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Forest Soils & Site Productivity
Soil Organic Matter and
Organisms
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ESRM 410: Forest Soils and Site Productivity The Role of Soil Invertebrates
(some of the following slides contributed by J Marra-WA Dept of Agric)
(Far Side creator-Gary Larson)2
Heterotrophic Respiration(Energy Flow)
Deciduous Forest
Net Primary
Production
Decomposers95%
Herbivores5%
Invertebrates10%
MicrobesBacteria & Fungi
90%
(Richle 1981)
(Chemoheterotrophs)
Now much research is focused on regulation of nutrient cycling
as well as ‘energy flows’ thus revealing organism/environment interaction! 3
Site and SoilSoil ProductivityProductivity
Comminution - increases surface to volume ratios of litter
Innoculation - transport microbial propagules to new substrates
Grazing - pruning response increases fungal metabolism- releases nutrients contained in microbial
biomass- alters competitive interactions and species
compositionMutualism - coevolved interaction in which both microbes
and invertebrates benefit
Microbial / Invertebrate Interactions in Soil
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Protozoa
Nematodes or roundworms
Major groups of Soil Fauna
The Microfauna < 0.1 mm
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Major groups of Soil Fauna
The Mesofauna 0.1 - 2 mm
Diplura
Featherwing beetle
Springtails
Mites
Protura Pseudoscorpions
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Major groups of Soil FaunaThe Macrofauna > 2 mm
Ants
Ground beetles
Millipedes
Earthworms
TermitesIsopods
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The Earthmovers!!
Ants
Termites
Earthworms
Invertebrate Effects on Soil Productivity
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Earthworms
- earthworms + earthworms
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Termite moundFungus farming Termitidae
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Distance NPP Infiltration rate Moisture Bulk Densityto mound (m) (g m-2 yr-1) (cm h-1) (%) (g cm-3)
1-3 728 12.0 29.2 1.2826-28 280 8.0 20.5 1.39
Productivity and soil properties in relation to distance to termite mounds.
(Arshad 1982)
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Leaf Cutter Ants: Atta sp. 13
Leaf-cutter Ant Trail
Photos by Bob Gara
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Leaf cutter AntDefoliation of Pine
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Excavated fungus garden
Vertical distribution of colony 16
NorthCarolina Puerto Rico
Costa Rica
Litterbag StudyComparison of Tropical and Temperate Forests(Heneghan et al. 2000)
NaphthaleneUntreated
P
erce
nt m
ass
rem
aini
ng
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C - without invertebrates F - with invertebrates
stems
roots in mineral soil
roots in humus
leaves
Birch Seedling Growth (Setala and Huhta1991)
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► regulating decomposition and nutrient mineralization processes
► stimulate the activity of microbial organisms, ► altering physical properties such as soil structure
and porosity ► increase moisture holding capacity of soil.
Their effects are generally greater in tropical ecosystems than temperate because of the more moderate climate.
Their effects are generally greater in deciduous forests than coniferous because of higher substrate quality.
Invertebrates contribute to soil productivity by:
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Effects of insects and diseases on forest
productivity
Good or bad?
(some of the following slides from Bob Edmonds)20
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Mountain pine beetle attacks of lodgepole pine in BC. These pictures were taken east of Quesnel about 25 miles last summer (2005). 22
The current host list includes: California black oak, coast live oak, Shreve oak,tanoak, rhododendron,California bay laurel, big leaf maple, madrone, manzanita, huckleberry, California honeysuckle, toyon,California buckeye, California coffeeberry,Douglas-fir and coast redwoodand Arrow wood (in Germany, the United Kingdom, and the Netherlands).
SUDDEN OAK DEATH An introduced disease? caused by Phytophthora ramorum
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Note height growth reduction in infected Douglas-fir trees over14 year period. Trees were age 24 at beginning of study
MeanCumulativeHeight Growth(inches)
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Impact of diseases and insects – good or bad
a. Mortality
b. Reduced growth
c. Destruction of merchantable wood (decay)
d. Reduction in pulp yield
e. Reduced wood quality - stain
f. Delayed regeneration; inadequate stocking (trees/acre)
g. Site deterioration - build up of pathogens
h. Changes in species succession
i. Creation of biodiversity
j. Decomposition and nutrient cycling27
• We know that land management practices change the soil community. The link between specific changes and soil function is less clear.
• Logging and Farming can reduce organic matter in the soil Reducing tillage tends to result in increased growth of fungi,
including mycorrhizal fungi. Decrease in OM may decrease nutrients, CEC, porosity and
water infiltration, ???
• Fire may also decrease OM, affect soil organisms, etc (direct, indirect, long & short term)
Management affects soil organisms
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• Soil biological crusts are very sensitive to trampling.
• Biosolids – OM, nutrients, water, …
• Soil compaction, lack of vegetation, or lack of plant litter covering the soil surface tends to reduce the number of soil arthropods, fungi, bacteria, etc as well as affecting root growth, aeration and water infiltration (EROSION!).
Management affects soil organisms
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Site and SoilSoil ProductivityProductivity
Physical and Chemical Properties Biological Properties
• soil organic matter• soil moisture balance• soil structure and porosity• nutrient availability• soil volume• microclimates
• mycorrhizas• nitrogen fixation• microbial decomposition• invertebrate regulation
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• A well managed soil is a
Good SoilGood Soil
• A GOOD SOIL is a
LIVE SOILLIVE SOIL
• A LIVE SOIL is a Resilient SoilResilient Soil 31