Changes in summer temperatures in Arctic Alaska have led to longer and warmer growing seasons over the last three decades. Corresponding with these changes in climate, the abundance and distributions of geese have increased and expanded over the same period. We used an experimental approach to assess the response of goose forage plants to simulated environmental change. We subjected Carex subspathacea, a preferred goose forage growing on the Arctic Coastal Plain (ACP) of Alaska, to manipulations of temperature and timing of spring thaw to measure potential effects in terms of plant nitrogen concentration, aboveground biomass, and total nitrogen availability. Carex subspathacea responded to warming in a dynamic fashion. Increases in temperature led to decreases in leaf nitrogen concentration but increases in aboveground biomass. The increase in biomass was stronger than the decline in nitrogen concentration such that total nitrogen availability was increased with temperature for the first 35–40 d of the season. Grazing removal accounted for only minimal offtake of biomass, and we found no indication that grazing maintained elevated levels of nitrogen concentration longer in the season as reported in other studies. Based on demonstrated relationships in the literature between forage nitrogen concentrations and gosling growth rates, we conclude that there is currently abundant high-quality forage available across the ACP. This finding fits with recent evidence of high gosling growth rates and increasing trends in goose abundance on the ACP. Our results suggest that with climate warming of a few degrees, nitrogen concentration of forage may decrease, but forage biomass and total nitrogen availability will increase. Our data suggest that nitrogen concentration will not fall below the minimum threshold required by geese in the near future. As such, we suggest that there is currently no bottom-up limitation to goose numbers on the ACP.

中文翻译：

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饲料植物对温度变化和春季解冻日期的反应：对北极变暖的鹅的影响

在过去的三十年里，阿拉斯加北极地区夏季气温的变化导致生长季节变得更长、更温暖。与这些气候变化相对应，鹅的数量和分布在同一时期有所增加和扩大。我们使用实验方法来评估鹅饲料植物对模拟环境变化的响应。我们对生长在阿拉斯加北极沿海平原 (ACP) 的首选鹅草 Carex subspathacea进行了温度和春季解冻时间的操纵，以测量植物氮浓度、地上生物量和总氮可用性方面的潜在影响。苔藓下苔藓以动态的方式应对变暖。温度升高导致叶氮浓度降低，但地上生物量增加。生物量的增加强于氮浓度的下降，因此在季节的前 35-40 天，总氮的可用性随着温度的升高而增加。放牧移除只占生物量的最小吸收，我们没有发现任何迹象表明放牧在本赛季中维持较高水平的氮浓度更长时间，如其他研究报告的那样。根据文献中证明的牧草氮浓度与小鹅生长率之间的关系，我们得出结论，目前整个 ACP 有丰富的高质量牧草可用。这一发现与最近关于 ACP 上鹅的高增长率和鹅丰度增加趋势的证据相吻合。我们的研究结果表明，随着气候变暖几度，牧草的氮浓度可能会下降，但牧草生物量和总氮可用性会增加。我们的数据表明，在不久的将来，氮浓度不会低于鹅所需的最低阈值。因此，我们建议目前对 ACP 上的鹅数量没有自下而上的限制。