DOI: 10.5061/dryad.j6q573nkr
title: Biodiversity and pollination benefits trade off against profit in an intensive farming system

description: Agricultural expansion and intensification have boosted global food
 production but have come at the cost of environmental degradation and
 biodiversity loss. Biodiversity-friendly farming that boosts ecosystem
 services, such as pollination and natural pest control, is widely being
 advocated to maintain and improve agricultural productivity while
 safeguarding biodiversity. A vast body of evidence showing the agronomic
 benefits of enhanced ecosystem service delivery represents important
 incentives to adopt practices enhancing biodiversity. However, the costs
 of biodiversity-friendly management are rarely taken into account and may
 represent a major barrier impeding uptake by farmers. Whether and how
 biodiversity conservation, ecosystem service delivery, and farm profit can
 go hand in hand is unknown. Here we quantify the ecological, agronomic and
 net economic benefits of biodiversity-friendly farming in an intensive
 grassland-sunflower system in southwest France. We found that reducing
 land-use intensity on agricultural grasslands drastically enhances flower
 availability and wild bee diversity, including rare species.
 Biodiversity-friendly management of grasslands furthermore resulted in an
 up to 17% higher revenue on neighboring sunflower fields through positive
 effects on pollination service delivery. However, the opportunity costs of
 reduced grassland forage yields consistently exceeded the economic
 benefits of enhanced sunflower pollination. Our results highlight that
 profitability is often a key constraint hampering adoption of
 biodiversity-based farming and uptake critically depends on society’s
 willingness to pay for associated delivery of public goods such as
 biodiversity.
description: Species richness and abundance data on bees were collected in
 2015 in 21 pairs of grasslands and adjacent sunflower fields in
 southwestern France. In each grassland and sunflower field, bees were
 surveyed in two 150 m<sup>2</sup> transects, with a total of
 15 min net surveying time per transect. Sunflower fields were sampled in
 two survey rounds during sunflower bloom; grasslands were sampled twice
 just before and twice shortly after sunflower bloom.  All entomophilous
 plant species that flowered during the grassland surveys were recorded and
 their flower cover was estimated as the total number of flower units × the
 mean surface area of the flower unit, divided by the transect area. Total
 flower cover per transect was determined as the sum of the cover of all
 observed flowering species. The contribution of insect
 pollination to sunflower crop yield was assessed using pollinator
 exclusion treatments. Prior to anthesis, ten pairs of sunflower plants
 were selected in each field, with the pairs evenly distributed along a 45
 m transect perpendicular to the crop edge. One plant of each pair was
 randomly selected and its flower head was covered with a fine mesh nylon
 bag (&lt;1 mm × 1 mm), allowing self- and wind-pollination but
 excluding insect-pollination. The flower head of the other selected plant
 was not bagged and remained accessible to all flower-visiting insects. All
 bags were removed after sunflower bloom. After harvest, flower heads were
 dried for 72 hours in a ventilated heat chamber at 37°C, and seeds were
 removed from the flower heads using a threshing machine (Criquet, Moulis).
 Full seeds were dried at 80°C for 48 hours. Full seeds were counted and
 weighed using an automatic counter and an electronic balance,
 respectively. Varietal differences in
 pollination-dependency and crop yield were quantified in a pot experiment
 at Wageningen University Experimental Farm (the Netherlands) in the summer
 of 2016. Seeds of the different varieties were grown outdoors under
 ambient conditions in 11 l pots. Plants were drip irrigated and received
 50 kg ha<sup>-1</sup> of nitrogen fertilizer. Five
 experimental randomized blocks were established, with each block
 containing a pair of plants of each variety. Just before anthesis, a
 randomly selected plant of each pair received a pollinator exclusion
 treatment (1 mm x 1mm fine mesh nylon bag), using the same approach as in
 the field study (see above). Pollinator visitation rates on
 open-pollinated plants were monitored for a total of 60 minutes on two
 occasions during sunflower bloom (30 min each). After harvest, flower
 heads were dried for three weeks at 35°C. Seeds were manually extracted
 and sorted. Dry full seeds were counted using a seed counter and weighed
 using an electronic scale. Early 2016 semi-structured
 interviews were used to survey the farmers participating in the study to
 obtain information on characteristics and agronomic practices on the
 sunflower fields and grasslands. Agronomic information obtained included
 sunflower variety, sunflower field size, sunflower total nitrogen
 fertilizer application (organic and inorganic), grassland sowing year
 (age), sown forage plant species, grassland harvesting frequency (number
 of harvests in 2015) and grassland size.