[Closed] why exactly is brechfa closed?

http://mbwales.com/en/content/cms/bases/brechfa/brechfa.aspx

"The Derwen Blue, Green and the Raven Black routes will close on the 1st September 2011 until the 1st December 2011 due to harvesting operations. We apologise for any inconvenience this may cause.

The Gorlech Red will be open.
The safety of our visitors is paramount and at no time is this more important than during forest operations, which are a necessary part of managing the forest to ensure we have sustainable and resilient woodlands which offer a top quality visitor experience.
An announcement was carried on the FC Wales website two weeks prior to the closure, and signs were also placed at the trail entrances. However, we understand the concern of local businesses and trail users regarding this notification period and apologise for any inconvenience.
In future, we will endeavour to give six weeks notice of any closures and, in the meantime, would like to hear from any interested parties to ensure we are able to alert all stakeholders who may be affected.
We would point out that the trails have to be closed every year at about this time - when the holiday period is over - for maintenance work to preserve the quality of the trails.
Any disruption, therefore, will be kept to a minimum as this essential work dovetails with the harvesting operations, the revenue from which contributes to the upkeep of the trails."