Livestock systems/Data uncertainties limitations: Difference between revisions

Revision as of 14:57, 10 February 2014

Parts of Livestock systems/Data uncertainties limitations

Component is implemented in:

IMAGE land management model (version IMAGE land management 3.2)

Components:

Related IMAGE components

Projects/Applications

Models/Databases

MAGNET model

Key publications

Bouwman et al., 2005

References

Flowchart Livestock systems. See also the Input/Output Table on the introduction page.

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 {{ComponentDataUncertaintyAndLimitationsTemplate
 |Reference=FAO, 2012; Beusen et al., 2008; Bouwman et al., 2005; Seré and Steinfeld, 1996;
 |Description=<h2>Data</h2>
-Data on animal stocks, milk production per animal, off-take rates and carcass weights, for the 1970–2005 period, are obtained from the [[FAO]] ([[FAO, 2012]]). Different animal production systems, and their  total population and production have been defined in recent FAO publications ([[Seré and Steinfeld, 1996]]). For ruminants, these production systems include pastoral, mixed and landless production, for various agro-ecological zones. We aggregated the data to two broad groups: pastoral and mixed + landless production systems. The data are provided for 7 large world regions, which we subsequently disaggregated to the level of the 24 world regions in the IMAGE model ([[Bouwman et al., 2005]]). [[Seré and Steinfeld, 1996]] also provided data for the growth in animal populations and the production in each production system.
+Data: Livestock numbers, milk production per animal, off-take rates and carcass weights for the 1970–2005 period were obtained from [[FAO]] ([[FAO, 2012]]). Various animal production systems, and the total livestock population and production have been defined in recent FAO publications ([[Seré and Steinfeld, 1996]]). For ruminants, these production systems include pastoral, mixed and landless production in various agro-ecological zones. These data have been aggregated to two systems:  pastoral, and mixed & landless production systems, and disaggregated from seven world regions to the 24 world regions in the IMAGE model ([[Bouwman et al., 2005]]). [[Seré and Steinfeld, 1996]] also provided data on the growth in livestock populations and on production in each production system.
 ==Uncertainties==
-There are several uncertainties involved in the calculation of livestock production in the different systems, both for historical years and scenarios. The first uncertainty is the aggregation level on the scale of countries and world regions, whereby all underlying heterogeneity is ignored. A second problem is the use of average data for carcass weight, off-take rate, and milk production for complete animal populations. In reality, animal populations include different age classes, and only part of a population is productive. Some calculations, such as on the energy requirement for maintenance, are a non-linear function of body weight. Using average values, therefore, may not be correct.
+There are several uncertainties in the calculation of livestock production in the different systems for historical years and scenarios. The first uncertainty is the aggregation level on the scale of country or world region, which does not take account of underlying heterogeneity. The second uncertainty concerns the use of average data for carcass weight, off-take rate, and milk production for total livestock populations. In reality, livestock populations cover different age classes, and not all animals in a population are productive. Calculations, such as energy requirement for maintenance, are a non-linear function of body weight, and thus use of average values, may lead to distortion. The third uncertainty is associated with livestock numbers. Methodology and frequency of data collection (for example, by census) vary between countries, and are probably less certain for some developing countries than for industrialised countries. This uncertainty on livestock numbers affects not only the livestock module, but also all impact IMAGE modules that depend on livestock numbers, such as ammonia emissions ([[Beusen et al., 2008]]).
-A further uncertainty is associated with animal stocks. Methodology and frequency of data collection (e.g. by census) vary between countries, and are probably less certain for some developing countries than for industrialised countries. Uncertainties in this part of IMAGE as well as in other parts, such as those with respect to ammonia emissions, are strongly related to animal stocks ([[Beusen et al., 2008]]).
 The main uncertainties in construction scenarios concern agricultural demand ([[Agricultural economy and forestry]]), the distribution of production over the two systems, and production characteristics per system, including feed requirements and feed types.
 ==Limitations==
-One important limitation is that the development of ruminant livestock system characteristics is purely following a scenario storyline and has no explicit link to the agricultural economy, or for example to land scarcity. This is partly due to the fact that livestock systems in the [[MAGNET model]], so far, have been represented rather weakly, and the model does not include explicit, physically based feed compositions. The two models are coupled only for the calculation of grassland area.
+The key limitation in the current livestock module is that the ruminant livestock system have a soft linkage to the agricultural economy model MAGNET ([[Agricultural economy and forestry]]). Although [[MAGNET model|MAGNET]] has some representation of feed substitution and intensification as a result of land scarcity, and mimics the dynamics described here, there is no explicit representation of livestock systems, and physically based feed compositions.
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Livestock systems/Data uncertainties limitations: Difference between revisions

Revision as of 14:57, 10 February 2014

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