Tree-soil-crop interactions in rubber agroforestry

1. Tree-soil-crop interactions
in rubber agroforestry
7 April 2021, 14:10 – 14.40
Meine van Noordwijk

2. until they realize
what the sealed door is like
Many claim to have the key…
1 2 4 8 16 32 64
Interdisciplinary interactions sometimes
reminds one of the old man looking for a lost
key under a streetlamp, “Did you lose your
key here?”, “No, but here I at least have light
to see anything”. We all do what we have
been trained to do – not necessarily what is
the most relevant to do.

3. Todays realization of yesterdays “options in context”  innovation Tomorrow…
Path
depen-
dency
Intellectual property rights (IPR)
Theory of
change

4. AF3: Policy-level harmonization of land use
governance across forest-agriculture continuum
AF2: Landscape level interactions
between tree cover, livelihoods
and ecosystem services
AF1: Plot-level
combination of trees,
crops and/or livestock
Multipurpose
trees in
agroforestry
landscapes
Agroforestry
… is now understood as a concept that applies at plot/farm (AF1), landscape (AF2) and gover-
nance (AF3) level; all interfacing agriculture and forestry, reflecting the origin of the term [[i]].
[i] van Noordwijk M, Coe R, Sinclair FL. 2019. Agroforestry paradigms. pp 1-14, In: van Noordwijk M (Ed.)
Sustainable Development Through Trees on Farms: Agroforestry in its Fifth Decade. World Agroforestry
(ICRAF), Bogor, Indonesia. https://www.worldagroforestry.org/trees-on-farms

5. Land
use
AF policy (rights,
incentives, moti-
vation), Goals
AF landscape
management
AF practices &
farmer choices
Tree-Soil-Crop-Livestock-
Climate interactions
1.11 Land use as inte-
grated policy agenda
Cardinael R, Cadish G, Gosme
M, Oelbermann, van
Noordwijk M. 2021. Climate
change mitigation and
adaptation in agriculture:
why agroforestry should be
part of the solution.
Agriculture, Ecosystems and
environment (**)

8. Multipurpose
trees in
agroforestry
landscapes

9. Local
Ecological
Knowledge
Modeler’s
Ecological
Knowledge
Public/Policy
Ecological
Knowledge
Based on ‘categories’,
definitions
Based on ‘processes’
(hypotheses, models)
Direct
‘observables’
includes
balance
sheets
Laws
Urban
folks
Local
govt
Social
scientists
Econo-
mists
Eco-
logists
Women
Men Lowland/
upland
Responding to ‘issue
cycles’
The diversity of Local ecological knowledge
… has triggered much of science-based exploration, but constructed a different explanatory
basis; it also interacts with public/ policy knowledge that tends to focus on categories and
definitions, demarcating rights.
van Noordwijk M, Williams S, Verbist B. 2001. Towards integrated natural resource management in forest margins of the humid tropics. ICRAF, Bogor.

10. Local
know-
ledge
Science-
based
Public/
policy
views
identity
[i] Hoang MH, Joshi L, van Noordwijk M. 2013. Participatory landscape appraisal (PaLA).
pp 16-21 in: van Noordwijk M, Lusiana B, Leimona B, Dewi S, Wulandari D (eds).
Negotiation-support toolkit for learning landscapes. (Eds.) World Agroforestry Centre
(ICRAF) Southeast Asia Regional Program. Bogor, Indonesia.

11. Forest
Jungle rubber
agroforestry
young rubber
with natural
regrowth
3-9 years
Swidden: Young
rubber with other
edible crops
up to 3 years
latex
production
10-25 years
Declining
production 25-40 years
Biomass
Tree diversity
Slash and burn
Land clearing
Gap
rejuve-
nation
“sisipan” Cyclical
Cyclical vs internal rejuvenation (‘sisipan’) agroforests reflect two types of forest manage-
ment: gap-level (underplanting) or whole-field (even-aged); if burning is not allowed, food crops
are skipped.
Joshi L, Wibawa G, Beukema
H, Williams S, van Noordwijk
M. 2000. Technological
change and biodiversity in
the rubber agroecosystem
of Sumatra. Tropical
Agroecosystem, pp.133-155.
Xu J, Yi Z. 2015. Socially
constructed rubber
plantations in the swidden
landscape of southwest
China.
Cairns M (Ed.) Shifting
Cultivation and
Environmental Change:
Indigenous People,
Agriculture and Forest
Conservation. , Routledge,
London.

12. Four origins for four modes of tree crop cultivation:
Modified
forest
Agroforest
Monocul-
ture
Simple agro-
forestry
Old-growth
forest
Swidden –
fallow cycles
Open-field
agriculture
Degraded
lands
Evolving tree crop production systems derive from four types of preceding land uses, provi-
ding multiple interpretations of ‘deforestation’ and ‘restoration’, but also influencing soil and vegetation.
[i] Martin DA, Osen K, Grass I, Hölscher D, Tscharntke T, Wurz A, Kreft H. 2020. Land‐use history determines ecosystem services
and conservation value in tropical agroforestry. Conservation Letters, 13(5), p.e12740.

13. 15
10
5
0
Number
of
tree
species
per
40
x
5
m
plot
Mono-
culture
0 0.5 0.8 1.0
X as share of total basal area
Complex X–based
agro-forestry system
Simple X–based
agroforestry system
Complex
mixed
agroforest
Agroforestry categories distinguish ‘monoculture’, simple and complex agro-forestry systems, and
complex, mixed agro-forest (the latter usually are ‘multistrata’),based on tree diversity and relative share of
the main tree in the total basal area [30, [i]] [i] Joshi L, van Noordwijk M, Martini E, Janudianto. 2013. Rapid appraisal of
agroforestry practices, systems and technology (RAFT). pp 36-42 in: van
Noordwijk M, Lusiana B, Leimona B, Dewi S, Wulandari D (eds). Negotiation-
support toolkit for learning landscapes. World Agroforestry Centre (ICRAF),
Bogor, Indonesia.

14. Wood
density,
g
cm
-3
A1
A2
B1
B2
C1
C2
D1
D2
Very light Medium Heavy Very heavy
Cumulative frequency Fraction
A1
A2
B1
B2
C1
C2
D1
D2
A. B.
Wood density
… reflects a trade-off between tree growth rate and longevity. Community-level wood density
profiles indicate the successional status and renewal within a vegetation [[i]].
[i] Rahayu et al – Wood density and dispersal modes of trees regenerating in disturbed forests and agroforests in Indonesia in review
Rubber agroforests Jambi .

15. Managing complex rubber agroforestry
systems may be surprisingly simple.
Five basic rules:
1) Use and build on what you have;
2) Harvest what you need, but leave something for tomorrow;
3) Reduce growth of species that hinder other, more valuable components;
4) Protect the plot from external disturbance, and
5) If you want, actively introduce valuable components from outside.
Use of space probably is the primary concern, but it stands for light, water
and nutrients as primary above- and belowground growth resources.
Local
know-
ledge

16. Urban, transport,
industries
Open-field
agriculture
Half-open
agroforestry
Natural forest
& analogues
Coarsening the mosaic
Specialisation, trade globalisation,
industrial intensification
Finer-grained mosaics
Diversification, agroforestation,
ecological intensification Human dominated
Nature-based
(Agro)ecosys-
tem services
Peo-
ple
peo-
ple
people
6
4
2
1 3
5
people

17. Biodiversity versus C stocks
Plot-level diversity (e.g. of trees) usually correlates with C stocks, but degradation and
restoration curves can differ [, ].
Sari RR, Saputra DD, Hairiah K, Rozendaal DMA,
Roshetko J, van Noordwijk M. 2020. Gendered
species preferences link tree diversity and carbon
stocks in cacao agroforest in Southeast Sulawesi,
Indonesia. Land 9, 108
Tscharntke T, Tylianakis JM, Rand TA, Didham RK,
Fahrig L, Batáry P, Bengtsson J, Clough Y, Crist TO,
Dormann CF, Ewers RM. 2012. Landscape
moderation of biodiversity patterns and
processes‐eight hypotheses. Biological
reviews, 87(3), pp.661-685.

18. Due to certification criteria
constraining use of yield-
enhancing inputs
Due to environmental con-
straints (~ pollution) to use
of yield-enhancing inputs
Due to inadequate/ incom-
plete control of weeds
Due to inadequate/
incomplete control of
pests & diseases
Due to nutrient deficiency
and fertilization practice
Actual
yield
Yield gap
Potential yield for the tempe-
rature, light and [CO2] of the
location
Due to water shortage
during growing season ~
irrigation
Due to sub-optimal crop
choice ~ climate
Due to lack of pollinators,
symbionts, harvesting
Due to marginal costs
(inputs) exceed benefits
(outputs)
Due to social constraints
to labour availability at
required time
As a rule of thumb, going after the last 20% of
yield gap closure may not be worthwhile.
Yield gaps … are defined as the difference between actual and potential yields, expressed in an absolute or
relative quantity
Woittiez LS, van Wijk MT, Slingerland M, van Noordwijk M, Giller KE.
2017. Yield gaps in oil palm: A quantitative review of contributing
factors. European Journal of Agronomy, 83, pp.57-77.
Agronomic vs Economic interpretation

19. Plot-to-
landscape
scale
metric for
multifunc-
tional land
use
LERM = ɣP ∑i Pi /Pi,ref + ɣR ∑j Rj /Rj,ref + ɣC ∑k Ck /Ck,ref
Societal
weighting of
provisioning
services
• Pi , Rj and Ck be the attainment (in any metric) of a range of provisioning (P),
regulating (R) and Cultural (C) services provided by a landscape
• Pi,ref ,Rj,ref and Ck,ref be the attainment (in the same metric) of such services in
a landscape optimized for that specific service (often a ‘monoculture’)
• ɣP,i , ɣR,j and ɣC,k be a weighting function for the importance of the three
groups of ecosystem services
Societal
weighting of
regulating
services
Societal
weighting of
cultural
services
Current vs
reference
services per
unit land
Current vs
reference
services per
unit land
Current vs
reference
services per
unit land
the Land Equivalent Ratio (LER) … replaces ‘yield gap’ as key metric for evaluating the land use
efficiency of mixed production systems, as it also relates actual to potential yield; however,
values above 1.0 suggests ‘negative yield gaps’. If LERM the “Land Equivalent Ratio for Multifunc-
tionality” exceeds 1.0 the integrated system spares land relative to segregated monofunctional
land uses.
[i] Khasanah N, van Noordwijk
M, Slingerland M, Sofiyudin M,
Stomph D, Migeon AF, Hairiah
K. 2020. Oil Palm Agroforestry
Can Achieve Economic and
Environmental Gains as
Indicated by Multifunctional
Land Equivalent Ratios. Front.
Sustain. Food Syst. 3: 122. doi:
10.3389/fsufs.

20. Digesting WaNuLCAS outputs for a coherent
set of performance indicators
Yields of crops and trees
(for some indicators also model
runs for monocultures)
Use of labour and inputs
Harvested products:
Yields of crop types i
Firewood
Fodder
Fruits
Timber
Attributed input use:
Fertilizer used
External organic inputs
Agrochemicals
Labour used
Irrigation water used
Meeting daily requirements of
X persons/ha, in terms of
 Calories
 Protein
 Vitamins
 Energy (wood, manure, …)
 Construction wood
Life-cycle appraisal of:
 Gross income: $ ha-1 y-1
 Returns to labour: $/day
 Net Present Value: $/ha
 Land Equivalent Ratio [] for
food/income/provisioning
Nutrient balances
Water & soil balance
C-stocks and GHG balance
Total water yield: mm y-1
Slow-flows water yield mm y-1
Time-avgd soil cover []
Net sediment yield: t ha-1 y-1
Net N leaching: kg N ha-1 y-1
Net N2O emission: g N2O-N ha-1 y-1
Net CH4 emission g CH4-C ha-1 y-1
Change in C stocks: t C ha-1 y-1
ES Land Equivalent Ratios [] for
regulating services: forest area
needed for equivalent
 Slow-flow water
 C-stocks
 Net GHG emissions
Time needed to restore
o Net soil loss
o Corg
Spreadsheet
conversion,
use
of
external
databases
Irrigation resources

22. Smallholder oil palm:
space for diversification?
http://bscmsc.pps.wur.nl/node/374

23. Key inputs to be user-defined
Core modules
Key outputs
Tree,crop,soil
properties
N and P
balance
Layer 1…4
SOM C, N, P
N and P in
layers 1…4
N & P uptake
in layers 1…4
N & P inputs,
leaching
Litter layer C,
N, P change
Spatial AF zone
settings
Carbon
balance
Tree growth&
management
Tree water
dynamics
Tree root
dynamics
Light capture
Litterfall,
organic input
Rainfall, Clim
data
Evaporation at
soil surface
Water in
layers 1…4
Water uptake
in layers 1…4
Rainfall
interception
Runoff, infil-
tration, GW
Water balance
Management
calendar
Yields,
Profitability
Crop growth,
management
Crop water
dynamics
Crop root
dynamics
Actual crop
sequence
Rule-based
management
Further
Inputs
Optional
modules
Rainfall
simulator
Hydraulic
equilibration
Lateral flows
Soil struc-
ture dynamics
Erosion &
sedimentation
Slash&burn
land clearing
N2O
emissions,
CH4 balance
Filter func-
tions
Additional
outputs
Further
inputs
Optional
modules
Grazing
Pests &
diseases
Tree
parasites
 Palm
physiology
Latex
production
Labour
accounting
Additional
outputs

24. Plot-level
Managing a
mixed-age stand
where enough
trees are
productive to
maintain positive
cash flow;
consider plot-level
diversification
Tree-level
Grafting more
productive clones
on existing stems,
maintaining root
systems and soil
Low-risk, low invest-
ment needs, not
achieving maximum
production/ha
Farm-level
Obtaining credit to
cover the
replanting costs
and the
maintenance
period until a net
positive cash flow
is attained
Plot-level
Remove existing
vegetation (with or
without burning)
and plant new
(grafted?)
seedlings;
improved planting
material & density,
inter-cropping?
Tree-level
Remove existing
vegetation (with or
without burning)
and plant new
(grafted?) seedlings
Supply-shed-level
Local supply stays (or is expected soon to
do so) behind on installed processing
capacity, making investment in
rejuvenation inevitable
High yields tar-
geted, but risks of
replant failure add
to investment
requirements
3.23 Pathways for tree-crop rejuvenation reach across scales While large-scale plantations may plan for a
rotation with replanting at the end of a cycle, paid for by current production elsewhere, smallholders generally have not been
able to save for such and are dependent on external support, often in the form of government programs and subsidized loans.
There is, however, an alternative in the mixed-age agroforestry system that are managed at tree, rather than field, level and in
which risks are manageable; top-working and in situ grafting
can be applied to coffee and various other fruit trees.
Vaast P, Harmand JM, Rapidel B, Jagoret P, Deheuvels O. 2016. Coffee and cocoa
production in Agroforestry—a climate-smart agriculture model. In Climate change
and agriculture worldwide (pp. 209-224). Springer, Dordrecht.
Internal rejuvenation, mixed-age Rotational, even-aged plantation

25. Climate change resilience…
•There is an interesting difference between rubber and oil
palm in Indonesia, in so far as the early rubber clonal
selections GT1 were developed in Getas (Salatiga, Java) a
sub-optimal climate, so the clones do invest in root
development and are fairly robust (also being used in
China for cold-tolerant rubber selections); later selections
from wetter places are more productive, but less robust.
•Oil palm, in contrast started in N. Sumatra in the most
stable climate, without dry season. Productive oil palm
is, however, very sensitive to dry periods now that it is
used elsewhere in Indonesia as well; the physiological
shift to male flowers hasn’t been selected against.

26. Rantau-pandan transition
from rubber to oil palm

27. RUBIS
No Rubish

29. Todays realization of yesterdays “options in context”  innovation Tomorrow…
Path
depen-
dency
Intellectual property rights (IPR)
Theory of
change