Sampling bias exaggerates a textbook example of a trophic cascade.
Understanding trophic cascades in terrestrial wildlife communities is a major challenge because these systems are difficult to sample properly. We show how a tradition of non-random sampling has confounded this understanding in a textbook system (Yellowstone National Park) where carnivore [Canis lup...
| Published in: | Ecology Letters |
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| Main Authors: | , , |
| Format: | Manuscript |
| Language: | English |
| Published: |
Wiley
2022
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| Subjects: | |
| Online Access: | https://doi.org/10.1111/ele.13915 https://pubmed.ncbi.nlm.nih.gov/34748261 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9298920/ |
| Summary: | Understanding trophic cascades in terrestrial wildlife communities is a major challenge because these systems are difficult to sample properly. We show how a tradition of non-random sampling has confounded this understanding in a textbook system (Yellowstone National Park) where carnivore [Canis lupus (wolf)] recovery is associated with a trophic cascade involving changes in herbivore [Cervus canadensis (elk)] behaviour and density that promote plant regeneration. Long-term data indicate a practice of sampling only the tallest young plants overestimated regeneration of overstory aspen (Populus tremuloides) by a factor of 4-7 compared to random sampling because it favoured plants taller than the preferred browsing height of elk and overlooked non-regenerating aspen stands. Random sampling described a trophic cascade, but it was weaker than the one that non-random sampling described. Our findings highlight the critical importance of basic sampling principles (e.g. randomisation) for achieving an accurate understanding of trophic cascades in terrestrial wildlife systems. |
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