Figure 1.

Impact, relative to an undisturbed state, of the removal of net primary production (NPP) on the biomass of organisms in different trophic levels—autotrophs (grey), herbivores (green), omnivores (purple) and carnivores (red)—in four ecosystems: (a) high productivity, aseasonal (Uganda); (b) relatively high productivity, highly seasonal (France); (c) relatively low productivity, seasonal (Gobi Desert, China); and (d) low productivity, aseasonal (Libyan Desert). Ecosystems were subjected to levels of NPP removal that increased by 1% per year for between 0 and 90 years, resulting in maximum levels of NPP removal ranging between 0 and 90%. Values shown here are the ecosystem properties after 100 years since the onset of impact. Error bars show ± 95% confidence intervals; open points show levels of impact for which at least one of the time series did not show a significant negative trend (according to a Mann–Kendall test, run using the ‘Kendall’ package Version 2.2⁴⁶ in R Version 3.3.3⁴⁴, P < 0.05). The grey, horizontal dashed line indicates projected values for unimpacted ecosystems. The diagonal dashed line indicates the impact expected if that impact occurred in direct proportion to the amount of plant productivity removed (i.e. y = 100 − x).