Florian Hartig

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Human and apex predators shape lower trophic levels through top-down control

Ye Htet Lwin, Rui-Chang Quan, Florian Hartig, Hjalmar S. Kühl & Marco Heurich

Biological Conservation, 310, 111352 (2025)
Cite this
@article{lwin2025human,
  author = {Ye Htet Lwin and Rui-Chang Quan and Florian Hartig and Hjalmar S. Kühl and Marco Heurich},
  title = {Human and apex predators shape lower trophic levels through top-down control},
  journal = {Biological Conservation},
  volume = {310},
  pages = {111352},
  year = {2025},
  doi = {10.1016/j.biocon.2025.111352},
}

DOI: 10.1016/j.biocon.2025.111352
Citation statistics: 5 (Google Scholar) · 1 (OpenAlex), as of 29 October 2026

Google Scholar citations per year, as of 17 October 2026 (yearly counts are fetched separately from the total)

Funding

This study was supported through funding by CAS-SEABRI (Y4ZK111B01); National Natural Science Foundation of China (32361143867); Yunnan Province Science and Technology Department (202203AP140007); Transboundary Cooperation on Biodiversity Research and Conservation in Gaoligong Mountains (E1ZK251); Deutscher Akademischer Austauschdienst (DAAD), Research Grants - Doctoral Programmes in Germany, 2022/23 (57588370).

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Abstract

Apex predators are thought to regulate ecosystems through top-down control, but the extent of their impact often varies, potentially due to differences in their abundance and other aspects of the ecosystem, including human disturbances. Here, we analyzed three years of data collected from 114 camera traps placed in Htamanthi Wildlife Sanctuary, northwestern Myanmar. Using multigroup piecewise structural equation modeling, we explored associations among multiple trophic levels, including humans, apex predators, mesopredators, prey species and vegetation across varying apex predator biomass levels within similar environments. We found that variation in apex predator biomass significantly influences trophic associations, especially concerning top-down control exerted by humans and apex predators. Human disturbances had a regulatory role on apex predators and large prey populations and alter their behavior. Apex predators both suppressed and facilitated prey populations, underscoring the crucial role of sustaining apex predator populations in ecosystems. Furthermore, our study highlights positive associations between mesopredators and prey species, demonstrating their coexistence within the ecosystem. Bottom-up effects from vegetation were weaker than top-down processes. Nevertheless, the observed positive link between vegetation and small prey suggests that this bottom-up component also plays an important role in the trophic network. Our study highlights the complex associations between different trophic levels and underscores the importance of considering multiple species for effective conservation and ecosystem stability.

What the paper shows and why it matters

(AI-generated)

Classic ecological ideas describe apex predators, the top carnivores of a food web, as regulators from above: if they decline, mid-sized predators and plant-eaters are expected to increase (the mesopredator release idea) and plants to suffer (the “green world” idea). How strongly this control works varies between systems, possibly with predator numbers and with human disturbance. However, how these ideas play out in real, multi-species food webs is not well understood, nor is the role of humans when they act as “super predators” (Darimont et al. 2015). The paper asks how humans and apex predators together shape the lower levels of such a food web.

The paper argues that in a tropical forest food web, top-down control of the lower levels comes from humans as well as from apex predators, and suggests that human pressure weakens the predators’ own regulatory role. The evidence is camera-trap records from 114 sites in Htamanthi Wildlife Sanctuary, Myanmar. The study compares two nearby areas with higher and lower apex-predator biomass and fits a statistical model of associations (not experiments) among humans, three size classes of predators, prey groups and vegetation. In the area with more apex predators, human disturbance was negatively associated with apex predators and with large prey. Apex predators themselves showed mixed associations: negative with small predators and with semi-arboreal prey (animals such as primates that use both ground and trees), but positive with medium-sized predators and absent for large prey, against the expectation from these ideas. Associations among the lower levels were mostly positive, and vegetation was linked only to small prey, so effects from the bottom of the food web (plants on animals) appeared weaker than control from above.

Figure 3. The multigroup piecewise structural equation model of trophic association in Htamanthi wildlife sanctuary (Fisher’s C = 4.561, df = 2, p = 0.102, AIC = 98.561). From Lwin et al. (2025), Biological Conservation, licensed under CC BY 4.0. Click the image to enlarge.

The study reads these results as showing that protecting and restoring apex predators is not enough to keep a food web in balance unless human pressure is reduced as well, and that conservation should aim at whole communities of species rather than charismatic species alone. The paper acknowledges limits of its evidence: imperfect detection of species by the cameras is not modelled, species are grouped, vegetation is represented by rough proxies, and the results did not fully match its initial predictions. The associations come from observational camera-trap data in one sanctuary.

References