Pollinators.ie - Hedgerow Management

Allow some of the mixed hedging to flower for pollinators

I’ve been reading a load of interesting information about pollinators this week. I have found the www.pollinators.ie website very informative where it goes into detail about the the All-Ireland Pollinator Plan. The plan addresses pollinator decline and was officially launched in September 2015 in collaboration between The National Biodiversity Data Centre and the Heritage Council. 

  

All-Ireland Pollinator Plan

One third of our bee species are threatened with extinction from Ireland. This is because we have drastically reduced the amount of food (flowers) and safe nesting sites in our landscapes. The All-Ireland Pollinator Plan is about all of us, from farmers to local authorities, to schools, gardeners and businesses, coming together to try to create an Ireland where pollinators can survive and thrive. Buncrana has a lot of places on the interactive map on the website and the community gardens in Carndonagh are on there too. I’ve chosen a specific topic to highlight from their Resources pages which is something most of us, especially farmers can contribute to, the safe care of our hedgerows.

Hedgerows for Pollinators

What is pollination and why is it so important?

Pollination is a vital action in nature; it is the means by which plants fertilise each other in order to produce viable seed to keep the species going.

In some plants pollen is spread by wind, others require the actions of insects to transfer the pollen from the male to the female flower. These insects (honeybees, bumblebees, solitary bees, hoverflies and others) are known as pollinators.  In general trees and shrubs that produce blossom (whitethorn, blackthorn, cherry, crab apple, etc.) are insect pollinated and those that produce catkins (hazel, alder, birch, oak, poplar) are wind-pollinated. The exception is the ‘pussy’ willow which produces an insect pollinated catkin. The blossoming species are often the woodland-edge species and so are the ones most commonly found in hedgerows.

Pollinators are a link in the chain of living (eco) systems that enable life to continue on earth. 

Healthy ecosystems (and therefore healthy pollinator populations) are essential for sustainable agricultural production.

How do hedgerows support pollinators?

Good quality hedgerows provide the four essential needs of pollinators:

•Sources of pollen and nectar for food

•Places to breed

•Places to overwinter

•Corridors and pathways to travel across the landscape

Most agricultural crops that require pollinators only provide a food source for a few weeks – diverse hedgerows and flower-rich verges can provide food over a much longer period to fill the hungry gaps.

What makes a good quality hedgerow for pollinators?

Food Source

Trees, shrubs and wild flowers in hedgerows provide food throughout the season from spring to autumn. Dandelion, blackthorn and pussy willow are very valuable in the spring when little other food is available. Mature whitethorn provides a good source of food later in the spring, followed by elder. Later in the season ivy provides a critical food supply. 

Places to breed and overwinter

Open fields provide few opportunities for bumblebees to nest but hollows and holes in hedge banks along with tussocky grass in hedge margins are ideal. The hollow stems of dead brambles provide nesting and over-wintering sites for cavity nesting solitary bees. Hedgerows that have sandy, earth, or earth and stone banks provide ideal nesting and over-wintering sites for mining solitary bees, particularly if they are south facing.

Corridors

When moving between their nest and feeding sites most pollinators like to follow linear features like hedgerows which give them some protection from the wind and rain. Hedgerows and other linear landscape features in agricultural landscapes can increase the connectivity between otherwise isolated plant and pollinator populations so well-connected networks of hedgerows are important to increase pollinator movement and pollen transfer.  

Hedgerow Management

Hedgerow management for pollinators needs to be considered as part of the wider context of other management objectives – stock control, shelter, screening, etc.

New hedgerows for Pollinators

Planting a diverse range of species is key

Many common and uncommon hedgerow species will provide food for pollinators.  Some native hedgerow species that are insect-pollinated this can be affected by a number of factors such as local climate and altitude. Blackthorn, Wild Cherry, Crab apple, Rowan ,Whitebeam Spindle, Whitethorn/Hawthorn Guelder Rose and Elder are some of the more well known varieties.

Shrubs like gorse and climbers like wild rose, honeysuckle and brambles also provide food and habitat for pollinators.  Hedgerow species need to be suitable for their environment (soil and climate) and complementary to each other – in some situations some species can become dominant and push out less vigorous species. Try and select a suitable mix that will provide blossom throughout the season.  

Ensure good connectivity between hedgerows and other natural and semi-natural habitats

If you can link in your new hedge with other natural and semi-natural habitats in your area then this will make it easier for pollinators to get to and from your new hedge safely and will complement the general ecology of the area. Remember that areas of scrub are also important sources of food for pollinators.

The brochure continues with advice about connecting hedgerows and managing existing hedgerows  for pollinators stressing that over management of the hedgerows by advising about timing and repairing hedges. 

For more on the subject and other advice check out the Pollinators.ie website