Pressure State Response Systems

The PSR framework is based on the fact that human activities exert Pressures on the environment (such as pollution, land use change, or increased demand for livestock products). These result in changes in the State of the environment (e.g. changes in pollutant levels, habitat diversity, livestock production, etc.) which in turn result in Impacts.  Society's Response to changes in pressures or state is then with environmental and economic policies or programs intended to prevent, reduce or mitigate the pressures and/or environmental and socio-economic damage that occurred as a result of the original pressures.

The OECD Pressure-State-Response (PSR) model Driving Forces and Impacts: Development of the DPSIR model Changes in State in Livestock Systems References and Further Reading

Far too often, short-sighted or badly informed decisions are targeted not at the original pressures, but at the symptoms exhibited by the changed state. Without considering the pressures, and the driving forces behind them, such measures are almost always doomed to failure.

The Pressure-State-Response (PSR) model, developed by OECD, provides a mechanism to monitor the status of the environmental. The PSR cycle also provides a framework for investigation and analysis of processes involved in environmental degradation. It has gained international prominence and can be applied at a national level, for sectoral analysis, at regional, local and other sub-national levels, and at an individual project level. The framework arises from a simple set of questions:

The PSR model considers that human activities exert pressures on the environment that affect its quality and the quantity of natural resources (state). Society then responds to these changes through environmental, general economic and sectoral policies, and through changes in awareness and behaviour or activities (societal response).

Indicators are an integral part of the PSR framework and assist with overall analysis in the following areas:

There are also a number of important points to bear in mind when using indicators:

• Without good data, based on regular monitoring, it is not possible to develop reliable indicators.
• Performance measures imply that targets need to be set (i.e. something against which performance can be compared).
• Different people living in different places have different values and different requirements. Indicators must therefore be able to take into account different locations, people, cultures and institutions.
• Sets of indicators evolve over time.
• Sets of indicators are seldom, if ever, complete.
• Measurement of indicators tends to reduce uncertainty, but does not eliminate it.
• Indicators can play an important part in the way in which human influences on the environment operate. Changing the indicators may also change the system.

The PSR framework is now widely used but is continuing to evolve. An important requirement is the need to clearly differentiate between pressure and state indicators, and the need to expand the framework to deal more specifically with the needs for describing sustainable development. Inclusion of Driving Forces on the one hand and Impacts on the other has broadened the scope of the model - but the core principles remain the same. The Driving Force - Pressure - State - Impact - Response (DPSIR) framework provides an overall mechanism for analyzing environmental problems. In this modified system:

	Driving Forces such as population increase, industrial development, urbanization and transport, produce
	Pressures on the environment, such as pollution caused by excess manure from livestock, which then degrade the
	State of the environment, which then result in
	Impacts on human health and the health eco-systems, causing society to
	Respond with various policy measures, such as regulations, information and taxes, which can be directed at any other part of the system.

With respect to the environmental impact of livestock keeping, major issues for consideration or observed changes in state of livestock-environment interactions include for following (adapted from Fleischhauer et al.):

Unfavourable changes in vegetation composition and structure as a result of overgrazing. In the drylands, vegetation yield may be low, not because of livestock but because of low rainfall, and vegetation may recover quickly when rainfall improves. Where grazing predominates, animals will die before the vegetation is irreversibly damaged, but supplementary feeding can result in overgrazing. This risk is much higher in mixed farming than in pastoral systems.

In more humid regions, deforestation may be associated with livestock production - although usually the direct links are with large stock, not smallstock. Deforestation for livestock purposes is relevant mainly in Latin America. The causes are complex and are often the result of policy distortion and less by livestock production in the narrow sense. Deforestation in Asia and Africa is mainly due to expansion of cropping area and plantation crops.

Nutrient flows within farming systems. This is particularly important in mixed farming systems. Some nutrients are added to cropland via manure, but this can impoverish the rangelands and may not offset the nutrient losses from cropping. Feed production areas are not directly linked with livestock feed use, leading to a transfer of nutrients from feed producing areas to areas with high livestock concentration. On the one hand there is a nutrient deficit (this can be thought of a mining the nutrients) and on the other hand there is nutrient surplus - which leads to pollution, especially in industrial systems.

Nutrient accumulation in industrial systems, where concentrate feeds may even come from other continents. This is common in industrial landless systems and can pollute water or overload soils with nutrients. The tremendous regional imbalances jeopardize the ecological equilibrium in a way similar to pollution from heavy industry.

Industrial production can create enormous pollution problems because it brings in large quantities of nutrients in form of concentrate feed and then has to dispose of the manure to nearby land which quickly becomes saturated. As a result, land and groundwater are polluted.

Transmission of disease among animals and between livestock and humans. The widespread use of antibiotics, not only to prevent or cure diseases but also to promote animal growth, leads to the development of resistant bacteria and germs and may jeopardize the possibilities to use antibiotics to cure infections in humans. This is a particular risk in intensive, industrial systems of animal production. Also new diseases, such as BSE, and the increasing salmonella infections of food are mainly linked to industrial systems.

High inputs of fossil energy and unfavourable input-output ratios. This is especially true for systems with high-yielding animals, requiring concentrates and forages produced with high fertilizer inputs. The current low price of fossil energy promotes the extensive use of these high input - high output systems, and also introduces greater risks of disease transmission between livestock and humans.

Biodiversity of flora and fauna, including that of domestic animals. Biodiversity is closely linked to eco-system resilience, yet understanding of these linkages is still poor and particularly so at policy making levels. With respect to domestic animals, the difference between nutritional and veterinary requirements between different breeds and the subsequent difference in impact on the environment should be taken into account. Similarly, different breeds have differing abilities to withstand and combat parasites and diseases.

Industrial livestock production in particular and also livestock production in mixed systems use a very limited range of animal breeds. This has already led to the extinction of some local livestock breeds and the genetic erosion of others. Specific genetically determined capacities in local breeds to cope with the climatic, nutritional and disease challenge may already have been lost.

Climate Change. Greenhouse gases contributing to global warming. Greenhouse gases, of which about 5–10 percent are produced by livestock and livestock waste, contribute to global warming. Climate change is likely to have significant impacts on livestock production. Methane from ruminant livestock is produced by bacteria in the animals' digestive systems that break down fibrous foods. The methane gas is then released into the atmosphere. The decomposition process in liquid manure management used in intensive systems, especially pigs, also produces and releases methane into the atmosphere.

Fleischhauer, E., Bayer, W. and Von. Lossau, A. Assessing and Monitoring Environmental Impact and Sustainability of Animal Production. In: Proceedings of the International Conference on Livestock and the Environment held in Ede/Wageningen, the Netherlands 16 - 20 June 1997, organized by World Bank Food and Agriculture Organization International Agricultural Centre.