Top-down and bottom-up forces explain patch utilization by two deer species and forest recruitment

Area of Science:

• Ecology
• Wildlife Management
• Forestry

Background:

• Ungulates significantly influence temperate ecosystems through selective herbivory, affecting vegetation composition and landscape heterogeneity.
• Animal foraging behavior is driven by balancing energy intake with the costs of predation and resource exploitation.
• Deer herbivory can either enhance landscape diversity through disturbance or reduce it via overbrowsing.

Purpose of the Study:

• To investigate how bottom-up (vegetation quality/structure), top-down (hunting, proximity to human settlements, forest edges), and deer-specific factors (feeding type, abundance) influence patch selection in temperate forests.
• To assess the impact of deer patch utilization and light availability on forest regeneration.
• To compare the foraging ecology of a browser (C. capreolus) and a mixed feeder (C. elaphus).

Main Methods:

• Paired camera traps with vegetation sub-plots across ten diverse forest sites in the Netherlands.
• Quantified deer abundance, landscape heterogeneity, and vegetation characteristics.
• Analyzed patch utilization patterns in relation to environmental and species-specific variables.

Main Results:

• Patch utilization by deer was simultaneously influenced by vegetation quality, predation risk, and deer abundance, supporting the safety-in-numbers hypothesis.
• The relative importance of these factors varied significantly between the two studied deer species.
• Increased patch utilization correlated with intensified browsing, reduced tree species diversity, and a shift in forest composition towards dominance by conifers.

Conclusions:

• Two sympatric deer species with different feeding strategies differentially interact with and modify their forest environment.
• Deer herbivory significantly alters forest structure and composition, with implications for biodiversity and ecosystem function.
• Understanding species-specific foraging behavior is crucial for effective wildlife and forest management in temperate ecosystems.