Data from: Seed dispersers help plants to escape global warming

Plants are shifting their ranges towards higher elevations in response to global warming, yet such shifts are occurring at a rate slower than is needed to keep pace with a rapidly changing climate. There is, however, an almost complete lack of knowledge on seed dispersal across altitude, a key process to understand what constrains climate-driven range shifts. Here, we report the first direct empirical evidence on altitudinal seed dispersal mediated by two common frugivorous mammals: the red fox Vulpes vulpes and the pine marten Martes martes. We conducted a three-year (bait-marking) experiment in a mountainous region of Spain. We offered experimental fruits containing colour-coded seed mimics at feeding stations that simulated source trees. The colour codes allowed us to identify the exact origin of seed mimics found later in mammal scats. Nearly half (47%) of the dispersal events occurred towards higher elevations, despite only ca 25% of the study area being above the average altitude of the feeding stations (1344 m). Seeds dispersed uphill gained an average of 106 m (median = 111 m) and a maximum of 288 m, greatly exceeding the estimated requirements to escape warming (35.4 m per decade). Yet, foxes mediated much more uphill seed dispersal than martens (57% and 26% of dispersal events, respectively), which can be explained by between-disperser differences in home range size and habitat specificity. Dispersers with larger home ranges move farther and potentially disperse more seeds to higher altitudes, while habitat generalism is necessary to transport seeds above vegetation belts delimiting contrasting habitat types. We discuss how both traits (home range size and habitat specificity) can be used to infer altitudinal seed dispersal across disperser species and mountainous landscapes.受全球变暖影响，植物正朝着更高海拔区域迁移其分布范围，但此类迁移的速率滞后于快速变化的气候所需的节奏。然而目前学界几乎完全缺乏对跨海拔种子扩散的认知——这是理解气候驱动的分布范围迁移受何种因素制约的关键过程。本研究首次提供了由两种常见食果哺乳动物介导的跨海拔种子扩散的直接实证证据：赤狐（Vulpes vulpes）与松貂（Martes martes）。我们在西班牙某山区开展了为期三年的诱饵标记实验，在模拟果实母树的投食点放置了搭载颜色编码种子模拟物的实验果实。通过颜色编码体系，我们能够精准识别后续在哺乳动物粪样中发现的种子模拟物的确切来源。尽管研究区域中仅有约25%的区域高于投食点的平均海拔（1344米），但近半数（47%）的扩散事件均朝向更高海拔区域发生。向高处扩散的种子平均海拔提升了106米（中位数为111米），最高可达288米，这远高于物种躲避气候变暖所需的估计迁移速率（每十年35.4米）。然而赤狐介导的向高处种子扩散比例远高于松貂（分别占扩散事件的57%与26%），这一差异可通过两种扩散者在家域大小与生境特异性上的不同加以解释。家域更大的扩散者移动距离更远，更有可能将种子扩散至更高海拔区域；而要将种子输送至划分不同生境类型的植被带以上，则需要具备广适性的生境偏好。我们进一步讨论了如何利用家域大小与生境特异性这两个特征，推断不同扩散者物种以及山地景观中的跨海拔种子扩散情况。