Choice of apple tree affects orchard biodiversity, researchers find

Moss on an apple tree

PLANTING trees producing pie filling favourite the Bramley apple is better for orchard biodiversity than other counterparts, a university study has found.

Researchers showed that beyond the local growing conditions the choice of variety of fruit crop sown has itself a large bearing on the number and type of epiphytes - plants that grow harmlessly on other plants - colonizing the trunk and branches.

It means anyone planting an orchard where the crop is not the main concern can have a positive influence on biodiversity by selecting strains proven to sustain larger numbers of mosses and liverworts.

The Manchester Metropolitan University-led study was carried out in collaboration with citizen scientist and expert on bryophytes, or non-vascular plants, Robin Stevenson.

New research

Dr Jennifer Rowntree, Senior Lecturer in Ecological Genetics and Applied Conservation at Manchester Metropolitan University, said: "There's been a reasonable amount of research that traditional orchards are good for biodiversity and we wanted to look at whether the same could be said for productive orchards.

"The answer is the choice of tree, or cultivar, can have an impact on the associated biodiversity that you find.

"Location has a big effect on biodiversity richness but we could still notice an effect by the type of tree.

"It feeds into the sustainable management of agriculture.”

East Anglian orchards

Trees at five managed orchards in East Anglia, including a pair on the royal Sandringham Estate, were studied over the course of five years by the University’s researchers along with citizen scientist and bryophyte expert Robin Stevenson.

Each orchard had been standing for between 20 and 60 years and their commercially-minded nature means pesticides and fungicides were in use along with mechanical feeding, pruning and harvesting techniques.

Dr Rowntree said: "If you planted, for example, Bramley apple trees you might encourage a large number of epiphytes but if you plant a Howgate Wonder tree you'd wouldn't get very much, it would be a barren tree and pretty much all you would have would be apples.

"It is important because mosses and liverworts further encourage biodiversity in two ways.

"They regulate water and water run off - they are small but act a bit like a sponge and if there's water they soak it up and if it's dry they release it - and they provide a habitat for other insects and invertebrates."

Fortune finds favour

Dr Rowntree and her colleagues found the Fortune variety of apple hosted on average 11 different species of epiphytes per tree, the Cox a mean of 10, and Bramley about eight.

But the Grenadiers had just six species per tree and the Howgate Wonder averaged barely even one.

Dr Rowntree said: "The extent of the variation was not what we expected.

"We think one of the reasons is down to the chemistry, the pH and the texture of the tree bark.

"The survey was originally conducted as a piece of consultancy work where the people undertaking the survey were just looking for epiphytes.

"This was an unexpected finding and we have taken it a bit further.

"The research had a good response at the British Ecological Society conference and people seem to be quite interested in it."

Journal paper

The research paper was published in the February issue of the Ecology and Evolution journal.

Research paper co-author Dr Chantel Davies from consultancy firm Growing Research International said: “Future food security is high on the international agenda, but we need an agricultural system that is sustainable in the long-term.

“Our research shows that biodiversity and productivity do not need to be exclusive, but that we can chose plants not only for the food they provide, but also for the biodiversity that they support."