George A. Dyer

Subsistence Response to Market Shocks

Microeconomic models posit that transaction costs isolate subsistence producers from output market shocks. We integrate microeconomic models of many heterogeneous households into a general equilibrium model and show that supply on subsistence farms may respond, in apparently perverse ways, to changes in output market prices. Price shocks in markets for staple goods are transmitted to subsistence producers through interactions in factor markets. In the case presented, a decrease in the market price of maize reduces wages and land rents, stimulating maize production by subsistence households; however, real incomes of subsistence households fall.

Multiple Pathways of Commodity Crop Expansion in Tropical Forest Landscapes

Commodity crop expansion, for both global and domestic urban markets, follows multiple land change pathways entailing direct and indirect deforestation, and results in various social and environmental impacts. Here we compare six published case studies of rapid commodity crop expansion within forested tropical regions. Across cases, between 1.7% and 89.5% of new commodity cropland was sourced from forestlands. Four main factors controlled pathways of commodity crop expansion: (i) the availability of suitable forestland, which is determined by forest area, agroecological or accessibility constraints, and land use policies, (ii) economic and technical characteristics of agricultural systems, (iii) differences in constraints and strategies between small-scale and large-scale actors, and (iv) variable costs and benefits of forest clearing. When remaining forests were unsuitable for agriculture and/or policies restricted forest encroachment, a larger share of commodity crop expansion occurred by conversion of existing agricultural lands, and land use displacement was smaller. Expansion strategies of large-scale actors emerge from context-specific balances between the search for suitable lands; transaction costs or conflicts associated with expanding into forests or other state-owned lands versus smallholder lands; net benefits of forest clearing; and greater access to infrastructure in already-cleared lands. We propose five hypotheses to be tested in further studies: (i) land availability mediates expansion pathways and the likelihood that land use is displaced to distant, rather than to local places; (ii) use of already-cleared lands is favored when commodity crops require access to infrastructure; (iii) in proportion to total agricultural expansion, large-scale actors generate more clearing of mature forests than smallholders; (iv) property rights and land tenure security influence the actors participating in commodity crop expansion, the form of land use displacement, and livelihood outcomes; (v) intensive commodity crops may fail to spare land when inducing displacement. We conclude that understanding pathways of commodity crop expansion is essential to improve land use governance.

Dispersal of Transgenes through Maize Seed Systems in Mexico

Objectives Current models of transgene dispersal focus on gene flow via pollen while neglecting seed, a vital vehicle for gene flow in centers of crop origin and diversity. We analyze the dispersal of maize transgenes via seeds in Mexico, the crops cradle. Methods We use immunoassays (ELISA) to screen for the activity of recombinant proteins in a nationwide sample of farmer seed stocks. We estimate critical parameters of seed population dynamics using household survey data and combine these estimates with analytical results to examine presumed sources and mechanisms of dispersal. Results Recombinant proteins Cry1Ab/Ac and CP4/EPSPS were found in 3.1% and 1.8% of samples, respectively. They are most abundant in southeast Mexico but also present in the west-central region. Diffusion of seed and grain imported from the United States might explain the frequency and distribution of transgenes in west-central Mexico but not in the southeast. Conclusions Understanding the potential for transgene survival and dispersal should help design methods to regulate the diffusion of germplasm into local seed stocks. Further research is needed on the interactions between formal and informal seed systems and grain markets in centers of crop origin and diversification.

The Economics of Ecotourism: A Galapagos Islands Economy-Wide Perspective

Ecotourism, the fastest growing sector of the largest industry on earth, is strongly advocated by major conservation groups as a way to help conserve nature. Its potential for generating income while creating incentives for conservation has sparked academic discussion regarding the meaning of ecotourism and attention to the design of integrated conservation and tourism projects. With a few exceptions, economists have been absent from these discussions. The World Conservation Union (IUCN) and the Ecotourism Society define ecotourism as “responsible travel to natural areas that conserves the environment and sustains the well-being of local people.” A basic premise of this article is that there may be trade-offs between these two goals. Expanding tourism can generate pressures for demographic growth by widening the economic disparities between tourist destinations and outside economies, stimulating migration to fill jobs linked directly or indirectly to tourism. This may create a tourism-income-population growth spiral at nature destinations inviting to tourists. Researchers have observed what appears to be a strong association between tourism and local population growth. A few economists have assessed ecotourism’s potential for generating income, but economic research into ecotourism’s impacts and its potential for creating conservation incentives is sparse. Current insights along these lines come primarily from noneconomists. Sven Wunder notes that “when economic aspects are treated, it is mostly without quantification that would allow for a

Agricultural Price Policy, Employment, and Migration in a Diversified Rural Economy: A Village-Town CGE Analysis from Mexico

Using the village-town computable general equilibrium (CGE) model this paper explores the implications of resource mobility across farm and non-farm activities and alternative model closure rules in shaping agricultural policy impacts. Two sets of agricultural policy experiments on three alternative model-closure scenarios were conducted using data from a 1993 survey of 196 households in Michoacan Mexico including 53 in a town or county seat and 143 in the surrounding villages. Experiment 1 simulates the village-town economy-wide impact of a 10% decrease in the support price for staples. Experiment 2 combines this support-price decrease with a compensating lump-sum income transfer to staple producers similar to what actually occurred under Mexicos PROCAMPO program. Results show that the prediction made by the aggregate CGE model that Mexicos agricultural price liberalization reduces rural employment and incomes and stimulates migration was not materialized. The decline in staple production has been relatively small and it has concentrated on large commercial farms rather than in small-farm sector in which most producers are found and from which most migrants originate. However with the use of village-town model and microsurvey data the authors demonstrated that under plausible market closure conditions Mexicos staple price liberalization has a minimal effect on rural wagers and migration. This is contrary to the predictions of the aggregated CGE model.

Migration and the Sending Economy: A Disaggregated Rural Economy-Wide Analysis

Abstract Most economic research on migration impacts focuses on the households that send the migrants and get the remittances, ignoring linkages with others in the sending economies. This paper offers an alternative, disaggregated economy-wide perspective on migration and its impacts. Data from the 2003 Mexico National Rural Household Survey are used to calibrate a series of interacting rural household models nested within a general equilibrium model of the whole rural economy. Simulations reveal that the impacts of international migration and remittances on sending areas depend critically on the ways in which local markets transmit influences among households.

Genetic erosion in maize’s center of origin

Significance Unlike germplasm banks, on-farm conservation allows crops to evolve continuously in response to changing conditions. Agricultural adaptation to climate change, emerging pests, and diseases thus depends on conserving crop genetic diversity in situ. However, increasing awareness of these issues has not translated into effective conservation policies. We find that previous assessments of on-farm maize diversity in Mexico are flawed and conceal widespread genetic erosion that could thwart current food security strategies for climate adaptation. Unable to mitigate declining yields by recourse to diversity, farmers might abandon agriculture, leading to a vicious cycle of yield and diversity losses. A reassessment of the conservation status in other centers of crop diversity is similarly urgent but could take a decade given data requirements. Crop genetic diversity is an indispensable resource for farmers and professional breeders responding to changing climate, pests, and diseases. Anecdotal appraisals in centers of crop origin have suggested serious threats to this diversity for over half a century. However, a nationwide inventory recently found all maize races previously described for Mexico, including some formerly considered nearly extinct. A flurry of social studies seems to confirm that farmers maintain considerable diversity. Here, we compare estimates of maize diversity from case studies over the past 15 y with nationally and regionally representative matched longitudinal data from farmers across rural Mexico. Our findings reveal an increasing bias in inferences based on case study results and widespread loss of diversity. Cross-sectional, case study data suggest that farm-level richness has increased by 0.04 y−1 nationwide; however, direct estimates using matched longitudinal data reveal that richness dropped −0.04 y−1 between 2002 and 2007, from 1.43 to 1.22 varieties per farm. Varietal losses occurred across regions and altitudinal zones, and regardless of farm turnover within the sector. Extinction of local maize populations may not have resulted in an immediate loss of alleles, but low varietal richness and changes in maize’s metapopulation dynamics may prevent farmers from accessing germplasm suitable to a rapidly changing climate. Declining yields could then lead farmers to leave the sector and result in a further loss of diversity. Similarities in research approaches across crops suggest that methodological biases could conceal a loss of diversity at other centers of crop origin.

Modelling Agricultural Trade and Policy Impacts in Less Developed Countries

This paper proposes a methodological framework for examining the distributional effects of alternative agricultural policies in less developed economies. The framework combines disaggregated household models with an explicit modelling of the linkages between product and factor markets.

Reply to Brush et al.: Wake-up call for crop conservation science

We strongly concur with Brush et al. (1) regarding the urgency for a new generation of studies (2), but reject claims that our findings are unsupported and our comparisons false, a misperception that could delay adequate academic and policy responses. First, spurious or not, it is not our interpretation that we put to the test but that of influential scholars who, notwithstanding studies’ design and methodological differences, conclude that “there is increasing evidence that small-scale farmers throughout the world, and especially in areas of crop domestication and diversity, continue to maintain a diverse set of crop varieties” (3) and “after thirty years of crop collection and research … the concept of genetic erosion remains more a presumption of what is likely to occur than a demonstrated fact” (4).

Implications of carbon forestry for local livelihoods and leakage

Abstract• ContextAn inequitable distribution of the costs and benefits of carbon forestry could undermine its role in tackling climate change, but safeguarding local livelihoods could undercut its effectiveness.• AimsWe simulate a reforestation program in a densely populated locality in central Mexico to analyze indirect land-use change, or leakage, associated with the program and its implications for local livelihoods.• MethodsAn agent-based, general equilibrium model simulates scenarios that deconstruct the sources of leakage and livelihood outcomes.• ResultsSimulations reveal how conditions linking land, labor, and food markets determine the costs and benefits of reforestation and simultaneously the potential for leakage. Leakage is lowest in remote and poorly integrated localities where declining wages foster local food production while discouraging consumption. Since leakage is tied to consumption, there is a trade-off between the program’s effectiveness and an equitable outcome.• ConclusionAn ideal strategy could target those localities with few remaining forests, where a program might lead to agricultural intensification rather than expanding the agricultural frontier. Alternatively, the scheme could incorporate remaining forests to avoid deforestation while encouraging reforestation. An uneven distribution of costs and benefits, where some stakeholders may draw benefits from others’ losses, could nevertheless set the stage for conflict. Acknowledging these trade-offs should help design a politically feasible program that is effective, efficient, and equitable.