Empirical Evidence of Density- Dependence in Populations of Large Herbivores

摘要: Density‐dependence is a key concept in population dynamics. Here, we review how body mass and demographic parameters vary with density large herbivores. The consider are age‐ sex‐specific reproduction, survival dispersal. As increases, the of herbivores typically declines, affecting individual performance traits such as age first reproduction juvenile survival. We documented density‐dependent variations reproductive rates for many species from Arctic to subtropical zones, both without predation. At high density, trade‐off between growth delays primiparity often increases costs decreasing future success adult females. Density‐dependent preweaning occurs more polytocous than monotocous species, while effects on post‐weaning independent litter size. Responses much less marked survival, may be exaggerated by changes structure. role dispersal dynamics remains uncertain, because very few studies have examined it. For sexually dimorphic found little support higher sensitivity increasing life history males compared females, except young classes. It unclear whether sensitive male female or combination both. Eberhardt's model predicting sequential effect (from survival) was supported 9 10 case studies. In addition, at birth can also lead cohort effects, including direct longterm average adults. Density interact weather, strength years harsh weather. some synchronization plant phenology cycle process timing late gestation function determines density‐dependence influences reproduction. detection made difficult nonlinear relationships sampling variability, lagged responses changes, structure, temporal variation main factors limiting growth. negative feedbacks size performance, hence traits, thus only expected particular ecological contexts most restricted certain age‐specific traits.