Remote sensing of trophic cascades: multi-temporal landsat imagery reveals vegetation change driven by the removal of an apex predator

Context Trophic cascade theory predicts that predators indirectly benefit plants by limiting herbivore consumption. As humans have removed large predators from most terrestrial ecosystems the effect of their absence is unrecognized. Objectives A manipulation of dingo populations across Australia's dingo-proof fence, within the Strzelecki Desert, was used to assess how predator absence has altered vegetation cover dynamics at landscape and site scales. Methods Landscape-scale analysis used Landsat fractional vegetation cover time series statistics to classify landforms and examine vegetation dynamics either side of the dingo fence. Generalised additive models were used to analyse the influence of predator absence on site-scale observations of fauna abundance and vegetation cover. Results The location of the dingo fence was visible as a change in both the standard deviation and maximum of non-photosynthetic vegetation (NPV) cover (e.g. wood and dry leaves) over 32 years (1988-2020). On average, NPV cover of swales decreased in the standard deviation by 1.4% and in the maximum by 5.0% where dingo abundance was reduced. The differences were consistent with suppressed vegetation growth following rainfall, due to high grazing pressure, where predators were rare. The landscape-scale analysis was supported by site-scale observations. Conclusions The influence of the trophic cascade was observable at both the landscape and site scales, suggesting that apex predator removal has significantly affected the arid ecosystem's responses to resource pulses. Analogous effects may exist across the large areas of the planet over which apex predators have been extirpated.

Automated summary

A study in the Strzelecki Desert in Australia found that the absence of predators has altered vegetation dynamics, with reduced vegetation cover where dingo populations were decreased. The trophic cascade effect was observed at both landscape and site scales, indicating significant impacts of apex predator removal on arid ecosystems.