4. Results and discussion

Using the bio-economic approach, we estimate the economic value of pollination (EVP), the crop vulnerability ratio (CVR), and pollination's contribution to total farm gate value (PCV) for Ethiopia using the 2003–2013 zonal level production value data for 38 different type of crops. We calculate the annual mean value estimates of EVP, CVR, and PCV between 68 and 73 zones of the respective years from 2003 to 2013. For Ethiopia, the mean economic value of pollination, total farm gate value, and economic value of crops under study for the period of 2003–2013

<sup>2</sup> The Food and Agriculture Organization of the United Nations (FAO's), Global Action on Pollination Services for Sustainable Agriculture. http://www.fao.org/pollination/pollination-database.

Figure 1. Crop vulnerability ratio (CVR) (%) for the period of 2003–2013.

Figure 2.

Pollination contribution for farm gate value (PCV) (%) for the period of 2003–2013.

Figure 3.

Total farm gate value, farm gate value of crops under study and economic value of pollination in million USD for the period of 2003–2013.

were >US\$81.3 million, >US\$12.8 billion, and >US\$6.41 billion, respectively. Our estimated crop vulnerability ratio indicates a potential production value loss for the crops studied of roughly 8.4% in the absence of pollinators. The CVR for the period of 2003–2013 is presented in Figure 1 and it ranges between 6 and 13% which is comparable with [13] that showed the national dependency of the agricultural GDP

#### Figure 4.

Crop vulnerability ratio (CVR) (%) per crop category for the period of 2003–2013.

on pollination in east Africa (including Ethiopia) which ranges between 5 and 7.5%. The mean PCV value indicated that the potential relative agricultural sector production value loss attributable to lack of or disappearance of pollinators in Ethiopia was 4.2% and the PCV values for respected year are presented in Figure 2. The highest value of CVR and PCV was found for the year 2007. Total farm gate values and economic value of pollination are presented in Figure 3. The CVR and PCV analyses have been done for different crop categories; fruits had highest CVR values due to their high pollination dependency followed by cash crops (e.g., coffee) and

Figure 6. Ethiopia zone level mapping of the crop vulnerability ratio (CVR) (%) for the period of 2003–2013.

oil seeds (Figure 4). Alternatively, the pollination contribution to farm gate value indicated the highest percentage for oil seeds followed by relatively in similar pattern for fruits and pulses (Figure 5).

Our geographic information system (GIS) analysis revealed the spatial variation of the crop vulnerability ratio (Figure 6), the economic value of pollination (Figure 7), and the pollination's contribution to total farm gate value

Figure 7.

Ethiopia zone level mapping of the economic value of pollination (EVP) in million USD for the period of 2003–2013.

Figure 8.

Ethiopia zone level mapping of the pollination contribution to total farm gate value (PCV) (%) for the period of 2003–2013.

(Figure 8). Zones with the higher CVR values appear to be clustered in the west-central part of the country. The north-western part of the country revealed the highest CVR value; these areas mainly produce oil seed products for export market. Some parts of the south and eastern zones show the lowest CVR value because these areas are dry land and mainly livestock production zones rather than crop production. The result for the spatial pattern of the economic value of pollination shown that it is comparable for most parts of the north-eastern and the south-western parts of the country while it had a highest value in the north-western and the central parts of the country which predominantly produced oil seeds and cash crops.

Providing an estimate and spatial variation of the economic value of pollination is vital for cost-benefit analysis of planned interventions to perceived or anticipated pollinator decline [1]. The spatial analysis of our estimates revealed discrete patterns of zonal variation in pollination services and values within Ethiopia. Spatially explicit analysis of these indicators is important to support policies related to protection of abundant pollination sites for maintaining pollination services. Our results have policy and management implications on the potential benefit of addressing pollinator decline at local level. Similar to the findings of Barfield et al. [1], estimates and spatial analyses of pollination values and vulnerabilities provide information that is useful for the selection of the most appropriate pollinator management strategies at different institutional and ecological scales.
