Invasive alien plants negatively impact ecosystems, but recovery of native vegetation may fail following standard methods of alien species removal alone. Alternative management actions may thus be required. Cape Flats Sand Fynbos is a critically endangered vegetation type in the Cape Floristic Region of South Africa which is threatened by Acacia saligna invasion, but standard clearing methods have failed to restore native vegetation structure. A restoration study was performed comparing passive treatments i.e. clearing without burning (stack-block) versus clearing and burning (burn-block), as well as active intervention by sowing seeds of native species, either initially after burning or a year later, in which seeds were either not pre-treated or pre-treated with smoke and heat exposure before sowing. After two years all treatments resulted in different recovery trajectories, although none resembled the reference condition. Clearing without burning facilitated recovery in less degraded areas with higher initial native shrub cover, but otherwise resulted in limited vegetation recovery. Limited recovery facilitated secondary invasion by herbaceous weeds. Active seed sowing resulted in the highest recovery of native shrub cover and diversity. These findings suggest that passive restoration is constrained by seed limitation, due to the lack of recovery of vegetation components under passive clearing treatment. Active sowing was able to partially overcome this constraint through improved recovery of total shrub cover. However, non-sprouting shrub cover was higher while resprouting shrubs and species of Restionaceae were lower compared to the reference condition. Pre-treatment of seeds before sowing improved establishment of some species. Active treatment involving sowing pre-treated seeds after clearing and burning therefore resulted in best fynbos recovery compared to either of the passive treatments tested. A decision tree has been developed based on these findings in order to guide best protocol for managers.

外来入侵植物对生态系统造成负面影响，但仅按照标准的外来物种清除方法，本地植被的恢复可能会失败。因此可能需要其他管理措施。Cape Flats Sand Fynbos是南非开普植物区的一种极度濒危的植被类型，受到刺槐树的威胁入侵，但标准的清除方法未能恢复天然植被结构。进行了一项恢复研究，比较了被动处理，即不燃烧就清除（堆砌块）与清除并燃烧（焚烧块），以及通过在播种后或一年后播种本地物种的种子进行的主动干预。播种前不对种子进行预处理或烟熏和热暴露预处理。两年后，所有治疗均导致不同的恢复轨迹，尽管没有一个类似于参考条件。清除不燃烧不易促进退化程度较低的地区的原始灌木覆盖率较高，但导致植被恢复有限。有限的恢复促进了草本杂草的二次入侵。主动播种可最大程度地恢复天然灌木的覆盖度和多样性。这些发现表明，由于在被动清除处理下缺乏植被成分的恢复，被动恢复受到种子限制的限制。主动播种能够通过改善总灌木覆盖率来部分克服这一限制。但是，与参考条件相比，非萌芽灌木的覆盖率更高，而重生灌木的灌木和毛虫科的物种更低。播种前对种子进行预处理可以改善某些物种的建立。因此，与清除和燃烧后的任何一种被动处理相比，在清除和燃烧后播种经过预处理的种子的主动处理可产生最佳的股指恢复。