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Professor Jim Harris School of Applied Sciences Cranfield University Bedfordshire UK
Preserving biodiversity and soil
structure and function
Talk outline
• Global challanges • Life in the soil and soil function • Effects of land use • Ecosystem service framework for monitoring and
decision support • Options for the future to maintain and enhance
soil resources • Conclusions
Challenges
• Global climate change • Sea level rise • Agricultural intensification • Food and water security • Loss of biodiversity
Ellis and Ramankutty 2008
Life in the soil/soil function
Soils are remarkably complex •Physically •Chemically •Biologically
5 cm 5 mm
HOW MUCH LIFE IS THERE ?
SOIL BIOMASS • handful of arable soil
(c. 200g) • approximately
0.5 g of fresh biomass (mainly ‘microbial’)
• Over 10,000 species per gram (conservative estimate)
5 tonnes per hectare –
equivalent to 100 sheep
grassland – 20 times greater = 2000 sheep per hectare
THE WORKING SOIL ENGINE
CARBON
THE FUEL OF
THE SOIL
ENGINE
PLANT MATERIAL SOIL ORGANIC
MATTER
MAMMALS
PROTOZOA
NEMATODES
INSECTS
ARACHNIDS
MOLLUSCS
WORMS
BACTERIA
FUNGI
FOOD WEBS:
Soil
biota C
C storage
C loss
Regulated by
•Structure
•Chemistry
•C input quality & quantity
•Community phenotype
Effects of land use on soil biodiversity, function and carbon
Organic Matter losses due to land-use
0
100
200
300
400
500
600
Forest Bare Agriculture Agroforestry
Land-use type
OM
lo
ss k
g/h
a/y
r
Redrawn from McDonald et al (2002)
Change in soil carbon in response to change in
land use (redrawn from Guo and Gifford 2002)
-80 -60 -40 -20 0 20 40 60
Overall
Pasture to plantation
Native forest to plantation
Native forest to crop
Pasture to crop
Native forest to pasture
Crop to pasture
Crop to plantation
Crop to secondary forest
Perc
en
tag
e c
han
ge
Hendrix et al 1986
Increasing susceptibility to disturbance
Cumulative perennial ryegrass yields with and without
earthworms, in organically and inorganically fertiliser regimes
Redrawn from Boyle et al (1997)
Resultant
Ecosystem
Service flow
Susceptibility
To each
Degradation
Pressure
Soil type
Lost
Services Costs Land Use
Degradation Pressures •Physical •Chemical •Biological
Actual
degradation
Benefits
Ecosystem services approach for monitoring what is going on
•Framework for assessment •Natural Capital
Land Use Change
•Deforestation
•Urbanization
•Agricultural Expansion
•Conversion to grazing
•Agricultural intensification
Ecosystem consequences
•Food, fibre, timber for human consumption
•Climate feedbacks
•Disease
•Water quantity and quality
•Biodiversity
Assessment of
trade-offs
Ecological knowledge
Societal values
Soil-dependent
ecosystem services
Critically, these are
RENEWABLE services
Options for the future to maintain and enhance soil resources
•No/min till •Land sparing •Mixed landscapes •Reserves and hydroponics
Effect of soil management on soil microbial biomass-C
(redrawn from Feng et al 2003)
0
50
100
150
200
250
Feb May October
Month
Bio
mass-C
(u
g/g
)
Conventional
No-till
Effect of soil managment on soil organic matter
0
5
10
15
20
25
30
35
40
0 to 1 1 to 3 3 to 7.6 7.5 to 15.2
Depth (cm)
Org
an
ic m
att
er
(g/k
g)
Conventional
No-till
Location of straw residues dependant on tillage type
0
10
20
30
40
50
60
70
80
90
100
0-5 5-10 10-15 15-20 20-25
Depth (cm)
Perc
en
tag
e o
f to
tal
Conventional
Reduced
No-till
Redrawn from Tebrugge and During 1999
Effect of conventional and no-till managment on
aggregate stability (redrawn from Rhoton et al
2002)
0
10
20
30
40
50
60
0 to 1 1 to 3 3 to 7.6 7.5 to 15.2
Depth (cm)
Perc
en
tag
e o
f so
il b
y w
eig
ht
Conventional
No-till
Effect of land-use on sediment losses
0 200 400 600 800 1000
Normal Ploughing
Cross-ploughing
Cultivation
Stubble tillage
Winter wheat
Winter wheat (no added P)
Buffer strip
Stubble
Direct sowing
Grass ley
mg/litreRedrawn from Puustinen et al 2004
Economic return (redrawn from Al-Kaisi and Xin 2004)
0
50
100
150
200
250
No-till Chisel-plough Ploughed
Tillage type
Eco
no
mic
retu
rn (
US
D/h
a)
Redrawn from Hodgson et al (2010) Ecol.Lett
Redrawn from Hodgson et al (2010) Ecol.Lett
Combining land-use
can lead to significant
biodiversity gains –
Butterfly abundances
in different land use
types
Conclusions
• Achieving food security and soil health is a complex issue requiring careful consideration and quantification of trade-offs
• The Ecosystem Services approach offers a sound framework to analyse options
• The options for land use require a greater understanding of our soils, and a higher resolution to make decisions resulting in sustainable landscapes.
Thank you for listening!
Potential Ecosystem Map • Digital Terrain Model • Soil Maps • Geology Maps • Climate data • Land-use data • Hydrological function • Socio-economic models • Climate change scenarios
Methodology
One model to bind them all…….
Ecosystem service map
Ecosystem service map
Ecosystem service map
Ecosystem service map
