School of Engineering, Institute of Energy Systems, University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh, EH9 3FB, United Kingdom.
Department of Biology and Botanic Garden, Ecology and Evolution, University of Fribourg, Chemin du Musée 10, Fribourg, CH-1700, Switzerland.
Am J Bot. 2020 Dec;107(12):1831-1838. doi: 10.1002/ajb2.1581. Epub 2020 Dec 20.
Seed dispersal is extremely important for the recovery and restoration of forest communities. Relict tree genus Zelkova possesses a unique dispersal mechanism: mature fruits fall with the entire twig, and the dried leaves that are still attached function as a drag-enhancing appendage, carrying the fruits away from the parent tree. This singular adaptation has never been investigated in Z. abelicea.
Drop tests with dispersal units and individual fruits of Z. abelicea were performed in controlled conditions to measure their dispersal velocity and to define their flight mode.
Zelkova abelicea uses both slowly falling dispersal units with chaotic motion, as well as fast falling individual fruits using a straight path. The falling velocity of Z. abelicea dispersal units is 1.53 m s , which is virtually identical to that of the East Asiatic Z. serrata (1.51 m s ). In contrast, the falling velocity of individual fruits was m s (Z. serrata: 5.36 m s ).
Members of the genus Zelkova, growing today in distant regions, show remarkable evolutionary conservation of the velocity and flight mechanics of their dispersal units. This is surprising because the Mediterranean and East Asiatic Zelkova species have been separated at least 15-20 mya. Zelkova abelicea, although growing in the Mediterranean with completely different forest structure and composition, still uses the same dispersal mechanism. The dispersal capacity of the genus Zelkova is less efficient than that of other wind dispersed trees, and it presumably evolved for short-distance ecological spread and not for long-distance biogeographical dispersal.
种子传播对于森林群落的恢复和重建至关重要。遗留下来的榉属树种具有独特的传播机制：成熟的果实与整根小枝一起掉落，而仍然附着的干燥叶片作为增强阻力的附属物，将果实从母树带走。这种独特的适应机制从未在 Z. abelicea 中被研究过。
在受控条件下对 Z. abelicea 的传播单元和单个果实进行了跌落测试，以测量它们的传播速度并定义它们的飞行模式。
Zelkova abelicea 既使用传播单元缓慢下落且运动混乱，也使用个体果实沿直线快速下落。Z. abelicea 传播单元的下落速度为 1.53 m s ，与东亚的 Z. serrata（1.51 m s ）几乎相同。相比之下，个体果实的下落速度为 m s （Z. serrata：5.36 m s ）。
今天在遥远地区生长的榉属植物，其传播单元的速度和飞行力学表现出惊人的进化保守性。这令人惊讶，因为地中海和东亚的榉属物种已经分离了至少 15-20 百万年。尽管在具有完全不同森林结构和组成的地中海生长，Z. abelicea 仍然使用相同的传播机制。榉属的传播能力不如其他风传播树木有效，它可能是为了短距离的生态传播而进化的，而不是为了长距离的生物地理传播。
