Land Use

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Land Use Land Cover Change

• CLIM 714
• Paul Dirmeyer

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LUCC - Land-Use and Land-Cover Change

• LUCC is a program element of both the
  International Geosphere-Biosphere Programme
  (IGBP) and the International Human Dimensions
  Program on Global Environmental Change (IHDP)
  with 3 foci
• FOCUS 1 Land-Use Dynamics - Comparative Case
  Study Analysis
• FOCUS 2 Land-Cover Dynamics - Direct Observation
  and Diagnostic Models
• FOCUS 3 Regional and Global Models - Framework
  for Integrative Assessments

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Disturbance Regimes

• Fire enhancement
• Fire suppression
• Increased erosion
• Decreased erosion
• Increased biotic disturbance
• Change in consequences of disturbance
• Change in susceptibility to physical forces

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Changes in processes cause many additional
changes.
e.g., changes in the hydrology of the everglades
favors some species and hurts others - leading to
a change in vegetative structure (in addition to
water regimes).
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Ecological Scaling
1 cm
1000 km
1 km
10 m
1 m
Scale is the spatial and temporal frequency of a
process or structure. A scale domain is bounded
by the grain size of processes detected and the
extent or span of processes attended.
10000 yrs
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1000 yrs
3
century
2
1
decade
Log Time (years)
year
0
month
-1
-2
day
-3
hour
-4
4
2
0
- 2
- 4
- 6
Log Space (km)
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Vegetative Scales
Forest is patterned across a range of
scales. Larger slower structures usually
constrain the behavior of faster smaller
scales. Occasionally change at a small and fast
scale spreads up to a larger scale.
1 cm
1000 km
1 km
10 km
100 m
1 m
10 000 yrs
4
region
1 000 yrs
3
forest
century
2
stand
patch
LOG TIME - years
1
decade
crown
year
0
needle/leaf
month
-1
-2
day
-3
hour
-4
4
2
0
- 2
- 4
- 6
LOG SPACE- km
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Atmospheric Processes
1 cm
1000 km
1 km
10 km
100 m
1 m
Atmospheric processes occur faster than
vegetative processes occurring at the same
spatial scale.
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region
1 000 yrs
3
forest
century
2
climate change
stand
patch
1
decade
LOG TIME - years
crown
El Niño
year
0
needle
month
-1
long waves
-2
Vegetative Structures
day
fronts
Atmospheric Processes
-3
hour
thunderstorms
-4
4
2
0
- 2
- 4
- 6
LOG SPACE- km
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Mesoscale Processes
1 cm
1000 km
1 km
10 km
100 m
1 m
10 000 yrs
4
Mesoscale disturbance processes such as fire and
spruce budworm outbreaks link the atmospheric
processes and vegetative structures.
1 000 yrs
3
Disease/pest Outbreaks
century
2
1
decade
LOG TIME - years
year
0
Fire
month
-1
-2
day
-3
hour
-4
4
2
0
- 2
- 4
- 6
LOG SPACE- km
Atmospheric Processes
Mesoscale Processes
Vegetative Structures
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Anthropogenic Processes
1 cm
1000 km
1 km
10 km
100 m
1 m
10 000 yrs
4
Anthropogenic disturbance processes such as
agriculture, logging, grazing and urbanization
can impact vegetation more broadly and quickly
than natural causes.
1 000 yrs
3
century
2
Land use changes
1
decade
LOG TIME - years
year
0
month
-1
-2
day
-3
hour
-4
4
2
0
- 2
- 4
- 6
Anthropogenic Processes
LOG SPACE- km
Atmospheric Processes
Mesoscale Processes
Vegetative Structures
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The Spread of Agriculture
Global Crop Cover Change1700 to 1992
Fraction of Grid Cell in Croplands
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300 Years of Land Use Change
Global Land Cover Types 1700 to 1992
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Estimated changes in land use from 1700 to 1995
Goldewijk K and Battjes J.J., 1997
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Night-time data from the Defense Meteorological
Satellite Program (DMSP) Operational Linescan
System (OLS)
Ecological footprint of cities
Point Area of urban-industrial infrastructure
remains small relative to other land-use/cover
changes, but its footprint has significant
land implications.
Elvidge et al., 1997
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Estimate of changes in annual NPP 1982-2000
Global monitoring can be performed by satellite,
if great care is taken to calibrate and validate
retrievals.
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Cross-calibration Across Satellites

• Long-term changes occur over periods much longer
  than the lives of individual satellites.
• Instrument drift (e.g., calibration, zenith
  crossing times) and cross-platform differences
  (e.g. different wavebands, look angles) can
  complicate long-term monitoring.

The changes in the equatorial acquisition time of
the NOAA satellite platforms
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Changes in agriculture reflected as NPP changes
evident from satellite
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Urban expansion into prime agricultural land
(China)
Landsat 198896
(K. Seto, Boston U.)
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Land use change in northern Delaware
1984
1992
Notice not only the spread of urbanization, but
also the loss of wetlands, and the shift of
agriculture to consume forest areas as cities
spread into farmland.
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Mid-Latitude Case Study Aral Sea
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Aral Sea Background Info

• Was once the fourth largest lake on the planet
• Supported an ecosystem of plants and wildlife as
  well as a habitat for humans
• Causes of decline
• 1960- Water Transfer Project begun
• Diverted large amounts of irrigation water from
  Amu Darya and Syr Darya
• Worlds longest irrigation canal (800 miles)
• Water supplied for regions crops production
  cotton, vegetables, fruit, and rice
• Water diversion combined with frequent droughts
• Consequences
• Ecological, economic, and health disasters
• 1995- ¾ water volume lost, surface area shrank by
  ½
• Salinity has tripled
• 100 million tons of salty dust dispersed outward
  up to 190 miles away
• Pollution of air, drinking water, and soil
• 2 million ha of fertile land removed from
  agricultural processes
• Amu Darya and Syr Darya are now mere trickles
• Former lake bottom is now a human made salt
  dessert

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Aral Sea Background Info Cont.

• Climate Changes
• Longer, colder winters
• Shorter, drier summers
• Growing season shortened to 170 days
• Precipitation decreased 10x along shore regions
• Salt rain
• Effects of Salt
• Kills crops, trees, and wildlife
• Destroys pasture lands
• Cotton and crop yields have declined
  dramatically
• Fishing industry devastated (twenty of
  twenty-four native species extinct)
• Roughly ½ of areas bird and mammal species gone
• Complicating Factors
• To raise yields, farmers increase use of
  herbicides, insecticides, fertilizers
• Many of the chemicals have accumulated in the
  ground water
• Low river flows have concentrated salts,
  pesticides, toxic chemicals.
• Surface water unfit to drink

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Aral Sea Landsat Images
1977 1984
1989 1995
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Aral Sea Landsat Images
1964 1973
1987
1997
1999
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Images of the Aral Sea
Former fishing village now enveloped in saline
sand
Stranded fishing boat currently miles from the
nearest water.
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Groundwater Pumping
1942
Not only surface water diversion leads to
desertification. Pumping of groundwater to
supply the city of Tucson, Arizona has lowered
the water table over 60m in some locations,
causing creeks to run dry, and riparian
vegetation to die out, greatly reducing local
evapotranspiration.
today
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Subsidence

• Venice is not the only city sinking into the sea.
  Houston is subsiding due to groundwater, gas and
  oil pumping.

1906-1995
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Deforestation
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Some facts about deforestation

• More than 8 million km2 of forest (all latitudes)
  have been cleared globally, about half of it in
  this century alone.
• Half of the world's population live in less
  developed countries in the tropics (between 23N
  and 23S), where deforestation is occurring the
  fastest.
• Tropical forests are being lost at a rate of 2-3
  per year.
• 10 of global terrestrial net primary production
  (vegetative growth) occurs in the Amazon Basin
  alone.

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Tropical Case Study Deforestation in Rondonia,
Brazil

• Background Information

• In the 1970s and 1980s landless peasants rushed
  into the rain forest under Brazilian government's
  law which declared ownership to anyone who
  cleared the land and put it to effective use.
  Using slash and burn methods they quickly
  destroy forests.
• Land was unsuitable for farming (most tropical
  soils are too poor), so peasants would have to
  move and clear new land every 2-4 years to
  continue subsistence farming.
• Ranchers moved in to claim the abandoned farms
  for grazing, consolidating small farms into large
  tracts with additional burning. Reburning every
  4-5 years is necessary to keep the land clear of
  woody vegetation that would choke out grasses.
• 23 of the 28 largest landowners in Brazil have
  their immense estates in the Amazon region
  covering more than 60 million acres.

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Rondonia, BrazilSlash Burn
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Slash-and-burn clearing of rainforest. Erosion
is also enhanced (background)
Forest converted to rangeland grasses
maintained by periodic burning
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1986
1975
1992
Landsat TM imagery over Rondonia showing
progressive deforestation along roads in
fishbone pattern
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The major cities of Brazil, Uruguay, Paraguay and
Argentina are downwind of the Amazon
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Southeast Asia Forest cover 1973
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Southeast Asia Forest cover 1985
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FAO Global Forest Resources Assessment
2000(FRA2000) Central Africa
Country Total Forest 1990 ( of total land area) Total Forest 2000 ( of total land area) Forest Cover Change 1990 2000 ( annual rate)
       
Dem. Rep. Congo 62 60 - 0.4
Congo 65 65 - 0.1
Cameroon 56 51 - 0.9
Benin 30 24 - 2.3
Ivory Coast 31 22 - 3.1
Guinea 30 28 - 0.5
       
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Scenarios of Land Cover Change
Central Africa Land Cover Change 1960-2050
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Forest-Cover Change
200 100
Amount/ Change
200 m ha lost in LDC 10
47 global loss forest cover past 8000 yrs
25 of land surface remains in forest
75 50 25
55 of forest in LDC
20 m ha gained in DW
Loss/Gain Ha 1980-95
Angelsen, in press WRI 1998 FAO 1999
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Deforestation and (sub)urbanization in the
developed world as well.
Copper Mountain, Colorado Ikonos False Color
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Long-term land-cover change in the Belgian
Ardennes
Petit and Lambin, Int. J. GIS, 2001
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Long-term land-cover change in the Belgian
Ardennes
Petit and Lambin, Int. J. GIS, 2001
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Tropical Deforestation Climate
Near the Equator, the linear, steady-state
low-level anomalous flow in response to an
anomalous heat source Q can be described by u
zonal wind component v meridional wind
component p surface pressure f Coriolis
force e damping term (friction) (Gill 1980) Q
may come from either an anomaly in the atmosphere
(e.g. precipitation anomaly), or from an anomaly
at the surface (e.g. surface temperature). Defores
tation changes the surface conditions, altering
surface heating, which can affect the overlying
atmospheric circulation, inducing further
anomalies there.
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Simple Model of Deforestation

• Most simply, heating in the tropical atmosphere
  might be changed by perturbations in
  precipitation and surface temperature
• (Eltahir and Bras 1993)
• P precipitation anomaly
• TS surface temperature anomaly
• Deforestation induces counteracting mechanisms
  that affect these quantities
• The net effect will depend on the magnitude of
  each of the individual effects. These are often
  not easy to measure or predict.

Change Decreased roughness Increased
albedo Decreased evaporation

• Affect on TS
• ?
• ?
• ?

b
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Linear estimation of deforestation impacts
bT
aP
aPbT
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Albedo Deforestation

• Deforestation with an albedo rainforest (D0)
  6 lighter (D6) and 9 lighter (D9).
• Dark grassland ? net increase in rainfall.
• Light grassland ? net decrease.
• Pattern of rainfall change is consistent.

Dirmeyer Shukla (1994 JGR)
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Tanajura et al. (2000) regional model of
deforestation
Variation among ensemble members like that for
weather and climate prediction remember
observations are effectively one ensemble member!
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Tanajura et al. (2000) regional model of
deforestation
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Tanajura et al. (2000)
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Some Desertification Statistics
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Monsoon region sensitivity

• Sensitivity experiments of desertification show
  that monsoon regions are most sensitive to
  impacts of land use/cover change

Dirmeyer Shukla (1996 QJRMS)
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Rainfall Impacts

• The largest impacts are in the monsoon regions of
  Africa (Sahel and South Africa).
• Second are the land-sea monsoons of South Asia,
  Australia and North America.
• Tropical rainfall intensifies to offset the loss
  in the subtropics.

Dirmeyer Shukla (1996 QJRMS)
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Rainfall Impacts 2

• Impacts over Africa are year-round.
• Asia, Australia, S. America have rainfall
  decreases during summer only.
• North America shows an increase in rainfall.

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Sahel Desertification

• Observed patterns of precipitation change were
  modeled in a GCM by changing regional vegetation
  to reflect desertification (Xue and Shukla, 1993
  J. Climate).
• Did overgrazing cause climate change? Did climate
  variability cause desertification? Feedbacks???

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Land Cover Change and Subtropical Climate

• Are observed rainfall trends (10 in 80 years)
  due to large-scale land use change? (Pielke et al
  1999 Marshall et al. 2004)

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Changes in Florida Land Use

• Agriculture and urbanization are the main
  influences on LUCC in this region Large losses
  of forest and wetlands (Everglades).

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Regional Modeling of LUCC Impacts

• Model suggests 12 decrease/100 years,
  commensurate with observations but what else
  has changed?

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Modeling the human element
Geist Lambin, 2002
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Merging our Physical Models with Economic,
Policy and Decision Support Models the Next
Frontier
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Historical Climate Change in the Mediterranean
Basin the Role of Vegetation Feedbacks
The Motivation Northern Africa in Roman Times was
considered one of the most prosperous and rich
areas of the western world. The production of
wheat, olive oil, and wine was greater than in
Mediterranean Europe. Strabo (I century C.E.) and
other classical authors describe northern Africa
as a strip of vegetated land, and place the
northern border of the desert a several hundred
kilometers to the south of the sea. In present
times, most of the coastal regions of northern
Africa are sub-desert or desert. Pliny (I century
C.E.) speaks of elephants living to the south of
the Atlas range, in an area that is now desert
Ptolemy (II century C.E.) describes summer
thunderstorms in Alexandria, where now summers
are dry. Archeology confirms the presence of
heavy agricultural activity in areas which are
now classified as hyper-arid. Modern palynology
has provided evidence of a trend towards drier
conditions throughout the entire Mediterranean
region.
In the numerical experiment, modern vegetation
was replaced by forests and grasslands in the
hatched areas, consistent with evidence from the
Roman Classical Period (ca. 2000 y.b.p.)
Reale Dirmeyer Reale Shukla, (2000 Glob.
Planet. Change)
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Historical Climate Change in the Mediterranean
Basin the Role of Vegetation Feedbacks
The model experiment A sensitivity test with a
low-resolution general circulation model reveals
that the position of the Inter-Tropical
Convergence Zone (ITCZ) is sensitive to changes
in surface properties far to the north, around
the Mediterranean region (Reale and Dirmeyer,
Glob. Plan. Ch. 2000). Reale and Shukla, (Glob.
Plan. Change, 2000) quantify the response of a
climate model with respect to the land surface
conditions of two millennia ago. These are
inferred mostly from palynological studies. The
experiments indicate a change in the general
circulation of the atmosphere namely a northward
shift of the ITCZ over eastern Africa, and a
land-sea circulation similar to a small-scale
monsoon occurring between the Atlas range and the
Mediterranean. These changes benefit, with a
significant increase in precipitation, the Nile
Valley and the Atlas range, which were two of the
most agriculturally productive regions of the
Roman world. Thus, the experiment suggests that
the large-scale clearings that occurred in the
Late Antiquity and during the Middle Ages, may
have contributed to the dryness of the present
climate.
Simulated summer rainfall is substantially
greater over the Nile Valley and in the vicinity
of the Atlas Mountains when modern vegetation
distributions are replaced by the vegetation of
the Roman Classical Period.
Reale Dirmeyer Reale Shukla, (2000 Glob.
Planet. Change)
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So When Did LUCC Impacts Start?

• Recent work by Ruddiman (2003) suggest that it
  may have been some 8000ybp.

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When did LUCC Impacts Start?

• Ruddiman suggests that human activities started
  increasing CO2 8Kybp (start of forest clearing)
  and CH4 5Kybp (rice farming). These events
  prevented an ice age that would have naturally
  occurred as a function of changing orbital
  parameters.

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LUCC Summary

• Humans have altered the vegetation landscape on a
  large scale for agricultural (crop cultivation,
  grazing of livestock) and other economic purposes
  (fuel/firewood, urbanization, reclamation,
  etc.).
• Degradation occurs in humid climates
  (deforestation) and arid climates
  (desertification).
• Changes in water resource use can have unintended
  consequences on vegetation.
• Modeling studies suggest large-scale land use
  change can have an affect on regional climate.