Stop that bracken
When bracken grows in the kind of soil conditions it loves, it becomes a highly invasive species. To stop it thriving at the expense of other flora, it's necessary to control its growth. This can be done in a number of different ways, from chemical treatment to mechanical cutting. The sites that the braken thrive on are Sites of Special Scientific Interest (SSSI), so cutting the bracken back protects existing flora and fauna. It weakens its underground energy store (which is also known as its rhizome) meaning that the following years growth is weaker and smaller allowing more space for the more delicate wildflower populations.
Don't forget to rake
If the cut-back bracken wasn't raked away, it would decompose in-situ, adding nutrients to the soil (just like a garden compost). The habitat conditions the rangers are attempting to create are low-nutrient. This is beneficial to a wider diversity of flowering plant species; if the soil was high in nutrients, a few dominate plants would flourish instead. A trip back in the spring will show the fruits of our labours with a fantastic show of spring flowers. A good deal of effort is required to strip the nutrients from the cliffs by raking the bracken cuttings away and removing them from site - a good day's work by the team.