2,783 research outputs found
Remote sensing of opium poppy cultivation in Afghanistan
This work investigates differences in the survey methodologies of the monitoring
programmes of the United Nations Office on Drugs and Crime (UNODC) and the
US Government that lead to discrepancies in quantitative information about poppy
cultivation. The aim of the research is to improve annual estimates of opium production.
Scientific trials conducted for the UK Government (2006–2009) revealed differences
between the two surveys that could account for the inconsistency in results.
These related to the image interpretation of poppy from very high resolution satellite
imagery, the mapping of the total area of agriculture and stratification using full
coverage medium resolution imagery. MODIS time-series profiles of Normalised
Difference Vegetation Index (NDVI), used to monitor Afghanistan’s agricultural
system, revealed significant variation in the agriculture area between years caused
by land management practices and expansion into new areas.
Image interpretation of crops was investigated as a source of bias within the sample
using increasing levels of generalisation in sample interpretations. Automatic
segmentation and object-based classification were tested as methods to improve
consistency. Generalisation was found to bias final estimates of poppy up to 14%.
Segments were consistent with manual field delineations but object-based classification
caused a systematic labelling error. The findings show differences in survey
estimates based on interpretation keys and the resolution of imagery, which is compounded
in areas of marginal agriculture or years with poor crop establishment.
Stratified and unstratified poppy cultivation estimates were made using buffered
and unbuffered agricultural masks at resolutions of 20, 30 and 60 m, resampled from
SPOT-5 10 m data. The number of strata (1, 4, 8, 13, 23, 40) and sample fraction (0.2
to 2%) used in the estimate were also investigated. Decreasing the resolution of the
imagery and buffering increased unstratified estimates. Stratified estimates were
more robust to changes in sample size and distribution. The mapping of the agricultural
area explained differences in cultivation figures of the opium monitoring
programmes in Afghanistan.
Supporting methods for yield estimation for opium poppy were investigated at
field sites in the UK in 2004, 2005 and 2010. Good empirical relationships were
found between NDVI and the yield indicators of mature capsule volume and dry
capsule yield. The results suggested a generalised relationship across all sampled
fields and years (R2 >0.70) during the 3–4 week period including poppy flowering.
The application of this approach in Afghanistan was investigated using VHR satellite
imagery and yield data from the UNODC’s annual survey. Initial results indicated
the potential of improved yield estimates using a smaller and targeted collection
of ground observations as an alternative to random sampling.
The recommendations for poppy cultivation surveys are: the use of image-based
stratification for improved precision and reducing differences in the agricultural
mask, and use of automatic segmentation for improved consistency in field delineation
of poppy crops. The findings have wider implications for improved confidence
in statistical estimates from remote sensing methodologies
Effects of caste on the constitutive and induced expression of genes associated with immunity and detoxification in Formosan subterranean termites
Simms, Dawn M., B.S., Louisiana State University, 1997 Master of Science, Spring Commencement, 2013 Major: Entomology Effects of Caste on the Constitutive and Induced Expression of Genes Associated with Immunity and Detoxification in Formosan Subterranean Termites Thesis directed by Associate Professor Claudia Husseneder Pages in thesis, 74. Words in abstract, 268. ABSTRACT Formosan subterranean termites (FSTs) live in dense populations and nest conditions that are conducive to microbial growth. Furthermore, termites are exposed to potential toxic substances in the soil and in their lignocellulose diet. These characteristics, in combination with the specialized caste system of FSTs, make this termite a valuable model for studying insect immunity and detoxification mechanisms. Since workers forage for food, feed their nest mates and care for the brood, they are more likely than soldiers to encounter pathogens and/or toxins. They must, therefore, be better able to defend against these challenges. This study tested the hypothesis that genes associated with immunity and/or detoxification via xenobiotic metabolism in FST have higher constitutive expression level and/or are more readily inducible in workers than in soldiers. FST workers and soldiers were challenged either by bacterial injection or by no-choice feeding with a sublethal concentration (0.5%) of Phenobarbital. Constitutive and induced expression of 5 putative immune response and 5 detoxification genes was measured via quantitative real time qRT-PCR and compared within and between 1) colonies, 2) treatment groups and 3) castes via non-parametric, multivariate analysis of variance. Of the 10 total target genes, none were found to be differentially expressed as an effect of colony. However, treatment type had a significant (P\u3c 0.05) effect on the expression of each of the 8 target genes that were inducible. Caste effects on expression levels were significant in 6 of the 8 inducible target genes. In many cases, target genes were only inducible in the worker caste. Overall, constitutive and induced expression of target genes was significantly higher in workers than in soldiers
The application of time-series MODIS NDVI profiles for the acquisition of crop information across Afghanistan
We investigated and developed a prototype crop information system integrating 250 m Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) data with other available remotely sensed imagery, field data, and knowledge as part of a wider project monitoring opium and cereal crops. NDVI profiles exhibited large geographical variations in timing, height, shape, and number of peaks, with characteristics determined by underlying crop mixes, growth cycles, and agricultural practices. MODIS pixels were typically bigger than the field sizes, but profiles were indicators of crop phenology as the growth stages of the main first-cycle crops (opium poppy and cereals) were in phase. Profiles were used to investigate crop rotations, areas of newly exploited agriculture, localized variation in land management, and environmental factors such as water availability and disease. Near-real-time tracking of the current years’ profile provided forecasts of crop growth stages, early warning of drought, and mapping of affected areas. Derived data products and bulletins provided timely crop information to the UK Government and other international stakeholders to assist the development of counter-narcotic policy, plan activity, and measure progress. Results show the potential for transferring these techniques to other agricultural systems
Opium yield estimates in Afghanistan using remote sensing
Accurate estimates of opium production are essential for informing counter-narcotics policy in
Afghanistan. The cultivated area of opium poppy is estimated remotely by interpretation or digital
classification of very high resolution (VHR) satellite imagery at sample locations. Obtaining an accurate
estimate of average yield is more challenging as poor security prevents access to a sufficient
number of field locations to collect a representative sample. Previous work carried out in the UK
developed a regression estimator methodology using the empirical relationship between the remotely
sensed normalised difference vegetation index (NDVI) and the yield indicator mature capsule volume.
The application of the remote sensing approach was investigated in the context of the existing
annual opium survey conducted by the United Nations Office on Drugs and Crime and Afghanistan’s
Ministry of Counter Narcotics (UNODC/MCN) and indicated the potential for bias correction of yield
estimates from a small targeted field sample. In this study we test the approach in Afghanistan using
yield data and VHR satellite imagery collected by the UNODC/MCN surveys in 2013 and 2014.
Field averaged measurements of capsule volume were compared to field averaged NDVI extracted
using visual interpretation of poppy fields. The study compares the empirical relationships from the
UK field trials with the Afghanistan data and discusses the challenges of developing an operational
methodology for accurate opium yield estimation from the limited sample possible in Afghanistan
Survey and monitoring of opium poppy and wheat in Afghanistan: 2003-2009
An integrated application of remote-sensing technology was devised and applied in Afghanistan during 2003–2009 providing critical information on cereal and poppy cultivation and poppy eradication. The results influenced UK and international policy and counter-narcotics actions in Afghanistan
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