Stewardship
of
Soil Ecosystem Services
Howard Ferris
Department of Nematology
University of California, Davis
November, 2010
The soil ecosystem is strongly affected by type and frequency of Carbon and Energy input
CO2
carbohydrates
and
proteins
carbohydratesC
and
amino acids N
CO2
CO2
bacteria
protozoa
nematodes
nematodes
nematodes
other
arthropods
organisms
fungi
fungi
NO3
Carbon and energy transfer
CO2
arthropods
nematodes
•Carbon
is respired by all
organisms in the food web
Carbon and
NH3 •The amounts
NHof
NH3
3
Energy available limit the size
and activity of the web
Carbon and Energy
Subsidy Effects
Prey resources
800
Input Biomass
700
Predators
600
500
400
300
200
100
0
0
50
100
150
200
Time
Infrequent (Punctuated) Resource Input
250
300
350
400
Carbon and Energy
Subsidy Effects
Prey resources
800
Input Biomass
700
Predators
600
500
400
300
200
100
0
0
50
100
150
200
Time
Frequent (Continuous) Resource Input
250
300
350
400
Land-use change in Kansas
Resource Inputs:
Bottom up effects on
Soil Ecosystem Structure
and Function
Community Ecology
Structure
Index
From Glover et al., 2010
Basal
Index
•Consistent N-yield
over 75 years
without input
•N-yield similar to
that of high input
wheat
Soil Ecosystem Functions - metabolic and behavioral activities
of organisms that impact the biotic or abiotic components of the ecosystem
Feeding:
Behavior:
Ingestion, assimilation, defecation and excretion
Movement, activity, migration
Functions may be classified, subjectively, as Services, Disservices
(or Neutral)
Disservices:
Damage plants of agricultural or ornamental significance
Injure humans and vertebrate animals
Services:
Sequester and redistribute minerals
Individual species
Mineralize organic molecules
services
Accelerate turnover
Regulate and suppress pests
Alter substrate to provide access to other organisms
Redistribute organisms in space
Biodegrade toxins
Aggregate
Reduce soil erosion
Increase agricultural production
ecosystem services
Management of Soil Organisms….
to enhance services and reduce disservices
Provide Services
Provide Disservices
Management tradeoffs?
Soil Ecosystem – environmental effects on Structure
Standardized Counts
Nematode Sensitivity to Mineral Fertilizer
Ammonium sulfate
200
Nematode guild
150
c-p 1
c-p 2
c-p 3
c-p 4
X c-p 5
100 X
50
X X
0
0 0.02 0.05 0.1
X X
0.5
1
Concentration (mM-N)
Tenuta and Ferris, 2004
Some Ecosystem Functions
Feeding and Redistributing Organisms
Fungi exploit nematodes through:
1. traps and networks that remain
attached to the hyphae.
2. spores that detach from hyphae
Behavioral Ecology
Distribution of organisms to new resources
bacteria and bacterivore nematodes
0 nematodes
Bacterial Cells
100
5 nematodes
Positive feedback
Overgrazing
20 nematodes
80
60
40
20
0
0
5
10
20
40
Nematode Abundance
Fu et al. 2005
80
160
Exploiting Ecosystem Services:
The N-Mineralization Service of Bacterivore Nematodes
Taking it to the field……
Soil Ecosystem Management – an experiment
Cover crop
Cover crop
Irrigation
temperature
moisture
T0
activity
M0
Aug
Ferris et al., 2004
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Complementarity
NitrogenFunctional
mineralization
14
N- mineralization
N (µg/g Soil)
12
10
Cruznema
6 500
2
0
A diverse functional guild
of bacterivores supports….
Mesorhabditis
8 600
4
+Cephalobus
-Cephalobus
Rhabditis
400
Total N
300
200
5
100
10
15
20
25
30
35
40
45
Organic Matter C:N Ratio
29-Jul
22-Jul
15-Jul
8-Jul
1-Jul
24-Jun
17-Jun
10-Jun
3-Jun
27-May
20-May
13-May
6-May
29-Apr
22-Apr
15-Apr
8-Apr
1-Apr
0
Functional Continuity
N-mineralization
Mesorhabditis
900
800
700
600
500
400
300
200
100
0
Acrobeloides bod
Ferris et al., 2004
29-Jul
22-Jul
15-Jul
8-Jul
1-Jul
24-Jun
17-Jun
10-Jun
3-Jun
27-May
20-May
13-May
6-May
29-Apr
22-Apr
15-Apr
8-Apr
1-Apr
Total N
Another Ecosystem Service: Regulation of Opportunistic Species
Density-dependent predation
Soil Suppressiveness
100
95
90
85
80
0
0.1
0.2
Predator:
Prey Ratio
Predator:Prey
Ratio (Density
Class Averages)
Sánchez-Moreno and Ferris, 2007
0.3
Predators and prey
Target Prey
Amplifiable Prey
Generalist and
Specialist Predators
Soil Ecosystem Complexity and the
Regulation Function
Management practices in industrialized
agriculture result in:
Soil ecosystem simplification
Reduction in higher trophic levels
We tested nematode predator:prey hypotheses with data from
banana plantations in four Central American countries……….
Costa Rica, 2008
Banana Plantations - Panama
The relationships are fuzzy
because…………….
Ln Predator-Target Prey Ratio
B
0
-0.5
-1
-1.5
-2
-2.5
y=-4.97+0.852 x; R2=0.33; p<0.0001
-3
-3.5
2.8
Ferris, Pocasangre, et al., subm.
3.3
3.8
4.3
Ln Amplifiable Prey Abundance
Trophic cascades: amplifiable and target prey – the
expanded model
+
E3
Other Prey
A
Predator Nematodes
-
Other Predators
+
B
A
-
B
Protozoa
+
+
E2
B
E7
+
+
-
B
E1
Amplifiable Prey
E4
Target Prey
+
-
Microbial Biomass
E5
+
Nematophagous fungi
+
Rhizosphere bacteria
+
Organic Matter
Root Associate
Nematodes
+
E6
+
Plant Roots
Target Prey:
the ring nematode
Enhancing Amplifiable Prey
Soil Ecosystem – environmental factors affecting Structure
Environmental
heterogeneity
Separate
metacommunities?
Zones and
Gradients:
texture
structure
temperature
water
O2
CO2
NO3
NH4
minerals
Predator-prey Connectance
Organic Bananas and Cover Crop – Costa Rica
Winter cover crop – bell beans
Feeding the Amplifiable Prey
California, 2006
•Soil fertility
•Organic matter
•Food web activity
•Soil structure
•Fossil fuel reduction
•Habitat conservation
•Food web activity
•Soil structure
No-till soybeans, Brazil, 2006
Enrichment Indicators
Plant-feeding
nematodes
Rhabditidae
Panagrolaimidae
etc.
Short lifecycle
Small/ Mod. body size
High fecundity
Small eggs
Dauer stages
Wide amplitude
Opportunists
Disturbed conditions
Fungus-feeding
nematodes
Bacteria-feeding
nematodes
Protozoa-feeding
nematodes
Basal Fauna
Cephalobidae
Aphelenchidae,
etc.
Generalist predator
nematodes
Structure
Indicators
Specialist predator
nematodes
Aporcelaimidae
Nygolaimidae
etc.
Long lifecycle
Large body size
Low fecundity
Large eggs
Stress intolerant
Narrow amplitude
Undisturbed conditions
Nematodes at each trophic level
Moderate lifecycle
Small body size
Stress tolerant
Feeding adaptations
Present in all soils
Nematode Faunal Profiles and the Metabolic Footprint
Enriched
•Enrichment index
100 (w1.cp1 + w2.Fu2)
/ (w1.cp1 + w2.cp2 )
Ba1
Structured
Fu2
fungivores
bacterivores
Fu2
Basal
condition
Basal
Ba2
Ca3
Fu3
Ba3
Om4
Ca4
Fu4
Ba4
Om5
Ca5
Fu5
Ba5
omnivores
carnivores
fungivores
bacterivores
Structure trajectory
Ferris et al., 2001
•Structure Index = 100 wi.cpi / (wi.cpi + w2.cp2 ) for i = 3-5
Emergent Themes in Soil Ecosystem Stewardship:
1. Provide adequate and continuous resource supply to support
desired functions
2. Preserve favorable conditions for component systems
3. Engineer co-location or range overlap of interacting guilds
4. Assess magnitude of services based on faunal analysis and
metabolic footprints of functional components
http://plpnemweb.ucdavis.edu/nemaplex