Here's the thing.
There are a lot of woodland margins and so on getting fenced off from livestock under environmental schemes. The theory being that the livestock eat the understory and by excluding them the habitat becomes more diverse and supports a greater variety of flora and fauna.
Sounds great, but a lot of such ground near me is becoming choked with bracken. Environmental schemes do not think bracken is a good idea, and neither does anyone else. However, on steep, craggy and/or wooded slopes it is nigh-on impossible to control the bracken once it gets a hold.
There are two problems with the bracken. Firstly, it chokes everything, resulting in the habitat becoming less diverse and supporting a lesser variety of flora and fauna. Secondly, bracken is a really great environment for ticks to multiply and spread. Deer ticks can carry Lyme Disease, which affects humans, and sheep and deer ticks can spread a variety of diseases to dogs and livestock.
Our vet and others are reporting an increase in tick-borne diseases in sheep.