RSPB: Lessons from an advanced soil monitoring system around the Major Oak

Conservation professionals can learn a lot from the RSPB’s embrace of new technologies to manage ancient sites

Deep in the heart of Sherwood Forest, the Major Oak is shrouded in folklore and history. Potentially older than the nation it grows in, this gigantic English oak features prominently in the legends of Robin Hood, serving as the shelter for his outlaw gang.  

Now in terminal decline, the Major Oak is, essentially, receiving hospice care from the Royal Society for the Protection of Birds (RSPB) - but being an organism already many centuries old, it’s hoped that with the right care, the Oak still has many years of life left in it.  

Such care requires a sophisticated monitoring apparatus that harnesses some pretty cutting-edge sensors. To get a sense of the project, EnvirotechOnline sat down with the RSPB’s Estate Operations Manager for Sherwood Forest, Chloe Ryder. 

What is being monitored in Sherwood Forest and how is it being monitored? 

The RSPB is a science and evidence-led organisation, and at Sherwood we monitor many of the reserve’s taxonomic groups. This includes population trends and mapping territories and extents, and measuring them against our work to assess its impact on priority species here. 

One thing we have recently endeavoured to monitor much more closely is the condition of the soil around the roots of the Major Oak. The condition of the soil is linked to a deterioration in its health over recent decades, visible in the crown of the tree, and there is a long-standing obligation to de-compact the soils around it. To assist us, there are a number of data sets we are collecting from the earth around the Major Oak and from the tree itself.  

Some of this is historic data, but soil stations installed in the past few months also now monitor a range of factors in real time. This includes moisture content, pH levels and temperature. They give an indication of nutrient availability, too. The results from the soil stations can be directly linked to the results from the dendrometer devices, installed on the tree in 2024, which monitor growth and shrinkage related to water uptake. 
  
We also obtain data about the chlorophyll content and chemical composition of leaves taken from the canopy of the tree in the summer when it is in ‘peak leaf,’ as well as from soil sampling and DNA extracted from roots and leaves. All of this data is building a bigger picture of the tree’s health from root to leaf. 

Why do these parameters need to be monitored? 

This is vital to give us the most accurate picture of what is happening within and around the tree. It will help to shape any actions and pieces of work we undertake to slow the inevitable decline of this incredible natural icon for as long as we possibly can. With the work that we can do with leading experts in soil condition, tree health and hydrology, we hope to sustain it for many more years to come. 

Is Sherwood Forest unique in monitoring these parameters? 

No, but there is only one Major Oak, and that is why we are doing the work here; it’s vital for the tree’s cultural significance as well as its ecological value, but we are one of a few places where such technology is being used in ancient tree management. In addition, we are working with consultants from across Europe and sharing expertise and knowledge with partners, with the shared objective to protect, conserve and gain enthusiasm for ancient and veteran trees, so they are afforded better protection, which ultimately requires a lot of funding. 

Is this an update to your previous monitoring methods? 

It is an enhancement to previous methods.  

The public affection for the Major Oak has meant that it has undergone interventions since Edwardian times, sometimes with considerable feats of engineering, to sustain it.  All of those interventions have in some way required monitoring for their impact and all have contributed to the condition that it is in now. It has become a scientific microcosm of ancient oak management through the decades. It is exceptionally old, and we know that it is in decline. We therefore want information from as many expert sources as we can to best inform the work that we do, and this means taking opportunities to use ever-evolving technology. 

There has been action to remediate the soils around its roots in the past, but it may not have been fully understood before now how that relates to the tree’s internal biological activity. Some of the monitoring also gives us a much more accurate view of the impact of external factors, such as climate change. There are other aspects we’d like to find out about, but that may require accessing expertise and technology that we are not yet aware of. But all of the things we are doing at the moment give us a better indication of what is happening to the Major Oak and how best we can help it.