Roberto O. Valdivia

Modelling the supply of ecosystem services from agriculture: a minimum-data approach

We argue that to support agriculture–environmental policy decision making, stakeholders need ‘quantitative back-of-the-envelope’ analysis that is timely and sufficiently accurate to make informed decisions. We apply this concept to the analysis of the supply of ecosystem services from agriculture. We present a spatially explicit production model and show how it can be used to derive the supply of ecosystem services in a region. This model shows that the supply of ecosystem services can be derived from the spatial distribution of opportunity cost of providing those services. We then show how this conceptual model can be used to develop a minimum-data (MD) approach to the analysis of the supply of ecosystem services from agriculture that can be implemented with the kinds of secondary data that are available in most parts of the world. We apply the MD approach to simulate the supply of carbon that could be sequestered in agricultural soils in the dryland grain-producing region of Montana. We find that the supply curve derived from the MD approach can approximate the supply curve obtained from a more elaborate model based on site-specific data, and can do so with sufficient accuracy for policy analysis.

Multiple equilibria, soil conservation investments, and the resilience of agricultural systems

This paper provides a new explanation for the persistent land degradation in some parts of the world, despite the availability of seemingly effective soil conservation technologies. We demonstrate that soil conservation technologies may induce agricultural systems to exhibit equilibria characterized by both low and high levels of soil degradation. These two equilibria are separated by a threshold level of soil degradation beyond which a conservation investment will not yield a positive return. Once a parcel of land crosses this productivity threshold, soil degradation becomes economically irreversible (it is not profitable to invest in soil conservation) even though the degradation may be technically reversible. A case study of terracing investments in Peru is used to demonstrate the existence of multiple equilibria under conditions typical of many marginal agricultural areas. These findings help explain why attempts to encourage permanent adoption of soil conservation practices often fail, and how more successful policies could be designed.

New parsimonious simulation methods and tools to assess future food and environmental security of farm populations

This article presents conceptual and empirical foundations for new parsimonious simulation models that are being used to assess future food and environmental security of farm populations. The conceptual framework integrates key features of the biophysical and economic processes on which the farming systems are based. The approach represents a methodological advance by coupling important behavioural processes, for example, self-selection in adaptive responses to technological and environmental change, with aggregate processes, such as changes in market supply and demand conditions or environmental conditions as climate. Suitable biophysical and economic data are a critical limiting factor in modelling these complex systems, particularly for the characterization of out-of-sample counterfactuals in ex ante analyses. Parsimonious, population-based simulation methods are described that exploit available observational, experimental, modelled and expert data. The analysis makes use of a new scenario design concept called representative agricultural pathways. A case study illustrates how these methods can be used to assess food and environmental security. The concluding section addresses generalizations of parametric forms and linkages of regional models to global models.

Minimum-data analysis of ecosystem service supply in semi-subsistence agricultural systems

Antle and Valdivia (2006, Australian Journal of Agricultural and Resource Economics 50, 1–15) proposed a minimum-data (MD) approach to simulate ecosystem service supply curves that can be implemented using readily available secondary data and validated the approach in a case study of soil carbon sequestration in a monoculture wheat system. However, many applications of the MD approach are in developing countries where semi-subsistence systems with multiple production activities are being used and data availability is limited. This paper discusses how MD analysis can be applied to more complex production systems such as semi-subsistence systems with multiple production activities and presents validation analysis for studies of soil carbon sequestration in semi-subsistence farming systems in Kenya and Senegal. Results from these two studies confirm that ecosystem service supply curves based on the MD approach are close approximations to the curves derived from highly detailed data and models and are therefore sufficiently accurate and robust to be used to support policy decision making.

Crop-Livestock Intensification in the Face of Climate Change: Exploring Opportunities to Reduce Risk and Increase Resilience in Southern Africa Using an Integrated Multi-Modeling Approach

The climate of Southern Africa is highly variable at most time-scales and follows a pronounced gradient with arid conditions in the west and humid conditions in the east. There is also a marked latitudinal rainfall distribution pattern, with the southern part having a low rainfall index and high variability and the northern part having higher annual rainfall and lower interannual variability (Kandji et al., 2006). Over the last 100 years, temperatures have increased by about 0.5◦C in the region and downward trends in rainfall have also occurred (Kandji et al., 2006; Morton, 2007). There has also been an increase in drought eventswith over 15 drought events reported in the region between 1988 and 1992. The frequency and intensity of El Nin˜o episodes have increased. Prior to the 1980s, strong El Nin˜o events occurred every 10–20 years; between 1980 and 2000, the region experienced five episodes with the 1982–1983 and 1997–1998 episodes being the most intense of the century (Reason and Jagadheesha, 2005; Rouault and Richard, 2005). These episodes have contributed to stagnant or decreasing agricultural production and worsening food insecurity in the region (Kandji et al., 2006). Unfavorable climatic conditions and projected climate change are among the major obstacles to achieving food security in the region and also have dire consequences for macro-economic performance.

Using AgMIP Regional Integrated Assessment Methods to Evaluate Vulnerability, Resilience and Adaptive Capacity for Climate Smart Agricultural Systems

The predicted effects of climate change call for a multi-dimensional method to assess the performance of various agricultural systems across economic, environmental and social dimensions. Climate smart agriculture (CSA) recognizes that the three goals of climate adaptation, mitigation and resilience must be integrated into the framework of a sustainable agricultural system. However, current methods to determine a systems’ ability to achieve CSA goals are lacking. This paper presents a new simulation-based method based on the Regional Integrated Assessment (RIA) methods developed by the Agricultural Model Inter-comparison and Improvement Project (AgMIP) for climate impact assessment. This method combines available data, field- and stakeholder-based surveys, biophysical and economic models, and future climate and socio-economic scenarios. It features an integrated farm and household approach and accounts for heterogeneity across biophysical and socioeconomic variables as well as temporal variability of climate indicators. This method allows for assessment of the technologies and practices of an agricultural system to achieve the three goals of CSA. The case study of a mixed crop livestock system in western Zimbabwe is highlighted as a typical smallholder agricultural systems in Africa.

Scoping climate change adaptation strategies for smallholder farmers in East Africa - a multi-dimensional, multi-scenario impact assessment

This chapter assesses the characteristics of current and future agricultural systems, land use, agricultural output, output price, cost of production, and farm and household size in response to climate change. This analysis also compared both current and projected future climate (2030), with and without adaptation, and for different socioeconomic scenarios (Representative Agricultural Pathways, RAPs) in two study areas in Kenya. A new approach to impact assessment, the Tradeoff Analysis Model for Multi-Dimensional Impact Assessment (TOA-MD) was adopted for this analysis, which simulated technology adoption and associated economic, environmental and social outcomes in a heterogeneous farm population for a regional impact assessment. These case studies yield new insights into the way that adaptation strategies could improve the livelihoods of smallholder farmers operating in the mixed crop-livestock systems in East Africa.This book emphasis the role of farm level adaptation as a key in developmental pathways that are challenged by climate risks in the semi-arid tropics of Asia and Africa. It throws light on key issues that arise in farm level impacts, adaptation and vulnerability to climate change and discusses Q2 methodological approaches undertaken in study domains of Asia and Africa. The book systematically describes the perceptions, aspirations as elicited/voiced by the farmers and identifies determinants of adaptation decisions. Chapters identify constraints and opportunities that are translated into indicative intervention recommendations towards climate resilient farm households in the semi-arid tropics of Asia and Africa. Furthermore, it discusses with evidences that contributes to the development of livelihood strategy for poor farmers in Asia (Bangladesh, India, Sri Lanka, Thailand, Vietnam and China) and Africa (Burkina Faso, Niger, Kenya and Ghana).