Related Experiment Video
Updated: Jun 10, 2026
10:20
Linking Predation Risk, Herbivore Physiological Stress and Microbial Decomposition of Plant Litter
Published on: March 12, 2013
Introduced predators transform subarctic islands from grassland to tundra
D A Croll1, J L Maron, J A Estes
1Department of Ecology and Evolutionary Biology, Island Conservation, University of California-Santa Cruz, Santa Cruz, CA 95060, USA. croll@biology.ucsc.edu
Science (New York, N.Y.)
|March 26, 2005
Summary
Introduction of arctic foxes significantly altered Aleutian island ecosystems. By reducing seabird prey, foxes decreased nutrient transport, impacting soil and transforming plant communities from grasslands to shrublands.
Area of Science:
- Ecology
- Food web dynamics
- Island biogeography
Background:
- Top predators influence prey populations, but their effects on lower trophic levels, especially plant communities, are debated.
- Trophic cascades altering entire plant communities are rare in terrestrial ecosystems.
Purpose of the Study:
- To investigate the impact of introduced arctic foxes (Alopex lagopus) on the Aleutian archipelago's food web and plant communities.
- To elucidate the pathway through which predator-prey interactions affect terrestrial ecosystems.
Main Methods:
- Field observations and ecological surveys in the Aleutian archipelago.
- Analysis of predator-prey relationships, specifically arctic foxes and seabirds.
- Assessment of soil nutrient levels and plant community composition.
Main Results:
- Arctic foxes preyed on seabirds, significantly reducing nutrient transport from marine to terrestrial environments.
- Reduced nutrient input led to decreased soil fertility.
- Plant communities shifted from grassland dominance to dwarf shrub/forb-dominated ecosystems.
Conclusions:
- Introduced arctic foxes created a strong trophic cascade with significant impacts on plant communities.
- Predator-induced alterations in nutrient cycling represent a previously unrecognized pathway affecting terrestrial ecosystems.
- The study highlights the profound indirect effects of top predators on ecosystem structure and function.
Related Concept Videos
00:48Optimal Foraging
How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
01:50Threats to Biodiversity
There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...
02:39Predator-Prey Interactions
Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.Although predation is commonly associated with carnivory, for...
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
02:31Habitat Fragmentation
Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land conversion, as well as slower geological processes leading to changes in the physical environment, are the two leading causes of habitat fragmentation. The fragmentation process typically follows the same steps: perforation, dissection, fragmentation, shrinkage, and attrition.
01:05Instinctive Drift
Instinctive drift refers to the tendency of animals to revert to their innate behaviors despite repeated reinforcement. Breland and Breland demonstrated this concept in an experiment with a raccoon. The raccoon was trained to pick up two coins and place them in a container in exchange for food. Initially, the raccoon learned to associate the coins with food, making them a conditioned stimulus or a substitute for food. However, over time, the raccoon became less willing to put the coins into the...