Shrub encroachment is linked to extirpation of an apex predator

The abundance of shrubs has increased throughout Earth's arid lands. This ‘shrub encroachment’ has been linked to livestock grazing, fire-suppression and elevated atmospheric CO2 concentrations facilitating shrub recruitment. Apex predators initiate trophic cascades which can influence the abundance of many species across multiple trophic levels within ecosystems. Extirpation of apex predators is linked inextricably to pastoralism, but has not been considered as a factor contributing to shrub encroachment.
Here, we ask if trophic cascades triggered by the extirpation of Australia's largest terrestrial predator, the dingo (Canis dingo), could be a driver of shrub encroachment in the Strzelecki Desert, Australia.
We use aerial photographs spanning a 51-year period to compare shrub cover between areas where dingoes are historically rare and common. We then quantify contemporary patterns of shrub, shrub seedling and mammal abundances, and use structural equation modelling to compare compe...

全球干旱地区的灌木丰度已持续攀升。这种“灌木侵占”现象与家畜放牧、火防控措施以及大气CO₂浓度升高密切相关，而大气CO₂浓度升高可促进灌木定植。顶级捕食者可引发营养级联效应，进而影响生态系统内多个营养级上众多物种的种群丰度。顶级捕食者的灭绝与游牧业有着密不可分的联系，但此前并未被视作导致灌木侵占的影响因素。

本研究旨在探讨：澳大利亚最大陆生捕食者——澳洲野犬（Canis dingo）的灭绝所引发的营养级联效应，是否会成为澳大利亚斯特尔泽莱基沙漠（Strzelecki Desert）灌木侵占的驱动因素。

本研究采用跨度达51年的航空影像，对比历史上野犬种群稀少与常见区域的灌木覆盖度；随后量化当前灌木、灌木幼苗及哺乳动物的丰度格局，并运用结构方程模型（structural equation modelling）对比……