Forest Garden Skill Share, January 2017

Big thanks to everyone who came to our first Skillshare on 21st January 2017. It was an unexpectedly good turnout in the winter sun. Kudos and gratitude to all who shared ideas and projects, to Chris for leading the warm-up, and to Jo for giving a fascinating account of some recent research into the benefits of agroforestry in European climates.

Research #1 - June 2016

Do European agroforestry systems enhance biodiversity and ecosystem services? A meta-analysis

Yes they do! “Results reveals an overall positive effect of agroforestry (effect size = 0.454, p<0.01) over conventional agriculture and forestry.” (p.149) An effect size of 0.01 is statistically significant. If it's 0.3 it's considered medium and 0.5 is large.

Here's a table showing this.

Other points

  • The studies they looked at ended up mostly being in the Mediterranean (59%) and most were silvopastoral (61%). Silvopasture is the combination of cropping trees and natural meadow which can be fodder for grazing animals.

  • Benefits of agroforestry include: “increased land productivity as the combination of tree and crop systems leads to a more efficient capture of resources (such as solar radiation or water) than separated tree or crop systems (Cannell et al., 1996; Graves et al., 2007; Jose 2009). […] Agroforestry has also been found to improve regulating ecosystem services such as nutrient retention, erosion control, carbon sequestration, pollination, pest control and fire risk reduction, and cultural services such as increase in recreational, aesthetic, and cultural heritage values.” (p151)

  • Notable ecosytem benefit – preventing soil erosion – particularly in Mediterranean countries. One of their recommendations to policy makers was “integrating cover crops and/or grazed legumes in vineyards and olive monoculture plantations generally increases soil fertility and nutrient retention whilst reducing soil loss.” p159

  • Key biodiversity benefit – on bird populations.

  • They flagged up a study which showed that “agroforestry can increase overall yields by up to 40% relative to monoculture arable and woodland systems.” (p156) Graves et al (2007). This sounded amazing so further research was done on this – see below.

  • They also highlighted a study which estimated that agroforestry was sequestering 2.2 Pg of Carbon above and below ground, over 50 years. A Pg is a Petagram or 1012 kg. Lorenz and Lal (2014)

Research #2 – September 2007

Development and application of bio-economic modelling to compare silvoarable, arable and forestry systems in three European countries.

This study was looking at potential sites in Spain, France and the Netherlands to see how much more productive polycultures would be. They used a model called Yield-SAFE to measure yields on things such as pine trees underplanted with annual grains. They did find massively higher yields but given that it's just a model, it seems likely that the actual gain would be lower, especially since there seems to be no account made for the effect of annual tillage on the trees. I will contact the main report author, A R Graves, so see what they say about this.

Contact details for the lovely gardeners who spoke about their projects:

And finally, some upcoming dates for your diary:

The next Skillshare dates have been set! for April 15th, July 8th, and October 21st.

We are quietly excited that Tomas Remiarz has agreed to present an interactive workshop during our October session, alongside a visual exhibition based on his new book Forest Gardening In Practice . There will be more info on this and all the future sessions to follow.

In the meantime, if you have any questions or would like to be involved, please call 07804 596645  /  07733 330379, or email: forestcollectiv@gmail.com. Or just pop over and join us for a cup of hot forest garden tea on any of our Friday or monthly Saturday sessions.

Look forward to see you there!

Vanessa, Jo and all at Edible Landscapes