Landscape modeling efforts

rucksackbulgeAI and Robotics

Dec 1, 2013 (3 years and 6 months ago)

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1

Landscape modeling efforts

for N
-
Biocomplexity program

Amit Chakraborty

&

Bai
-
Lian Li


University of California, Riverside

2

S
PATIAL
T
RANSITION
M
ODEL
O
F
V
EGETATION
C
HANGES

Spatial dynamics

Temporal dynamics

Spatial interactions between

individual plants

Resource supply and transport

3

Habin Li and F. Reynolds (1997) Scale in Remote sensing and GIS. p.211
-
230

4


C
ELLULAR
A
UTOMATON

W

G

W

S


W

S


G

G

either G or W or S

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Rules of Automaton

MECHANISMS OR PROCESSES

Automaton without interference

Automaton under species invasion

Automaton after fire
-
disturbance

AUTOMATON

Resource
-
mediated competition

Resource
-
based invasion mechanism

Fire
-
induced successional processes

6

Resource
-
mediated Indirect Competition

Huston M.A. and DeAngelis D.L. (1994) Competition and coexistence: the effects

of resource transport and supply. The American Naturalist 144: 954
-
977

(k)

7

Huston M.A. and DeAngelis D.L. (1994) Competition and coexistence: the effects

of resource transport and supply. The American Naturalist 144: 954
-
977

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Resource
-
mediated direct competition

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C
1
>C
2

Schematic diagram of resource uptake mechanism from
overlapping depletion zone

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Low rate of resource input

Constant transport rate

Low rate of resource input

Competitive equilibrium

Overlapping depletion zone

Non
-
overlapping depletion zone

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Which plant will occupy the overlapping zone?

The plant has lowest resource concentration in its non
-
overlapping

depletion zone will occupy an overlapping zone at equilibrium by

depleting the resource concentration to its lowest.

What plant trait confers the competitive superiority?



1.
Higher resource capture efficiency; defined by a ratio of resource concentration

in rooting zone per unit volume and resource uptake from rooting zone per unit

volume.


2. Lower resource concentration in non
-
overlapping rooting zone


3. Less access to overlapping zone within the neighborhood of interactions.


Above three are the measure of competitive superiority and

it confers the variation of R* at equilibrium

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Overlapping

depletion

zone

Overlapping

depletion

zone

Overlapping

depletion

zone

Overlapping

depletion

zone

Overlapping

depletion

zone


Higher resource capture efficiency


lower resource concentration in non
-
overlapping rooting zone


Less access to overlapping zone within the neighborhood of interactions

Non
-
overlapping

depletion zone

Non
-
overlapping

depletion zone

Non
-
overlapping

depletion zone

Non
-
overlapping

depletion zone

Non
-
overlapping

depletion zone

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Resource
-
based invasion
mechanism


Invasive

plant trait


Native

plant trait

Lower

threshold

Upper

threshold

Range of variation of resource input rate

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S

P

A

T

I

A

L


A

B

U

N

D

A

N

C

E

S

Lower threshold

Upper threshold

Resource input rate

15

Relative physiological characters of
an invasive species

1. Higher maximal seeds production

2. Lower resource requirement for seeds production

3. Lower mortality rate

The invasive species is not necessarily to be a best resource competitor

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Limit to coexisting plant species

Spatially homogenous competitive environment is one in which

species’ competitive ranking do not change within the spatial

extent of the landscape being considered


In this environment species spatially coexist because of competition
-

colonization trade
-
off; an appropriate species trait allows spatial coexistence

of several plant species.


The resource input rate defines the limit to the number of that coexisting

plant species.


A deterministic formula calculate that number; following

parameter values are required :

a)
resource input rate b) resource transport rate c) habitat

resource concentration d) resource requirement of individual species

e) maximal rate of seeds production f) resource concentration at which the

seeds production is half the maximum

17

Fire
-
induced successional processes

Highest level: general causes of succession

Intermediate level: Contributing processes
or conditions

Site availability

Differential species availability

Differential species performance

Fire
-
disturbance

Seeds pool

Germination, establishment


Stochastic environmental stress

Competition

Lower level: Defining factors

Resource level

Temperature

Site history

Colonization

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Effects of fire and definition of resource
-
based neighborhood

Post
-
fire
habitat

Pre
-
fire
habitat

Burned

area

Burn nbd.

Semi
-
burn

nbd.

unburn

nbd.

The site specific neighborhood center at ‘x’ is defined as a physical space in which resource level is constant.


x

x


Burn neighborhood

centered at ‘x’’ is completely empty.



Semi
-
burn neighborhood

centered at ‘x’’ consists of some occupied sites and some empty sites and the center ‘x’ is
empty.




Unburn neighborhood

centered at ‘x’’ does not contain any fire affected sites and have an individual occupy the center
‘x’

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Agents:

Burn agent

Semi
-
burn agent

Unburn agent

x

x

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Simulation scheme


Temperature

Seeds pool

before fire

Colonization

Germination

Establishment

Competition
-
colonization tradeoff

R*
-
rule

Species ranking based

on time of germination

Post
-
fire
vegetation pattern

Early Succession

Late Succession

Semi
-

burn

Agent

Unburn
-

Agent

Burn
-

Agent

Germination

Establishment

Individual
-
based

model with Moore’s
neighborhood where state
transition calculated by
discrete
-
time Markov chain

Natural vegetation
dynamics

Colonization rate

Resource
utilization

rate

Temperature

Available seeds
pool

Species rank based on
resource requirement

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Simulation Steps…

Step
-
1:Classify post
-
fire habitat based on the definition of site
-
specific neighborhood


Step
-
2: Creating three agents corresponding three different nbd.


Step
-
3: The ‘burn agent’ locates all burn neighborhoods and the
‘semi
-
burn agent’ locates all semi
-
burn neighborhoods in the post
-
fire habitat.



The ‘burn agent’ and ‘semi
-
burn agent’ act till the early
successional individual at target
-
cell is replaced by late
successional individual.


Step
-
4: The ‘unburn agent’ controls natural vegetation dynamics in
the portion of the habitat which is not fire affected.



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Information needed

Spatial

Non
-
spatial

Habitat information

Total number of species

in the habitat. It depends

on pre
-
fire habitat history
.

Life
-
span of each species
.

Colonization rate of each species
.

Life
-
time N
-
consumption of each species

Post
-
fire soil temperature

Post
-
fire N level

Pre
-
fire vegetation pattern

Post
-
fire vegetation pattern

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Advantages……

1.
The model includes post
-
fire successional processes, i.e. process
based.


2.

The model is relatively simple and easy to run because less
number of data are needed to get series of vegetation patterns
correspond to different successional stages.


3.

The model has predictable potentiality.


4.

The model could be used to determine grassland or shrubland


conditions by defining successional indices.

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Thanks