The countryside is incredibly valuable in many ways, be it for healthy ecosystems, for cleaner air, for the well-being of those that walk through it, the income of those that work within it, or for the products it creates. Because of this we are careful to ensure we manage the land at Rushmore to optimize the value and preserve it for future generations. To do this we must understand it better, and for this research is key.
Biodiversity and Irregular Silviculture
At Rushmore the forest is managed using a practice known as ‘irregular silviculture’ which essentially relies on the selective removal of trees at certain intervals, which leads to an irregular stand structure as younger trees grow to replace those removed. This contrasts with the practice of ‘clear fell and re-plant’ often seen in commercial forest. By adopting Irregular Silviculture it enabled us to manage the woodland in a way that was profitable, and that we believed was beneficial for biodiversity, however we had no proof that this was the case. It was in fact widely believed that the richest biodiversity was found in coppice or woodland with limited intervention.
In a bid to understand this more clearly a PhD was undertaken at Rushmore into the various woodland management techniques and their respective impacts on biodiversity. The study looked at coppiced woodland (predominantly Hazel Coppice), woodland without any or very limited intervention, and woodland with an ‘irregular’ structure. The abundance and diversity of moths, birds, and bats within these were measured.
The study showed that the diversity of these animals was very high within irregular silviculture stands, and in many instances higher than other management types. For example summer densities of Marsh Tit within irregular stands were found to be twice that of other management types, suggesting that this is an important habitat for this rare bird which has declined by 70% since the 1970’s. Bat and Moth surveys clearly showed a higher diversity of species within irregular woodland. These findings are encouraging and proof that economically viable woodland management can work alongside successful conservation.
Ash Dieback
Ash is a major constituent to Rushmore’s woodland and therefore plays a significant part in the local landscape. Unfortunately, the majority of these trees are now infected with Ash Dieback, or Chalara, although the severity of impact differs from tree to tree. This difference in impact is partly explained by genetic tolerance of certain trees and studied in depth elsewhere. However, this only explains part of the story, as some trees without this genetic trait, also appear to show tolerance.
Therefore a further PhD study commenced a in 2019 into the relationship between the Ash Dieback disease and other environmental factors, early results show the following:
– Smaller trees, particularly when densely packed, are very vulnerable.
– Medium to larger trees in more open stands with an understory are much less affected.
– There appear to be individual trees of all sizes which have significant genetic tolerance.
These findings are invaluable for informing our management practices of Ash into the future, for instance selective harvesting to remove intolerant or retain tolerant individuals will increase stand resilience through natural regeneration over time. Generally Ash in lower densities is less susceptible suggesting that irregular stand structures and mixtures of Ash and other species would be most resilient. Fortunately this is also better for biodiversity as per our recent biodiversity study
.