Friday, November 11, 2011

Valuing pollination services to agriculture
Abstract: Crop pollination by animal pollinators is an important ecosystem service for which there is no generally accepted valuation method. Here, we show that two existing valuation methods, previously thought to be unrelated, are each a special case of a more general equation. We then present a new method, termed attributable net income, for valuing insect pollination of crops. The attributable net income method improves upon previous methods in three ways: (1) it subtracts the cost of inputs to crop production from the value of pollination, thereby not attributing the value of these inputs to pollinators; (2) it values only the pollination that would be utilized by the crop plant for fruit production, thereby not valuing pollen deposited in excess of the plants’ requirements; and (3) it can attribute value separately to different pollinator taxa, for example to native vs. managed pollinators. We demonstrate all three methods using a data set on watermelon pollination by native bees and honey bees in New Jersey and Pennsylvania, USA. We discuss the reasons why different methods produce disparate values, and why the attributable net income method most accurately reflects the actual ecosystem service that is being valued, marketable fruit production.

► Multiple methods are currently used to value pollination services, with divergent results.
► We show that these methods are special cases of the same general equation.
► We introduce a new valuation method, which improves on previous methods.
► All methods are demonstrated using the same data set on pollination services to watermelon.
► The reasons why the different methods produce divergent results are discussed.
A replacement value for native bee pollination is what it would cost farmers to rent enough honey bees to replace the pollination currently provided by native bees. We calculated this value by multiplying the area in watermelon production (746 ha)2 by the industry-wide recommended honey bee stocking rate (4.5 hives ha-1; Delaplane and Mayer, 2000) by the annual rental cost of a honey bee hive in the study area ($60-$75 hive-1)7 by the fraction of farms at which native bees alone are fully pollinating the crop (91%). We used the same method to estimate the replacement value of honey bee pollination, substituting the fraction of farms fully pollinated by honey bees (78%) for the fraction fully pollinated by native bees (91%).
The value of native bee pollination based on the replacement value of renting enough honey bee hives to replace native bees is $0.21 million year-1 (range, $0.20 - $0.21 million year-1) and the replacement value of honey bee pollination is $0.18 million year-1 (range, $0.17 - $0.18 million year-1).
The production value method provides a higher estimate. The estimated annual production value of watermelon in New Jersey and Pennsylvania combined (P⋅Y), before subtracting the costs of inputs to production, is $7.64 million year-1. Multiplying this production value by the 62%±5% (SE) of all pollen deposition done by native bees provides an annual value of $4.74±0.38 (SE) million for the pollination service provided by native bees. For honey bees, the corresponding value is $2.90±0.38 (SE) million year-1.... After subtracting the costs of variable inputs to production, the estimated annual net income value (Eq. (4)) of watermelon in New Jersey and Pennsylvania combined is $3.63 million year-1, leading to estimates of $2.25 0.18 (SE) million for the pollination services provided by native bees and $1.38 0.18 (SE) million year-1 for honey bees
The annual attributable net income value of native bee pollination, when native bees are considered primary pollinators (Eq. (5)), is $3.40±0.16 (SE) million year-1. The value of honey bee pollination, when honey bee pollination is valued residually (Eq. (6)), is $0.24± 0.16 (SE) million year-1 (Fig. B.2). When honey bee pollination is valued as primary (Eq. (5)), its value is $3.07±0.25 (SE) million year-1. When native bee pollination is valued residually (Eq. (6)), its value is $0.56±0.25 (SE) million year-1
The cost of renting a single honey bee colony for almond pollination increased from $35 in the early 1990s to $150 in 2007.
A free version of the paper  is currently available at

by Rachael Winfree 1, Brian J. Gross 2 and Claire Kremen 3
1. Department of Entomology, 93 Lipman Dr., Rutgers University, New Brunswick, NJ 08901, USA; Tel.: + 1 848 732 8315.
2. Food and Resource Economics, University of British Columbia, Vancouver, Canada, BC V6T1Z4
3. Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA 94720, USA Ecological Economics via Elsevier Science Direct
Volume 71; 15 November 2011; Pages 80-88
Keywords: Apis mellifera; biodiversity-ecosystem function; ecosystem services; native bee; pollinator; valuation; ecosystem service valuation; wild bee

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