ABSTRACT

Increased snow cover and attenuation of light due to shrub expansion can lead to changes in the quantity and nutritional quality of food resources for migratory caribou (Rangifer tarandus). To determine how vegetation is affected by snow accumulation and shade, we conducted an experiment that simulated the light and snow conditions created by increased shrub cover at Deception Bay (Nunavik, Canada), within the summer range of the Rivière-aux-Feuilles caribou herd. We estimated the foliar biomass of two major components of the caribou diet (Betula glandulosa and Carex spp.). We also harvested foliar tissue to conduct chemical composition analyses (nitrogen, fibre, total phenolics). Experimental light attenuation was found to increase the nitrogen concentrations in B. glandulosa and Carex spp. throughout the growing season. Phenolic concentration in B. glandulosa decreased in early summer but was otherwise consistent in response to light attenuation and increased snow cover. Increased snow cover combined with ambient light had a positive effect on the foliar biomass of B. glandulosa. Increased snow cover and shade caused by shrub densification may therefore increase forage quantity and quality for caribou. We suggest investigating the effects of shrub expansion on other components of the caribou diet, such as lichens and forbs.

摘要

由于灌木扩张导致积雪增加和光照减弱会导致迁徙驯鹿 ( Rangifer tarandus )食物资源的数量和营养质量发生变化。为了确定积雪和遮荫如何影响植被，我们进行了一项实验，该实验模拟了 Rivière-aux-Feuilles 驯鹿群夏季范围内欺骗湾（加拿大努纳维克）灌木覆盖增加所产生的光和雪条件. 我们估计了驯鹿饮食的两个主要成分（桦树和苔草）的叶生物量属）。我们还收获了叶组织以进行化学成分分析（氮、纤维、总酚）。实验性光衰减被发现会增加腺芽孢杆菌和苔藓属植物中的氮浓度。在整个生长季节。在初夏，B.glutenulosa 中的酚类浓度下降，但在其他方面随着光衰减和积雪增加而保持一致。积雪的增加与环境光的结合对B. gearulosa的叶生物量产生了积极影响. 因此，灌木致密化造成的积雪和阴影增加可能会增加驯鹿的草料数量和质量。我们建议调查灌木扩张对驯鹿饮食其他成分的影响，例如地衣和杂草。