Retention time and the functional response of beavers
Retention time and the functional response of beavers
复制标题
海狸的保留时间和功能反应
作者：
J. Fryxell;S. M. Vamosi;R. A. Walton;C. Doucet
我们研究了草料保留时间的种间差异对海狸食物摄入率和能量增益的影响。海狸的随意摄入率是消化道中停留时间的双曲函数和海狸活质量的正线性函数。混合饮食动物的平均保留时间与饮食成分成比例地变化。提供单一特异的颤抖白杨或斑点桤木树苗的海狸的每日摄入率显示出对树苗生物量密度变化的单调减速（2型）功能反应。这两种饲料品种的日摄入量不同，保留时间长的桤木的消耗率低于保留时间短的白杨。当动物以停留时间较长的物种为食时，净能量增益率也会降低。我们的研究结果表明，保留时间的种间差异在决定海狸干物质摄入率和能量增益方面起着重要作用，这可能会影响海狸与植被相互作用的稳定性。
We investigated the effects of interspecific variation in forage retention time on rates of food intake and energy gain by beavers. Ad libitum intake rates by beavers were a hyperbolic function of retention time in the digestive tract and a positive linear function of beaver live mass. Mean retention times of animals on mixed diets varied proportionately with diet composition. Daily intake rates by beavers provided with monospecific stands of trembling aspen or speckled alder saplings showed a monotonically decelerating (type 2) functional response to changes in sapling biomass density. Daily intake rates differed between these two forage species, such that alder with a long retention time produced lower consumption rates than aspen with a short retention time. Net rates of energy gain were also reduced when animals foraged on species with long retention time. Our results suggest that interspecific variation in retention time plays an important role in determining rates of dry matter intake and energy gain by beavers, which could influence the stability of beaver-vegetation interactions.