Population Dynamics of Small Mammals in Semiarid Ecosystems

Small mammals in semiarid ecosystems exhibit pronounced fluctuations in abundance driven primarily by the interplay of abiotic pulses and biotic interactions. These water-limited landscapes, subject to irregular rainfall and frequent drought, impose strong bottom-up control on rodent populations through episodic food availability. Key demographic parameters—apparent survival, recruitment and realised population growth rate—respond rapidly to precipitation events, particularly those associated with the El Niño–Southern Oscillation. Top-down pressures from predation and asymmetric interspecific competition further modulate these baseline patterns, shaping community composition and richness. Long-term studies employing experimental exclusion grids and capture–mark–recapture approaches across regions such as thorn scrub in Chile and oak woodlands in California have revealed that resource pulses can trigger irruptions in some species while extended dry spells lead to competitive hierarchies and local declines. These dynamic processes influence broader ecosystem functions, including seed dispersal, vegetation regeneration and nutrient cycling. As climate change alters the frequency and intensity of rainfall events, understanding the population dynamics of small mammals in semiarid systems is critical for predicting community resilience, guiding conservation planning and informing adaptive land-management strategies in arid and semi-arid regions worldwide.

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Population Dynamics of Small Mammals in Semiarid Ecosystems publication trend

The graph below shows the total number of articles in population dynamics of small mammals in semiarid ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Population dynamics: Patterns of change in population size and structure over time.

Semiarid ecosystem: A region receiving low and highly variable rainfall, typically between 250 and 500 mm annually.

Capture–mark–recapture: A field method involving the capture, marking and subsequent re-sampling of individuals to estimate demographic rates.

Bottom-up regulation: Control of population processes by resource availability rather than by predation or disease.

Recruitment: The addition of new individuals to a population through birth or immigration.

Apparent survival: The probability that an individual remains alive and within the study area between sampling occasions.

Realised population growth rate (λ): The ratio of population size between consecutive time intervals, incorporating survival and recruitment.

Interspecific competition: Negative interaction between species that vie for the same limited resources.

References

1. Long-term research in Bosque Fray Jorge National Park: Twenty years studying the role of biotic and abiotic factors in a Chilean semiarid scrubland. Revista Chilena de Historia Natural (2010).
2. Multiple coping strategies maintain stability of a small mammal population in a resource‐restricted environment. Ecology and Evolution (2021).
3. Variable interspecific competition under megadrought conditions: rodent population dynamics in semiarid Chile. Oikos (2023).
4. Decline in small mammal species richness in coastal‐central California, 1997–2013. Ecology and Evolution (2023).