Functions and Services of the Soil Food Web: Nematodes as Biological Indicators
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Transcript of Functions and Services of the Soil Food Web: Nematodes as Biological Indicators
Functions and Services of theSoil Food Web:
Nematodes as Biological Indicators
Howard FerrisDepartment of Nematology
University of California, Davis
February, 2008
Soil Food Web Functions - metabolic and behavioral activitiesof organisms that impact the biotic or abiotic components of the ecosystem
Feeding: Ingestion, assimilation, defecation and excretion Behavior: Movement, activity, migration
Functions may be classified, subjectively, as Services, Disservices (or Neutral)
Disservices:Damage plants of agricultural or ornamental significanceInjure humans and vertebrate animals
Services:Sequester and redistribute minerals
Mineralize organic moleculesAccelerate turnoverRegulate and suppress pests
Alter substrate to provide access to other organismsRedistribute organisms in spaceReduce soil erosionIncrease agricultural production
Individual speciesservices
Aggregatefood web services
Positive and Negative Feedback in Food Web Services
bacteria and bacterivore nematodes
with twenty nematodes
0 nematodes with five nematodes
Fu et al. 2005
0
20
40
60
80
100
0 5 10 20 40 80 160
Nematode Abundance
Bact
eria
l Cel
lsPositive feedback Overgrazing
0
20
40
60
80
100
0 5 10 20 40 80 160
Nematode Abundance
Bact
eria
l Cel
ls
0
20
40
60
80
100
0 5 10 20 40 80 160
Nematode Abundance
Bact
eria
l Cel
lsPositive feedback Overgrazing
Roots
Detritus
PhytophagousNematodes
SaprophyticFungi
Bacteria
Collembolans
Noncrypto-stigmatic Mites
CryptostigmaticMites
FungivorousNematodes
Bacteriophagous
NematodesBacteriophagous
Earthworms
Mites
Flagellates
Amoebae
PredaceousNematodes
PredaceousMites
PredaceousCollembolans
NematodeFeeding Mites
Linkages and Connectance among Functional Guilds
Nematodes at each trophic level
Soil Food Web Structure is strongly influencedby nature and frequency of Carbon and Energy Input
•Carbon is respired by all organisms in the web
•The amounts of Carbon and Energy available limit the size and activity of the web
Photograph courtesy of Dr. Jerry GloverThe Land Institute, Kansas
1
2
Soil D
ep
th
(m)
0
annual wheat
perennial intermediate wheatgrass
Bottom up effects:Resource availability
Soil Food Webs
OP
r
BF
P
OP
r
BF
P
Mineralization
Regulation
Effects of:tillagetertilizerspesticidespunctuated croppingtype and amount of organic input
Soil Food Web: Functions and Services in relation to Structure
Environmental heterogeneity
Zones andGradients:
texturestructuretemperaturewaterO2
CO2
NO3
NH4
minerals
Soil Food Webs – environmental factors affecting Structure
Separatemetacommunities?
Nematode Sensitivity to Mineral Fertilizer
Concentration (mM-N)
0 0.1 1
Sta
ndar
dize
d C
ount
s
0
50
100
150
200
X
X X X X
c-p 1 c-p 2 c-p 3 c-p 4 c-p 5 X
Ammonium sulfate
0.50.050.02
Nematode guild
Tenuta and Ferris, 2004
Soil Food Webs – environmental effects on Structure
Soil Nematodes as Bioindicators: Functional Diversity
Ingham
Ingham, R.E., J.A. Trofymow, E.R. Ingham, and D.C. Coleman. 1985. Interactions of bacteria, fungi, and their nematode grazers: Effects on nutrient cycling and plant growth. Ecological Monographs 55:119-140.
A milestone contribution:
When feeding on their prey, bacterial- and fungal-feeding nematodes excrete N that is in excess of their structural and metabolic needs.
1 2 3 4 5
enrichment stabilityopportunism structure
Colonizer-persister Series
Weighting:• should the separations between the classes be equal?
Bongers
Another milestone - calibration of ecosystem condition:
Maturity Index =
fi
ii pvMI,1
Bongers, T. 1990 The maturity index: an ecological measure of environmental disturbance based on nematode species composition. Oecologia 83: 14-19.
Issues of proportions:
• If the proportion of opportunists increases, the proportion of sensitive species decreases.
• It should be possible to increase structure without decreasing enrichment, and vice versa. The axes should be independent.
An Enrichment Experiment
cp1 Nematodes
0
10,000
20,000
30,000
40,000
50,000
RobbinsLeaves
RobbinsSoil
Hart Soil PlacervilleSoil
Not Enrich.
Enriched
cp2 Nematodes
0
2,000
4,000
6,000
8,000
10,000
RobbinsLeaves
RobbinsSoil
Hart Soil PlacervilleSoil
Not Enrich.
Enriched
Aphelenchoididae
0
2,000
4,000
6,000
8,000
10,000
RobbinsLeaves
RobbinsSoil
Hart Soil PlacervilleSoil
Not Enrich.
Enriched
Rhabditidae
05,000
10,00015,00020,00025,00030,00035,000
RobbinsLeaves
RobbinsSoil
Hart Soil PlacervilleSoil
Not Enrich.
Enriched
Panagrolaimidae
0
5,000
10,000
15,000
RobbinsLeaves
RobbinsSoil
Hart Soil PlacervilleSoil
Not Enrich.
Enriched
RhabditidaePanagrolaimidae
etc.
Short lifecycleSmall/ Mod. body sizeHigh fecunditySmall eggsDauer stagesWide amplitudeOpportunistsDisturbed conditions
AporcelaimidaeNygolaimidae
etc.
Long lifecycleLarge body sizeLow fecundityLarge eggsStress intolerantNarrow amplitudeUndisturbed conditions
Enrichment Indicators Structure Indicators
CephalobidaeAphelenchidae,
etc.
Moderate lifecycleSmall body sizeStress tolerantFeeding adaptationsPresent in all soils
Basal Fauna
Ba2
Fu2
Fu2
Ba1
Ba3
Fu3
Ca3
Ba4
Fu4
Ca4
Om4
Ba5
Fu5
Ca5
Om5
Enriched
Structured
Basal
Basalcondition
Structure trajectory
Enr
ichm
ent t
raje
ctor
y
omnivorescarnivoresfungivores
bacterivores
fungivores
bacterivores
fungivores
bacterivores
NematodeFaunal Profiles
•Enrichment index
100 (w1.cp1 + w2.Fu2)
/ (w1.cp1 + w2.cp2 )
•Structure Index = 100 wi.cpi / (wi.cpi + w2.cp2 ) for i = 3-5Ferris et al., 2001
Ba2
Fu2
Fu2
Ba1
Ba3
Fu3
Ca3
Ba4
Fu4
Ca4
Om4
Ba5
Fu5
Ca5
Om5
Enriched
Structured
Basal
Basalcondition
Structure index
Enr
ichm
ent i
ndex
•Disturbed•N-enriched•Low C:N•Bacterial•Conducive
•Maturing•N-enriched•Low C:N•Bacterial•Regulated
•Matured•Fertile•Mod. C:N•Bact./Fungal•Suppressive
•Degraded•Depleted•High C:N•Fungal•Conducive
Nematode Indicators of Soil Food Web Structure and Function
Ferris et al., 2001
0
50
100
0 50 100
Structure Index
Enr
ichm
ent I
ndex Prune
OrchardsYuba Co.
MojaveDesert
TomatoSystemsYolo Co.
Redwood Forest and
GrassMendocino
Co.
Faunal Analysis of some California Soil Systems
Model Verification….
OCT/ONT CST Association I Association II
BaNem PredNem PredM
Fu Nem PpNem AlgM
EI SI
BI CI
+
_
+
_ ORG OmnNem
OmnMFungSapM
Biological Associations in Crop Management Systems
Model Verification….
Sánchez-Moreno et al., subm.
Higher trophic levels
Organic Conventional
Tests of Ecosystem Services:The N-Mineralization Service of Bacterivore Nematodes
Effects of Bacterivore Nematodes onN-Mineralization Rates
0
2
4
6
8
10
12
14
5 10 15 20 25 30 35 40 45
Organic Matter C:N Ratio
N (
µg
/g S
oil
)
+Cephalobus-Cephalobus
Ferris, Venette and Lau, 1997
C:N = 4:1
C:N = 6:1
Sustainable Agriculture Farming Systems Project
1988-2000
Soil Food Web Management – an experiment
Aug Sep Oct Nov Dec Jan Feb Mar Apr May
Cover cropCover crop
Irrigation
temperature
moisture
activity
T0
M0
Soil Food Web Management – an experiment
Tomato Yields - 1997
0
10
20
30
40
50
60
+I+S+W +I-S+W +I-S-W -I-S+W -I-S-W
Tons
/Acr
eA A
B B B
Ferris et al. (2004)
Bacterivore Nematode Abundance
0
1000
2000
3000
4000
5000
6000
1-A
pr
8-A
pr
15-A
pr
22-A
pr
29-A
pr
6-M
ay
13-M
ay
20-M
ay
27-M
ay
3-Ju
n
10-J
un
17-J
un
24-J
un
1-Ju
l
8-Ju
l
15-J
ul
22-J
ul
29-J
ul
Mesorhabditis
Cruznema
Rhabditis
The Service - N mineralization- Functional Redundancy
0
100
200
300
400
500
600
1-A
pr
8-A
pr
15-A
pr
22-A
pr
29-A
pr
6-M
ay
13-M
ay
20-M
ay
27-M
ay
3-Ju
n
10-J
un
17-J
un
24-J
un
1-Ju
l
8-Ju
l
15-J
ul
22-J
ul
29-J
ul
Mesorhabditis
Cruznema
Rhabditis
The Service - N mineralization- Functional Complementarity
0
100
200
300
400
500
600
1-A
pr
8-A
pr
15-A
pr
22-A
pr
29-A
pr
6-M
ay
13-M
ay
20-M
ay
27-M
ay
3-Ju
n
10-J
un
17-J
un
24-J
un
1-Ju
l
8-Ju
l
15-J
ul
22-J
ul
29-J
ul
Mesorhabditis
Cruznema
Rhabditis
Total N
The Importance of Diversity
Mesorhabditis and Acrobeloides Abundance
0
1000
2000
3000
4000
5000
6000
1-A
pr
8-A
pr
15-A
pr
22-A
pr
29-A
pr
6-M
ay
13-M
ay
20-M
ay
27-M
ay
3-Ju
n
10-J
un
17-J
un
24-J
un
1-Ju
l
8-Ju
l
15-J
ul
22-J
ul
29-J
ul
Mesorhabditis
Acrobeloides bod
The Service - N mineralization- Functional Continuity
0100200300400500600700800900
1-A
pr
8-A
pr
15-A
pr
22-A
pr
29-A
pr
6-M
ay
13-M
ay
20-M
ay
27-M
ay
3-Ju
n
10-J
un
17-J
un
24-J
un
1-Ju
l
8-Ju
l
15-J
ul
22-J
ul
29-J
ul
Mesorhabditis
Acrobeloides bod
Total N
The Importance of Diversity
Another Ecosystem Service:
• The regulation of opportunistic species
Woodland Vineyard 0 50 100
Structure Index
0
50
100
En
rich
men
t In
dex
Density-dependent predation
80
85
90
95
100
0 0.1 0.2 0.3
Predator:Prey Ratio (Density Class Averages)
So
il S
up
pre
ss
ive
ne
ss
Predator: Prey Ratio
Sánchez-Moreno et al., in press
Managing Input Resources for Food Web Structure and Function: Carbon Pathways and Pools
Omnivory
Decomposition
Herbivory
Bacterial
Fungal
(plant source)
(detritus and exudates)
%fungal
%bacterial%plantOP
r
BF
P
Structure of the Soil Food Web in relation to Resource Inputs
Intake Channel Analysis
% Herbivore
% Fungivore
% Bacteriivore
% Herbivore
% Fungivore
% Bacteriivore
Resource Inputs: Indices are based on proportionsWhat about biomass?
Intake Channel Analysis
Some soil organisms are Herbivores
Herbivory may be a Disservice
1. It provides resources to the soil food web, often without measurable plant damage, e.g., Tylenchidae
2. It may place weed species at a competitive disadvantage
Fiddleneck and Anguina amsinckiaeSilverleaf nightshade and Ditylenchus phyllobia
(but it is difficult to find convincing examples)
Or Herbivory may provide Services
% Herbivore
% Fungivore
% Bacteriivore
Higher trophic levels- food web shape
Intake Channel Analysis
% Herbivore
% Fungivore
% Bacteriivore
Higher trophic levels- food web shape
Intake Channel Analysis
Plant Materials - Surface
0
20
40
60
80
100
0 300 600 900 1200
DD>10
Enric
hmen
t Ind
ex
C:N High
C:N Low
Control
A
C supplied
Resourcetransformation
Community structureshifts
Ferris and Matute (2003)
Resource Inputs: Transformation and Succession
Plant Low C:N
0
20
40
60
80
100
0 300 600 900 1200
DD>10 C
Ch
an
ne
l In
de
x
Cont. Undist.
Cont. Incorp.
Pl. Incorp.
Pl. Undist.
0
20
40
60
80
100
0 300 600 900 1200
A
0
100
200
300
400
500
600
700
800
0 50 100 150 200 250 300 350 400
Time
Inp
ut
Bio
mas
s
Infrequent (Punctuated) Resource Input
0
100
200
300
400
500
600
700
800
0 50 100 150 200 250 300 350 400
Time
Inp
ut
Bio
mas
s
Frequent (Continuous) Resource Input
An Experiment on Continuous Resource Input:
Soil Food Webs and Carbon Dynamics in Response to Conservation Tillage in Legume Rotations in California
So…. Inoculate nematodes into the vacant niche….
Minoshima et al. (2007)
Observation: The Structure Index did not increase in two years of
organic, no-till, continuous cropping.
Conclusion:Increase in the Structure Index after changes in management may
involve a prolonged period of recolonization by sensitive species,
that requires many years.
Continuous input but without diversity;disrupted by pesticides and mineral fertilizersContinuous input with enormousdiversity;not chemically or physically disrupted
• Occupy key positions in soil food webs• Standard extraction procedures• Identification based on morphology• Clear relationship between structure and function• The most abundant of the metazoa • Each sample has high intrinsic information value
Nematodes are useful bioindicators ofthe structure and function of the soil ecosystem
But we have
more to
learn about m
anagement of
higher trophic
levels
in the S
oil Food W
eb
•Bongers, T., M. Bongers. 1998. Functional diversity of nematodes. Appl. Soil Ecol. 10, 239-251.
•Bongers, T., H. Ferris. 1999. Nematode community structure as a bioindicator in environmental monitoring. Trends Ecol. Evol. 14, 224-228.
•Ferris, H., T. Bongers, R.G.M. de Goede. 2001. A framework for soil food web diagnostics: extension of the nematode faunal analysis concept. Appl. Soil Ecol. 18, 13-29.
•Ferris, H., M.M. Matute. 2003. Structural and functional succession in the nematode fauna of a soil food web. Appl. Soil Ecol. 23:93-110.
•Tenuta, M., H. Ferris. 2004. Relationship between nematode life-history classification and sensitivity to stressors: ionic and osmotic effects of nitrogenous solutions. J. Nematol. 36:85-94.
•Ferris, H. and T. Bongers. 2006. Nematode indicators of organic enrichment. J. Nematol. 38:3-12.
•Sánchez-Moreno, S., H. Minoshima, H. Ferris and L.E. Jackson. 2006. Linking soil properties and nematode community composition: effects of soil management on soil food webs. Nematology 8:703-715.
•Sánchez-Moreno, S. and H. Ferris. 2007. Suppressive service of the soil food web: Effects of environmental management. Agric. Ecosyst. Environ. 119:75-87.
Some Literature
More information: http://plpnemweb.ucdavis.edu/nemaplex