Thrushes Nesting in Pollarded Poplar Trees at the BGI Demonstrator Hub

01 May 2024

While performing a routine morning fence inspection for Biomass Connect here at the BGI Demonstrator Hub, an unexpected sight caught my attention – a bird gliding low towards the pollarded poplar trees. Upon closer examination, I discovered a nest perched atop a tree pointed after pollarding in 2020. This discovery sparked a conversation with colleagues from BGI about the significant implications it has for managing poplar trees in biomass contexts.
 
In the realm of traditional tree management, pollarding stands out as a notable technique characterised by the removal of upper branches to stimulate a robust regrowth of foliage and limbs. This method is particularly beneficial for poplar trees within biomass plantations, enhancing sustainable wood harvesting through the vigorous rejuvenation of trees from a specific cut point. As a renewable source of biomass for energy production, pollarding underpins ecological stewardship by:
  • Facilitating disease management through the removal of possibly infected or pest-afflicted branches.
  • Maintaining trees at a manageable height for straightforward harvesting and lessened storm damage risk.
  • Fostering a dense canopy that improves photosynthesis efficiency and accelerates biomass accumulation.
 
Pollarding at a height of 2 meters, while allowing all sprouts to flourish, appears to create an ideal, secure habitat for song thrushes and their offspring. Contrastingly, other pollarding techniques, such as cutting the tree at its base, do not offer the same benefit. At this level, a bird is unlikely to nest, and the new shoots are at risk of being damaged by rabbits, deer, and hares. Similarly, allowing only one shoot to grow does not facilitate a nesting environment for birds.
 
Given these observations, it becomes clear that a comprehensive study is warranted. Such research would compare the biomass yield from different pollarding methods—cutting at the base, pollarding at 2 meters while leaving a single stem, and considering ecological impacts—on biomass production practices. This investigation would champion a more integrative approach to agriculture, one that equally prioritises yield optimisation and biodiversity conservation, ensuring that biomass production aligns with ecological health and sustainability.
 
Candice Hunt, Bio Global Industries

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