To plant trees or allow natural regeneration? 

This is the question a lot of people who are restoring habitats will be asking themselves. So here is an article about what Welsh Dee Trust are doing and finding, and the pros and cons of different techniques. 

Most of our habitat restoration sites are in farmland alongside rivers. We are trying to restore the natural processes to the river including the growth of new young trees. 

Usually, this involves fencing to stop livestock grazing a site and allow wildflowers and trees to grow. 

Once the fence is installed, we have two options.  

1. Plant trees  

or 

 2. Allow seeds to disperse and young trees to grow completely on their own. This is called natural regeneration. Which option is best is a surprisingly controversial debate. 

There are advantages to natural regeneration:

  • Locally varied genetic seed and therefore trees
  • Easier as no ongoing management needed
  • Trees can be hardier with higher survival rates 

But, many of our sites have very low or even no regeneration. For example, this site below where we are turning an improved but very wet field into a wet woodland. Two years after removing grazing, and we could not find a single naturally occurring sapling at this site. 

Why has there been no natural regeneration? Thick grass sward stopping growth? Grazed off by escaped sheep or voles? Not enough seed source? Too dry or wet? 

Possibly it just needs more time and two years isn’t enough to allow trees to naturally regenerate. But in the middle of a biodiversity crisis do we have time to wait? This woodland will create a wilder salmon spawning stream. Will the salmon care if the trees are planted? 

We have planted trees in patches on this site. Trees raised from local provenance seed and without plastic guards. The trees have been spaced completely at random. These trees have all survived and are doing well. 

Which leads us into our sites we started on this summer like the one below. A nice buffer that we hope will scrub up with new trees, to create a nice woodland riparian buffer strip with homes for lots of wildlife. 

Do we plant this site with trees? Allow it to naturally regenerate? We will likely plant patches of trees and we will leave some areas to regenerate Another site we have a management plan, ongoing management, and tree guards. It will be interesting to compare all the sites.