Peer-Reviewed Articles
699 The Fragmentation of Space in the Amazon Basin:
Emergent Road Networks
Eugenio Y. Arima, Robert T. Walker, Marcio Sales, Carlos
Souza, Jr., and Stephen G. Perz
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In this article, we simulate forest fragmentation patterns
by reference to the actual decision-making of the agents
engaged in the fragmentation process itself. We take as our
empirical case fragmentation in the Brazilian Amazon basin
associated with road-building by loggers. Roads built by
the private sector, particularly loggers, play a decisive role
in the dynamics of frontier expansion in the Amazon.
Our objective is to explain the manner in which logging
roads manifest spatially, thereby creating fragmented
landscapes in a small portion of the so-called “Terra
do Meio,” a region of 300,000 km2 in the heart of the
Amazon basin. We combine geostatistical methods with
GIS to replicate a common fragmentation pattern found in
tropical forests known as dendritic. Such fragmentation
has been identified as one of the three most common types
observed in the Amazon basin. The model replicates the
general dendritic pattern and many branching points of the
network, although segments do not overlay precisely. The
paper concludes with a discussion of steps necessary to
develop a model that is fully effective in describing the
spatial decision-making of loggers.
711 Multi-Sensor Data Fusion for Modeling African Palm in
the Ecuadorian Amazon
Carolina Santos and Joseph P. Messina
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African oil palm ( Elaeis guinensis) is the most productive
oil seed. Globally, the oil palm industry plans to double
the area under cultivation to meet growing demands for
both vegetable oils and biodiesel. Accurate assessment and
monitoring of African palm extensification and intensification
for both development and sustainability is crucial given that
these crops are replacing the natural high-biodiversity forests
as well as local subsistence agriculture. Using a simultaneous
collection of RADARSAT synthetic aperture radar (SAR) and
ground based digital video, we describe and model the
spatial distribution of African palm and explore its lifecycle
placing it in the regional ecological context of the Ecuadorian,
Amazon. We evaluate the strengths and limitations of integrating
RADARSAT texture information, Landsat ETM+, and digital
video data to distinguish African oil palm plantations from
other land-use and land-cover (LULC) categories. The grey-level
co-occurrence matrix (GLCM) and a separate hybrid classification
approach using a concatenation of SAR-optical products
were tested. A significant improvement in the classification
accuracy of African palm in the context of the Ecuadorian
Amazon was obtained through the fusion of optical and
RADARSAT texture measures as compared to single sensor
classifications. The fusion of single ETM+ bands with texture
measures achieved the highest user’s and producer’s accuracy
with 83 percent and 90 percent, respectively.
725 Integration of Hyperion Satellite Data and
A Household Social Survey to Characterize
the Causes and Consequences of Reforestation
Patterns in the Northern Ecuadorian Amazon
Stephen J. Walsh, Yang Shao, Carlos F. Mena, and Amy L. McCleary
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The integration of Hyperion and Ikonos imagery are used
to differentiate the subtle spectral differences of landuse/
land-cover types on household farms in the Northern
Ecuadorian Amazon (NEA) with an emphasis on secondary
and successional forests. Approaches are examined that
include the use of Principal Components Analysis to
compress the Hyperion hyperspectral data to its most vital
spectral channels; linear mixture modeling to derive subpixel
fractions of land-use/land-cover types through the
generation of spectral endmembers; and supervised and
unsupervised classifications to map forest regrowth, agricultural
crops and pasture, and other land-uses on 18 survey
farms that are spatially coincident with the imagery.
A longitudinal socio-economic and demographic survey
(1990 and 1999) is used to characterize household farms;
a community survey (2000) is used to assess nearby market
towns and service centers; GIS is used to represent the
resource endowments of farms and their geographic accessibility.
Statistical relationships are examined using Spearman
rank correlation coefficients to assess the linkages
among a number of selected social, geographical, and
biophysical variables and secondary and successional forest
on household farms. Relationships suggest the importance
of household characteristics, farm resources, and geographic
access of secondary forests on surveyed household
farms that were previously deforested and converted to
agriculture through extensification processes. Results
support the integrated use of hyperspectral and hyperspatial
data for characterizing forest regrowth on household
farms, and the use of multi-dimensional social survey data
and GIS to assess plausible causes and consequences of
land-use/land-cover dynamics in the NEA.
Color figure 4. (Adobe PDF 19Kb)
737 Trajectories of Land-use and Land-cover in
the Northern Ecuadorian Amazon: Temporal
Composition, Spatial Configuration, and
Probability of Change
Carlos F. Mena
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This paper explores the temporal composition of the main
Land-use/Land-cover (LULC) trajectories, examines the spatial
configuration of the trajectories, and derives the probabilities
of transitions in the Northern Ecuadorian Amazon (NEA).
This research uses a time-series of classified Landsat images
that ranges from 1974 to 2002, and a set of spatial socioeconomic,
demographic, and accessibility data assembled in a
geographic information system. The LULC trajectories are
analyzed for the Northern Intensive Study Area (NISA) using
image algebra, and for the whole region, the NEA, using
cluster analysis, landscape ecology principles, and spatial
logistic regression models. In general, the trajectories are
dominated (i.e., in terms of area) by recent transitions that
contain forested classes (i.e., primary forest or succession),
as well as the consistent representation of pasture through
time. This exploratory analysis of LULC transitions suggests
a set of clusters that form a “core and periphery” pattern
in the NEA. This research shows how these clusters and
probabilities of change can be used to characterize trajectories
of LULC in the region.
Color figure 3. (Adobe PDF 330Kb) Color figure 8. (Adobe PDF 77Kb)
753 Disturbance, Management, and Landscape
Dynamics: Harmonic Regression of Vegetation
Indices in the Lower Okavango
Delta, Botswana
Amy L. Neuenschwander and Kelley A. Crews
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Focused on the Okavango Delta, Botswana, this research
investigates (a) whether ecosystem signals derived from
remotely sensed imagery can be decomposed using a harmonic
regression, (b) if the deviations from the decomposed signal
are correlated with observed flooding and fire regimes, and
(c) the impact of explicitly including agriculture, settlement
areas, and land management systems on the derived signals.
A time-series of 85 TM/ETM+ scenes spanning the period from
1989 through 2002 was used to decompose derived landscape
dynamics into trends, annual and seasonal cycles,
and long term oscillations. The harmonic fit largely defined
by climatic periodicities (semi-annual, annual, and quasidecadal)
accounted for 63 percent to 88 percent of the
variance in the trajectories. The trends were found to be
robust whether or not urban settlement or landscape management
regimes were explicitly included, though there was
a reversal of trend in agricultural areas.
765 Characterizing Patterns of Land Degradation
Potential and Agro-Ecological Sustainability
in Nang Rong, Thailand
William F. Welsh
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Soil crop suitability data was used to characterize and
evaluate land-use/land-cover (LULC) classifications derived
from Landsat TM and MSS imagery for 1997, 1985, and 1972.
Landsat spectral classifications were post-processed using GIS
data into a time-series of pixels that were identified as having
agricultural potential (not including household gardens within
settlements), and then compared with soil suitability variables
to characterize LULC patterns and assess the likelihood of
potential for land degradation within the Nang Rong,
Thailand study area. Results of this estimate indicate that for
extensive areas of upland cash cropping, particularly in the
case of cassava, a significant potential for land degradation
and hence agro-ecological unsustainability exists. Lowland
rain-fed rice cropping, the most areally extensive and temporally
persistent form of agriculture, is revealed to be largely
agro-ecologically sustainable. A trend in the Nang Rong
region is towards planting fast growing eucalyptus trees,
a non-native species known to be damaging to the soil and
ecology, as a cash crop in both upland and lowland settings
for pulpwood, construction framing, and biofuel feedstock,
making future potential land degradation scenarios somewhat
different than in the past and ongoing monitoring critical.
775 Land-cover Change and Vulnerability
to Flooding near Poyang Lake,
Jiangxi Province, China
Luguang Jiang, Kathleen M. Bergen, Daniel G. Brown, Tingting Zhao, Qing Tian, and Shuhua Qi
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Inhabitants near Poyang Lake, in the Central Yangtze River
Basin, China, are vulnerable to loss of life and livelihood
because of the interactions of flooding and land-use policies
and decisions. We analyzed implications of land-cover
patterns for vulnerability to flooding in the Poyang Lake
Region. Land-cover and change were mapped using multitemporal
Landsat TM/ETM+ images at high and low water
levels from 1987, 1993, 1999, and 2004. Vulnerability to
flooding was analyzed based on the distribution of land
covers relative to elevation and the levee quality. Results
showed that patterns of Farmland, Urban, and Wetland
covers varied by elevation, by the relative likelihood of
flooding within polders, and over time; the general trend,
with some notable exceptions, was toward less vulnerability
of farmland and urban areas to flooding. Factors of markets,
laws and regulations have likely influenced changes in landcover
patterns and, therefore, in vulnerability.
787 Changing Regimes: Forested Land Cover Dynamics in
Central Siberia 1974-2001
Kathleen M. Bergen, Tingting Zhao, V. Kharuk, Y. Blam, Daniel
G. Brown, L.K. Peterson, and N. Miller
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The twentieth century saw fundamental shifts in northern
Eurasian political and land-management paradigms, in Russia
culminating in the political transition of 1991. We used the
1972 to 2001 Landsat archive bracketing this transition to
observe change trends in southern central Siberian Russia in
primarily forested study sites. Landsat resolved conifer, mixed,
deciduous and young forest; cuts, burns, and insect disturbance;
and wetland, agriculture, bare, urban, and water land
covers. Over 70 percent of forest area in the three study sites
was likely disturbed prior to 1974. Conifer forest decreased
over the 1974 to 2001 study period, with the greatest decrease
1974 to 1990. Logging activity (primarily in conifers) declined
more during the 1991 to 2001 post-Soviet period. The area of
Young forest increased more during the 1974 to 1990 time
period. Deciduous forest increased over both time periods.
Agriculture declined over both time periods contributing to
forest regrowth in this region.
Color figure 2. (Adobe PDF 121Kb)