[Pollinator] Why aren't we growing more willows as an abundant source of pollen for bees? (Kevin Lindegaard)

Fri Sep 19 05:05:06 PDT 2014

Hi,

My blog on willows and bees available at :
http://www.crops4energy.co.uk/src-willows-abundant-source-pollen-bees/ got
a couple of responses on the Listserv and I wanted to respond to these.

*1) A number of willows sold in nurseries are non-native species and become*
*pests as they grow with roots attacking sewer pipes or cesspools.  Fallen*
*branches grow on as vegetative clones if they fall into water and are
swept*
*onto wet sand bars and deltas.  This includes our own naturalized, not*
*native, weeping willow (Salix babylonica).*

My article mainly deals with the use of willow grown as an energy crop
planted in dense plantations and managed as short rotation coppice (SRC).
This involves mechanical harvesting every three years. Attached are some
pictures of SRC. The crop is very neat and tidy when managed properly.
Virtually all the varieties used in SRC breeding are shrub varieties or
shrubby trees like S. discolor (not tree willows) so the pollen should be
good. In most situations the land used is away from key services. Land
drains may be affected but this is not a trait of just willow - other crops
like maize and oilseeds also can root deeply and disrupt drains.

*2)  Many willows fail to secrete nectar in bloom.  As you move further*
*north in latitude insect-pollinated willow species or ecotypes are
replaced*
*by wind-pollinated species or ecotypes so no nectar.  Some apiarists
regard*
*willows as emergency pollen resources very early in late winter-spring
when*
*hives become active before most plants are in bloom.*

This is why research is required. Certain willows are very attractive to
bees and breeding programmes can help. SRC willows are being studies at
State University of NY and Cornell. If there is abundant pollen and nectar
at a critical time of year we should be trying to find this. There are not
many silver bullets to deal with the bee issue - but this could be one!

*3)  Do you have enough water to support your willows?  A number of species*
*require saturated soils saturated throughout most of their active growth*
*cycle.  This means they release more water vapor through their leaves
every*
*day increasing ambient humidity.  An oak on a stony hillside loses about*
*140 liters of water vapor through its leaves every day.  A puny, little*
*fragile willow (Salix fragilis) most release 463 liters a day.*

Willows do like water but it's not essential. In the UK SRC is planted on
ex landfill sites that are very wet in winter and dry as a bone in summer.
The yields can be affected when water is scarce but they still grow better
than most other trees. We are also looking at deploying SRC for other
multifunctional benefits. The high water use of willow together with the
coppice nature of the crops make them a cheap way of reducing flooding
impact. If you need a cheap energy crop, flood defence and early pollen
then SRC willows could be really beneficial.

*4)  Messy and short-lived. The faster a tree grows, the faster it dies.*
* Most willows are short lived (<20 years) and you must be prepared to*
*remove dangerous dead wood and rotting-falling trunks during your life*
*time.*

I don't agree with the longevity of willows - certainly they live a lot
longer in the UK. Also, as SRC is designed to be regularly harvested  the
mess issue is not valid.

*5) Out west, willow stems get infested by an invasive insect, the poplar
and willow borer, and often keel over, creating a very messy bush.*

The breeding programme at Cornell will no doubt be testing varieties
robustly against all sorts of pests and diseases. As long as trials are
conducted where this is a problem it should be able to combat this.

I think there is a great deal of potential to get energy and ecosystem
services from willows as SRC. There is so much variation in the genus that
we really should be trying to harness their many attributes. Please see the
email from Jim Cane in Utah which provides a local view on the potential
for willow.

Best wishes, Kevin.

Kevin- you bring to light an overlooked opportunity, and rightly recognize
that willow species vary a good deal in their value (attraction) to bees,
as I have found here in Utah (weeping willow and coyote willow get little
visitation, Scouler’s willow and of course pussywillow attract Apis and all
manner of native bees, incl. specialists.  In general, label info with bees
will only have “Salix” as they are a challenge to ID, but that is what we
need to guide willow species selection.  Here, we provided our Forest
Service with a 3 page review with a promise of collaborative research, then
silence.  I have plated them at our lab to help tide over tree fruit bees
(other than Apis) for years when frosts or mistimed emergence/bloom are
problems.

Nice work!  I hope you get wider attention,

Jim

===============================

James H. Cane

USDA-ARS Pollinating Insect Research Unit

Utah State University, Logan, UT 84322 USA

tel: 435-797-3879   FAX: 435-797-0461

email: Jim.Cane at ars.usda.gov

web page: *http://www.ars.usda.gov/Research/docs.htm?docid=18333
<http://www.ars.usda.gov/Research/docs.htm?docid=18333>*

publications:* http://digitalcommons.usu.edu/piru/
<http://digitalcommons.usu.edu/piru/>*

Gardening for Bees:
http://extension.usu.edu/files/publications/factsheet/plants-pollinators09.pdf

-- 

*Crops for Energy Ltd*

15 Sylvia Avenue, Knowle, Bristol BS3 5BX

Tel: +44 (0)117 9089057 Mobile: +44 (0)7989 333507

E-mail:  kevin at crops4energy.co.uk

*www.crops4energy.co.uk <http://www.crops4energy.co.uk/>*
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