Numer and type of seeds introduced by footwear of travelers to Svalbard and germination success in 2008

Expanding visitation to Polar regions combined with climate warming increases the potential for alien species introduction and establishment. We quantified vascular plant propagule pressure associated with different groups of travelers to the high-Arctic archipelago of Svalbard, and evaluated the potential of introduced seeds to germinate under the most favorable average Svalbard soil temperature (10°C). We sampled the footwear of 259 travelers arriving by air to Svalbard during the summer of 2008, recording 1,019 seeds: a mean of 3.9 (±0.8) seeds per traveler. Assuming the seed influx is representative for the whole year, we estimate a yearly seed load of around 270,000 by this vector alone. Seeds of 53 species were identified from 17 families, with Poaceae having both highest diversity and number of seeds. Eight of the families identified are among those most invasive worldwide, while the majority of the species identified were non-native to Svalbard. The number of seeds was highest on footwear that had been used in forested and alpine areas in the 3 months prior to traveling to Svalbard, and increased with the amount of soil affixed to footwear. In total, 26% of the collected seeds germinated under simulated Svalbard conditions. Our results demonstrate high propagule transport through aviation to highly visited cold-climate regions and isolated islands is occurring. Alien species establishment is expected to increase with climate change, particularly in high latitude regions, making the need for regional management considerations a priority.

极地地区旅游人次持续攀升叠加气候变暖，进一步提升了外来物种引入并成功定殖的风险。本研究量化了前往高北极斯瓦尔巴群岛的不同游客群体所携带的维管植物（vascular plant）繁殖体压力（propagule pressure），并在斯瓦尔巴群岛最适宜的平均土壤温度（10℃）条件下，评估了引入种子的萌发潜力。2008年夏季，我们对搭乘航空航班抵达斯瓦尔巴群岛的259名游客的鞋履进行了采样，共收集到1019粒种子，每名游客平均携带3.9±0.8粒种子。假设该夏季的种子输入量可代表全年水平，我们估算仅通过航空入境这一传播途径，每年输入的种子总量可达约27万粒。从17个植物科中共鉴定出53个物种的种子，其中禾本科（Poaceae）的物种多样性和种子数量均为最高。本次鉴定出的植物科中有8个属于全球入侵性最强的科之列，且绝大多数鉴定物种均为斯瓦尔巴群岛的非本土物种。在前往斯瓦尔巴群岛前3个月曾在森林与高山区域使用过的鞋履上，收集到的种子数量最多，且种子数量与鞋履上附着的土壤量呈正相关。总体而言，在所收集的种子中，有26%在模拟斯瓦尔巴群岛的环境条件下成功萌发。本研究结果证实，通过航空运输向旅游热度较高的寒带区域及偏远岛屿输入大量繁殖体的现象确实存在。随着气候变化，外来物种的定殖风险预计将进一步上升，高纬度地区尤甚，因此优先开展区域层面的管理防控工作已成为当务之急。