Using High-Resolution Remotely Sensed Data to Examine the Relationship Between Agriculture and Fertility in Mali

Abstract

Mali reports one of the highest fertility levels in the world. Most Malians grow their own food or rely on locally grown food to feed their families. Because Mali is potentially facing a loss of existing arable land due to climate change, however, concern over the ability of the country to meet the nutritional needs of its growing population is high. Building on historical studies of fertility and agriculture, in this research we examine the impact of local food production on fertility outcomes, taking advantage of geo-referenced health data and recently developed analytic strategies from the remote sensing literature. To examine this relationship we rely on the Demographic and Health Survey data from 2006 as well as on a collection of very high-resolution remotely sensed imagery. Results suggest that fertility, and in some cases fertility aspirations, is positively related to food production and broader scale food production strategies. These results hold even after accounting for individual variation in socioeconomic status.

马里拥有全世界最肥沃的土壤层之一。马里人多半自给自足，抑或仰赖在地生产的食物来养育家庭。但由于气候变迁，马里正可能面临现存的可耕地丧失的危机，因此有着相当多的疑虑，担心该国能否满足成长中的人口营养需求。我们根据肥沃度与农业的历史研究，并善加利用提及地理位置的健康数据，以及晚近遥测文献建立的分析策略，于本研究中检视在地粮食生产对于肥沃度造成的影响。为了检视此般关係，我们倚赖自2006年开始的人口与健康调查数据，以及相当高辨识度的遥测影像集。研究结果指出，肥沃度、以及在某些案例中是肥沃度的渴望，与粮食生产和更大尺度的粮食生产策略正向相关。这些研究结果，即便在考量社经地位的个人变异后，仍然为真。

Malí registra uno de los más altos niveles del mundo en fertilidad. La mayoría de los malianos producen su propio alimento o dependen de alimento producido localmente para alimentar a sus familias. Sin embargo, en cuanto que Malí potencialmente enfrenta la pérdida de tierra arable debido al cambio climático, es alta la preocupación sobre la capacidad del país para satisfacer las necesidades nutricionales de su población en aumento. Elaborando a partir de estudios históricos de fertilidad y agricultura, en esta investigación examinamos el impacto que tiene la producción local de alimentos sobre el comportamiento de la fertilidad, aprovechando los datos de salud georreferenciados y las estrategias analíticas recientemente desarrolladas en la literatura sobre percepción remota. Para examinar esta relación dependemos de datos del Estudio Demográfico y Sanitario de 2006, lo mismo que de una colección de imágenes a muy alta resolución. Los resultados sugieren que la fertilidad, y en algunos casos la aspiración de fertilidad, están positivamente relacionadas con la producción de alimentos y con las estrategias de producción alimentaria a escalas más amplias. Estos resultados se mantienen incluso después de tomar en cuenta la variación individual del estatus socioeconómico.

Key Words:

• fertility, food insecurity, food production, Mali, remote sensing

Palabras clave:

• fertilidad, inseguridad alimentaria, producción de alimentos, Malí, percepción remota

关键词:

• 肥沃度，粮食不安全，粮食生产，马里，遥测。

Notes

1 A population is considered pretransitional when the contraceptive use rate among married women is below 10 percent (Bongaarts 2008). In adopting that definition here the population of Mali is considered pretransitional.

2 A common cited example is that of lactational amenorrhea.

3 These zones are based on zones created by the US AID-funded Famine Early Warning System Network (Fews Net 2010). Detailed descriptions of each livelihood zone can be found on the FEWS.net Web site. Zones are constructed based on local expert knowledge of markets, land use, cultures, and historical trends as well as climate and weather features. We have adapted the zones for our purposes into larger, aggregate zones representing these three dominant lifestyle approaches.

4 Because it is not possible to distinguish between cash crops and food crops with the remotely sensed data, cultivated area as calculated in this analysis refers to both food and cash crops. Although more cultivation is assumed to indicate greater food availability, it could also indicate greater income from cash crops. Not all farmers produce cash crops, but the majority of small-scale cash crop farmers area also engaged in food production. This context of food and cash crop production therefore supports the use of a general measure of cultivation as a measure of food production.

5 NDVI is a commonly used measure within remote sensing to measure the amount of vegetation growth (see Tucker 1979). We use MODIS-based NDVI data based on the NASA Terra satellite (Justice et al. 1998; Huete et al. 2002).

6 It is important to note that variables related to soil quality, market access, and other community sociodemographic characteristics might be highly relevant to the way that locally produced food is used and distributed. Very little of this type of spatial data exists for Mali. Furthermore, many of these types of variables are qualitative in nature (e.g., market access) and cannot be used in a study of diverse communities. In this study, we chose to use quantitative data that are readily available at relatively fine spatial scales. In addition to the variables shown here, we explored the predictive capabilities of slope, compound topographic index, and rainfall anomalies. Analyses not shown here indicated that NDVI, rainfall, and population were significant predictors among the larger suite of variables and are therefore the variables used in this study.

7 In our sample the women identified as pastoralists live within the pastoralist livelihood zone but are likely not strictly pastoralists as the survey data (DHS) are not designed to collect information from nomadic communities.

8 The drops in all three livelihood zones during the summer of 2006 are not actually reflective of decreased birth rates; rather, they are a reflection of the sampling strategy. DHS interviews were conducted over a period of months creating a situation where some summer 2006 births were not counted as the women were interviewed before their children's births.

9 Care needs to be taken in the discussion of conceptions. Given the lack of conception data in the DHS, we assume that a child was conceived nine months prior to the birth month. Given the possibility of early-term births, potentially more likely in the event of food insecurity, a child could have been conceived more recently.

Additional information

Notes on contributors

Kathryn Grace

KATHRYN GRACE is an Assistant Professor in the Department of Geography at the University of Utah, UT 84112-9155. E-mail: [email protected]. Her research interests include population, reproductive health, land use, and food insecurity in the developing world.

Nicholas N. Nagle

NICHOLAS N. NAGLE is an Assistant Professor in the Department of Geography at the University of Tennessee, Knoxville, TN 37996. E-mail: [email protected]. His research interests include the production of small area population data and geospatial data fusion.