During the last century, afforestation and intensification of sheep grazing in the British uplands have led to widespread declines in globally rare heather moorland. We quantified changes in heather cover over 70 years in relation to changes in sheep grazing on Langholm Moor, and examined the impact on red grouse, a gamebird inhabiting heather moorland. Between 1948 and 2009, when grazed heavily by sheep, heather-dominated vegetation declined from 53 to 14% cover. Large-scale sheep reductions from 2011 then allowed increase of heather-dominated vegetation cover to 18% by 2015. However, changes in heather cover were associated with changes in grouse abundance only where heather-dominated cover was reduced below thresholds of 27% (95% CL 18–36%; pre-breeding) and 17% (95% CL 13–20%; post-breeding). The number of grouse shot between 1951 and 1992 remained high where 37–65% of dominant heather cover was retained, but then declined between 1992 and 1996 following increased predation by raptors, leading to the cessation of shooting. Subsequently, grouse densities fluctuated in relation to periodic management by gamekeepers (1992–1999 and 2008–2016), but heather loss continued possibly until 2011, and predation in this context prevented sustained increases sufficient for ‘driven’ shooting. Grouse shooting provides an economic incentive to maintain and restore heather moorland. On Langholm Moor, however, afforestation in the surrounding landscape and isolation from other heather moors may have led to a grouse population less well buffered against growing predation pressure, especially outside keepered periods. As grouse shooting could not be restored, the future management of the moor remains uncertain.

在上个世纪中，英国高地的植树造林和绵羊放牧加剧，导致全球稀有的石南花高沼地普遍减少。我们量化了70年来与在Langholm沼地放牧的绵羊有关的石南花覆盖的变化，并研究了对栖息在石南花高沼地的野鸟红色松鸡的影响。1948年至2009年之间，绵羊放牧时，石南花为主的植被覆盖率从53％下降至14％。从2011年开始大规模减少绵羊数量，到2015年，以石楠为主的植被覆盖率增加到18％。但是，只有在石楠为主的覆盖率降低到27％的阈值以下时，石楠覆盖率的变化才与松鸡丰度的变化相关（95 ％CL 18–36％；繁殖前）和17％（95％CL 13–20％；繁殖后）。在1951年至1992年间，松鸡的射出次数一直很高，保留了37-65％的主要石楠覆盖物，但在猛禽捕食增加后，1992年至1996年间下降了，导致了射杀的停止。随后，松鸡密度随着游戏者的定期管理而波动（1992-1999年和2008-2016年），但石南花的损失可能一直持续到2011年，在这种情况下，掠夺阻止了持续增长，足以实现“主动”射击。松鸡射击是维持和恢复希瑟高地的经济动力。但是，在Langholm沼地，周围景观的绿化和与其他希瑟荒地的隔离可能导致松鸡种群无法更好地抵御日益增加的捕食压力，尤其是在饲养期以外。