62
Fly larvae.............................................................................................................................................. 62
Nematodes............................................................................................................................................. 64
Cyst amoebae........................................................................................................................................ 64
Animal faeces....................................................................................................................................... 64
Macroinvertebrate faeces...................................................................................................................... 64
Enchytraeid faeces................................................................................................................................ 65
Oribatid faeces...................................................................................................................................... 65
Springtail faeces.................................................................................................................................... 69
Animal corpses and corpse fragments............................................................................................... 69
Conclusions about the L2layer...........17................................................................................................
THE F1LAYER: FRAGMENTED NEEDLES, INVERTEBRATE FAECES AND MYCORRHIZAE.................................................................................................................................73
Decaying pine needles......................................................................................................................... 77
Fungal mantle around pine needles...................................................................................................... 77
Inside of pine needles............................................................................................................................ 79
Needles attacked byVerticicladium trifidum, but not byCenococcum geophilum..........79.............
Needles attacked byCenococcum geophilum............................................................................... 80
Pine roots and mycorrhizae, mycorrhizal fungi............................................................................... 82
Living roots........................................................................................................................................... 82
Coralloid orange-brown ectomycorrhizae ..................................................................................... 82
Black ectomycorrhizae .................................................................................................................. 83
Pink ectomycorrhizae .................................................................................................................... 84
Long roots ..................................................................................................................................... 84
Decaying roots...................................................................................................................................... 86
Short roots ..................................................................................................................................... 86
Long roots ..................................................................................................................................... 87
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Sclerotia ofCenococcum geophilum............................................................................................. 87
Pine twigs............................................................................................................................................. 87
Preliminary remarks.............................................................................................................................. 87
Wood...................................................................................................................................................... 88
Penetration by basidiomycetes without any attack of lignified walls............................................ 88
Penetration by fungi and bacteria with soft-rot attack................................................................... 88
Bark....................................................................................................................................................... 90
Pine bark.............................................................................................................................................. 90
Notice.................................................................................................................................................... 90
Thin bark fragments.............................................................................................................................. 90
Thick bark fragments............................................19.................................................................................
Pine euphylls........................................................................................................................................ 91
Male flowers of pine............................................................................................................................ 92
Miscellaneous pine material............................................................................................................... 92
Leafy shoots of moss (Pseudoscleropodium purum).......................................................................... 93
Preliminary remarks.............................................................................................................................. 93
Leaves.................................................................................................................................................... 93
Attack of soft-rot type ................................................................................................................... 93
Attack of white-rot type ................................................................................................................ 93
Stems..93....................................................................................................................................................
Notice ............................................................................................................................................ 95
Cells with cell contents still present .............................................................................................. 95
Penetration of fungal hyphae......................................................................................................... 95
Penetration of microfauna ............................................................................................................. 95
Hollow moss stems........................................................................................................................ 96
Concluding remarks ...................................................................................................................... 96
Bracken fronds (Pteridium aquilinum).............................................................................................. 96
Bracken leaflets..................................................................................................................................... 96 5
Bacterial stage ............................................................................................................................... 98
Cenococcumstage ......................................................................................................................... 98
Rachises................................................................89.................................................................................
Birch (Betula pubescensEhrh.).......................................................................................................... 99
Leaves.................................................................................................................................................... 99
Achenes...99...............................................................................................................................................
Mucus................................................................................................................................................. 101
Preliminary remarks............................................................................................................................ 101
Fungal development............................................................................................................................ 101
Decay of the fungus............................................................................................................................. 101
Rhizomorphs...................................................................................................................................... 101
Quartz grains..................................................................................................................................... 103
Spider cocoons................................................................................................................................... 103
Colonies of Chrysophyceae (golden algae)...................................................................................... 103
Fauna.................................................................................................................................................. 103
Inventory.............................................................................................................................................. 103
Protozoa.............................................................................................................................................. 105
Rotifers................................................................................................................................................ 107
Nematodes........................................................................................................................................... 107
Enchytraeid worms..................180............................................................................................................
Preliminary remarks .................................................................................................................... 108
Generalities.................................................................................................................................. 108
Moss material .............................................................................................................................. 109
Pine tissues .................................................................................................................................. 109
Fungal material............................................................................................................................ 109
Bacteria........................................................................................................................................ 110
Thecamoeban cysts...................................................................................................................... 110
Pine pollen................................................................................................................................... 110 6
Mesofaunal faeces ....................................................................................................................... 110
Algae ........................................................................................................................................... 112
Intestinal microflora .................................................................................................................... 112
Transport on the tegument........................................................................................................... 112
Oribatid mites..................................................................................................................11....................2
Generalities.................................................................................................................................. 112
Box mites..................................................................................................................................... 114
Nothrus sylvestris........................................................................................................................ 115
Oppiidae ...................................................................................................................................... 115
Other species ............................................................................................................................... 116
Conclusions ................................................................................................................................. 116
Miscellaneous mites and spiders......................................................................................................... 116
Woodlice.............................................................................................................................................. 117
Springtails........................................................................................................................................... 117
Insect larvae........................................................................................................................................ 120
Animal corpses................................................................................................................................... 121
Preliminary remarks....................................1..21......................................................................................
Enchytraeid worms......................................................................................................212........................
Oribatid mites....................................................................................21.2.................................................
Other arthropods................................................................................................................................. 125
Animal faeces..................................................................................................................................... 125
Type A faeces (slugs?)......................................................................................................................... 125
Type B faeces (woodlice?)................................................................................................................... 126
Type C faeces (earthworms)................................................................................................................ 127
Mineral faeces..................................................................................................................................... 129
Preliminary remarks .................................................................................................................... 129
White mineral faeces ................................................................................................................... 129
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