The use of indicators in soil erosion and protection

Transcription

1 The use of indicators in soil erosion and protection A.C. Imeson IBED-University of Amsterdam, Netherlands 1. Introduction Indicators are a quantitative and easily measurable variable that in some way enables critical aspects of the behaviour of complex systems to be measured in a very simple way. The purpose of this briefing paper is to discuss the use being made of indicators and indicator concepts in soil erosion, soil protection and conservation. During the last two or three decades, the need for soil erosion indicators has considerably increased. This is a reflection of the greater appreciation of the complexity with which soil conservation and protection are being perceived. Increased insights into the nature and complexity of soil conservation and protection have resulted in a more holistic vision of the issues. However, at the same time this places more demands on non-specialists who want to access and act upon this knowledge. Indicators are seen as being needed as tools of communication that can connect science with both policy and affected people. Consequently, although fundamentally the basic requirements of indicators has remained unchanged, in practise they must overcome far greater challenges. Recently, an extensive review has been made of desertification indicators by Brandt et al. (2003). Some of the ideas presented here have been developed from this and other reports which are in press. This briefing paper is not a scientific journal paper but a discussion document. Communicating and explaining indicators is difficult because so many studies are being done in parallel, Soil erosion indicators can be confusing unless the reasons for these different parallel approaches are appreciated. 2. The Challenge: why soil erosion indicators are needed at all? A challenge with soil erosion and conservation is that scientific progress requires new questions to be asked and old questions to be framed in a different way. In the recent past soil erosion and conservation scientists have focussed on developing tools or models to predict or combat erosion, but they have done this from perspectives that can now be regarded as limited in terms of soil policy requirements. When policy focussed on identifying where soil erosion was a problem and how much this was costing, during the early part of the policy cycle, this did not matter too much. This is no longer the case when actions need to be prescribed for preventing erosion and protecting the soil. These actions involving billions of Euro s and voter s emotions need both scientific and political legitimisation. In this domain there are three practical challenges that indicators must meet. The first is to protect and conserve the soil before erosion has damaged or removed it. This requires early-warning. Are the proposed soil monitoring systems up to this 195

2 task? Do new developments in GMS enable emerging problem areas to be timely identified and dealt with? The second challenge is to promote sustainable land use practises that make erosion unlikely or virtually impossible. Much effort is being put into this area but still there is perhaps an overemphasis being placed on biodiversity as general indicator of sustainability and too often soil loss, erosion and runoff are politically linked to arguments that promote the needs of combating global climate change rather than being simply associated with poor (non-sustainable) land use management and planning. The challenge faced by indicators is in the area of evaluation. Particularly it will be necessary to monitor the efficiency and effectiveness of soil conservation and protection actions. Here, indicators that enable reference or base level conditions to be documented are needed (see for example Pellent, 2002) When and where are indicators needed? Actions to prevent and control soil erosion are only needed on a relatively small percentage of the total area and even then for only a limited number of years. In facing the challenges mentioned above, it should be apparent that human actions are driving erosion and making it possible at a specific location for a limited period of time. Whether or not erosion will actually occur often depends on the chance that critical conditions will be met. The actualisation critical conditions are dependent on what people do; on how the land is used and managed. Today serious soil erosion is only an actualised problem on a relatively small area in Europe. Even in areas undergoing severe erosion, 95 per cent of the soil being lost is from only a few per cent of the total area. Policies should enable the affected areas to be targeted. Soil erosion resulting from some kind of human action will continue until it is regulated by some feedback that leads to it being stopped. For example, a traditional feedback would be that because erosion reduces the soil productivity, the activity would be abandoned as the land lost value as capital. The soil might either recover or be degraded. However, in practise feedbacks are influenced by perceptions choices and values. If soil loss is regarded by society as evil, society may intervene. If it occurs through ignorance (the ability to appreciate or understand the long-term consequences of an act that is environmentally destructive) this is adequately explained in a Socretean dialogue. In conclusion, what is really needed is a general and easily understood and explained framework for understanding and integrating soil erosion and conservation issues as part of the overall framework for finding solutions to the challenge of sustainable land use. In some ways frameworks for explaining erosion have existed for a long time and these have also been formulated into models such as the Universal Soil Loss Equation. There are many concepts such as Erosivity and Erodibility and even of Protective Vegetative Cover from this framework that have been used to define very successful erosion indicators. These can be evaluated by indicators such as the Fournier erosivity index (p2/p), the IE30 index and the C Factor from the Wischmeier (1978) equation. In the case of erodibility, this can be done using the k factor or soil aggregation indices. Although, it is true that indicators such as these may be useful for and identifying and analysing potential problems or hot spots, and for comparing the effectiveness of different soil protection strategies, they are only relevant for a very 196

3 limited range of processes and issues. Frequently, the boundary conditions and requirements that should be met before this model is applied are not met. Deterministic modelling frameworks that integrate the effects of different erosion processes have been developed but they have not usually been very successful in predicting measured erosion rates. The problem is that in most cases models try to model the erosion caused by individual rainfall events. Field measurements of erosion have shown that actual soil loss is extremely sensitive to the initial conditions of soil moisture as well as to all kinds of biological processes and the interactions between organisms and the soil that it is these influences that need to be taken into account. A conceptual framework for understanding erosion needs to be focussed on the activities of both people and organisms upon which erosion is contingent. One framework that attempts this is the adapative management metaphor. 2. Indicators for addressing different concerns These challenges of indicators can be examined from the perspectives of who is expressing the concern for the need of soil erosion or soil conservation indicators. Three types of concern can be formulated: according to whether they are scientific or technical, policy driven or victim related. 2.1 Scientific Concerns and soil erosion indicators Scientific concerns relate to the legitimacy of indicators. A simple indicator of soil erosion requires a simple and accurate definition of the erosion that it is to indicate. This is very difficult because in the real world it requires defining both the temporal and special scales and exactly what is meant by erosion. If we start by disaggregating an erosion problem into DPSIR this takes us away from the holistic framework that is needed to make the choice of indicators self-evident. As well as being effective and efficient indicators should be valid. The challenge here is to admit that the general scientific understanding of erosion in the context of adaptive management and sustainable land use has progressed sufficiently for the soil erosion community to realise that a large percentage of the data and soil erosion models has become outdated or of mainly historic interest. New monitoring and earth observation technologies should provide alternative ways of providing the validation that indicators need. Indicators describe what people see. Some alternative ways of approaching indicators are named in table 1 and these can be seen as providing ways of transcending problems of integration, variability and intersite comparability. The first is to look at indicators in terms of functions: How well is the soil performing its soil and water conservation function and how is this threatened. The second relates to natural capital in the soil and landscape. Is this being maintained and replaced? These and some other scientific concerns are briefly mentioned in the table below. 197

4 This is what is observed Typical Questions and concerns Useful Approaches to indicators Loss of functions and quality Loss of viability Evidence of changes in state and condition Evidence from Critical factors affecting erosion Loss of resilience Is it working Are the critical functions of the soil being lost thus threatening sustainability? Is the present exploitation of the soil sustainable? Is the natural economic and ecological capital being maintained? Is there a soil erosion problem today or one that is imminent? Are critical threshold values of factors known to influence? erosion being reached? Can the soil remain within its current state of attraction? Am I doing what I promise and does it help? Soil water regulating and production functions (see Imeson, 2000) Loss of soil, organic matter and biodiversity Indicators of rangeland health (see Pellent et al., 2000) Erosivity, erodibility, cover, slope, carrying capacity etc State and Transition thresholds schemes Adaptive management Panarchy Compliance indicators. Bottomup indicators. Do-it-yourself Table 1. Some different ways of approaching indicators to address typical concerns For example, the soil may be thought of as performing environmental functions or services to people or society. Soil quality indicators enable soils to be evaluated in terms of the provision of these functions. The notion of health is applied by comparing the differences between soils that have had their functions degraded and those that are from healthy reference areas. This approach has recently been adopted and applied to all of the rangelands throughout the United States (Pellent et al 2002). An essential aspect of the soil quality and ecosystem health approach towards indicators is that they are both subjective, reflecting the values and culture of the user. Because the indicator is intimately linked to the user, and because all situations are complex but unique, it is not possible to compare areas by means of the actual values of what is measured but instead in terms of the way in which functions are being performed. The adopting of the rangeland health indicator programme in the USA is a major development that has been reported by the author elsewhere. This scheme could be used for rangelands in Europe and it has been applied by Imeson (2000) in a pilot study in Portugal. 2.2 Policy Concerns Top- down: Indicators for management and control Somewhat different is the need for indicators arising from the demand to monitor and control things such as the condition of the environment or the compliance to regulations and guidelines. Policy makers need to know if policy is effective, efficient and socially acceptable. Because of the cost in collecting the information and data 198

5 needed, there is pressure to provide relatively few headline indicators that can be used to propose targets to which policy can aim. Because of the use to which they are being put, these indicators can best be quantitative and based on reliable data about which there is general acceptance. Ideal sources of such data are earth observation data, river monitoring stations, or statistical data collected by responsible authorities. DG XI commissioned studies on the Environmental Impact of different types of land use in the European Union. One of these on Arable Crop Production (Boatman et al., 1999) based many of its conclusions on research on indicators that were presented in Target area studies of the Medalus Project in Portugal. This demonstrated that research results from previous projects are an extremely important source of knowledge as they provide historical baselines for evaluating trends and impacts and for underpinning the choice of indicators. DPSIR Many environmental issues can be explained from a kind of systems perspective that is in some ways very useful because it links the effects (impacts) to the causes (pressures and drivers) as well as the solutions (responses). This is very convenient for agencies or organisations such as the OESO and the Environmental Agency who want to demonstrate and communicate progress being made in identifying and dealing with the problems that are within their mandates. This is described by Wilson and Buller (2001) as a Typological indicator hierarchy developed by the OECD from about 1993 onwards and described and developed in various OECD publications, for example see OECD (1998). This approach has been favoured by statistical services such as Eurostat and by the European and National Environment Agencies. It is currently being applied to the European Soil Strategy. Its application to erosion by the EEA is described in detail in EEA (2003) and it is being used also for its proposals for a monitoring framework for Europe (Soilnet). This is quite different from the framework described by DG-AGR (2001). It is a problem that although a specific case of an issue (e.g. soil erosion in Italy) could be analysed in terms of DPSIR, the most appropriate indicators would depend completely on the scale and context of the specific case. Moreover, these indicators are unlikely to have a similar meaning or value outside of the specific case being considered. In other words DPSIR indicators are obtained by abstraction for the case in hand. These have to be considered at the appropriate level of the generalisation. They can not be validated or used at the detailed scale from which they were abstracted because there is as yet no way doing this. The UN Sustainable Development programme found that it was much more effective to focus more on the issues. The first cut should be in relation to the concerns of people in the light of the issues such as for example soil loss and forest fires. In the real situations when the causes of erosion are obvious the DPSIR checklist may be extremely useful and valuable for describing problems. This does not mean though that it is a good source of practical indicators. An excellent overall headline indicator could stand alone without being buried in noise produced by other indicators that are decided on in committee and where have influenced the outcomes. A basic issue concerns the political legitimacy of soil erosion and conservation indicators that policy makers must take into account. 199

6 2.3 Indicators for those being affected by erosion Guidelines for using desertification indicators were put forward by the UNCD Committee for Science and Technology (UNCCD) and much of what is said is valid for combating soil erosion. One of the critical requirements of the UNCCD was that people in the affected areas should be able to measure their own indicators and apply these to their own situation. Both identify the threats but also to see if the actions being taken, were effective in combating desertification. In practise, in areas experiencing land degradation such as Cinque Terra, intuitively people, aware of the degradation and erosion of the terraces have been collecting data and information that have been extremely effectively used as indicators to mobilise the commitment to soil conservation and protection. When people have a strong relationship with the land and have a sense of place and history this brings with it an understanding of the changes that are taking place and a discussion of indicators is largely academic. However, when this link is absent, indicators may raise awareness of changes and the responses that can be taken. The photographic evidence and written records of the changes at Cinque Terra are excellent indicators. The Desertlinks (Brandt et al., 2003) indicator system has been designed so that it can be entered by anyone with a concern about desertification. Headline indicators of erosion and soil conservation At the SCAPE workshop some headline indicators for soil erosion will be defined and lists of recommended indicators presented in more detail for discussion. References Boatman N, C.Stoate, R.Gooch, C. R. Carvalho, R. Borralho, G.de Snoo and P.Eden (1999) The Environmental Impact of Arable Crop Production in the European Union, Practical Options for Improvement. Brandt, et al (2003) The Desertlinks Indicator System (CD-ROM). DG- Agriculture 2001 A framework for indicators for the economic and social dimensions of sustainable agriculture and rural development (39 p). EEA Assessment and Reporting on soil erosion (2003) Technical Report 94 (edited by A.R. Gentile). Imeson, A.C Soil degradation: the data problem and its solution pp in Desertification Convention Data and information requirements. Edited by Enne, S.Peter and D. Pottier Imeson, A.C Indicators for land degradation in the Mediterranean basin. pp in Enne G., Zanolla Ch and D.Peter. Desertification in Europe. Mitigation strategies and land use planning EUR 19390, 509p. Organisation for Economic Cooperation and Development (OECD) Towards Sustainable Development Environmental Indicators (ORCD Paris). Pellent M. Shaver P, Pyke, D.A. Herrick, J.E (2000) Interpreting indicators of Rangeland Health (Technical Reference ) United States Department of the Interior 45 p. Wilson G.A. and H.Buller The use of socioo-economic and environmental indicators in assessing the effectiveness of EU Agri-Environmental Policy. European Environment