We document changes in rangeland during a prolonged drought in the arid Karoo. Rangeland in this arid region is species-rich and dominated by a mixture of long-lived succulent and non-succulent shrubs. Ranching has led to the domination of vegetation by less palatable species, and resting does little to restore diversity because most species are long-lived. Between 2015 and 2020, a combination of rising temperatures and low rainfall reduced vegetation cover and grazing potential throughout the Karoo. Mortality varied among species, habitat and with predrought rangeland condition, but appeared independent of size class. Growth form was not a good predictor of drought survival, although vegetation dominated by non-succulent shrub species before the drought was dominated by a succulent shrub species toward the end of the drought. Dieback was greater on deep soil than in drainage lines and on stony rises. Historically degraded landscapes lost relatively more vegetation cover and grazing capacity than areas protected from grazing. By reducing dominant, long-lived, non-forage shrub species, drought appears to be changing the composition of the vegetation to a state that may have higher grazing potential, particularly if livestock numbers are reduced and reseeding is carried out during the recovery period.

我们记录了干旱的卡鲁地区长期干旱期间牧场的变化。这个干旱地区的牧场物种丰富，以长寿的肉质和非肉质灌木为主。牧场导致植被被不太适口的物种占据，而休息对于恢复多样性几乎没有作用，因为大多数物种都是长寿的。2015 年至 2020 年间，气温上升和降雨量减少导致整个卡鲁地区的植被覆盖和放牧潜力减少。死亡率因物种、栖息地和干旱前牧场条件而异，但似乎与大小等级无关。尽管在干旱之前植被以非多汁灌木物种为主，但在干旱结束时以多汁灌木物种为主，但生长形式并不能很好地预测干旱生存。深层土壤上的顶枯病比排水管道和石丘上的顶枯病更严重。历史上退化的景观比不受放牧保护的地区损失了相对更多的植被覆盖和放牧能力。通过减少主要的、长寿的、非饲料灌木物种，干旱似乎正在改变植被的组成，使其达到可能具有更高放牧潜力的状态，特别是如果牲畜数量减少并在恢复期间进行重新播种。