Competition for light as a bottleneck for endangered fen species: An introduction experiment
Competition for light as a bottleneck for endangered fen species: An introduction experiment
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DOI：
10.1016/j.biocon.2018.02.002
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发表时间：
2018-04-01
影响因子：
5.9
通讯作者：
van Diggelen, Rudy
中科院分区：
文献类型：
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作者：
Emsens, Willem-Jan;Aggenbach, Camiel J. S.;van Diggelen, Rudy
许多濒危植物物种仍然缺席重新润湿，以前排水fens.We进行了为期3年的引进实验，濒危沼泽物种（9苔草和6 bradyte物种）在4个水文恢复沼泽，调查哪些因素阻碍建立和生存。苔草属植物以成株和幼苗形式引种，藓类植物以配子体形式引种。介绍（最初）裸露的土壤，这使我们能够排除过度竞争的光在第一年。第一年的移植存活率高，在所有的沼泽（平均存活率= 96%），表明没有直接的非生物限制建立。然而，生存分析表明，在土壤表面的相对光照强度（RLI）在连续几年下降（表明增加了生物竞争的光）驱动高死亡率在大多数物种。因此，总的最终生存率最低的两个生产力最高（低光）fens（平均生存= 38%），而大多数移植坚持在两个生产力较低（高光）fens（平均生存= 79%）。高和快速增长的苔草物种能够超越土壤表面附近的光限制，因此有一个更高的整体生存能力比较小和生长缓慢的物种。光限制也导致了6种中5种的损失。我们认为，扩散限制和对光的不对称竞争可以解释小型和濒危植物物种在再湿润沼泽中的缺乏和损失。最小经验阈值为C。成功引种需要土壤表面附近30%的相对光照强度。
Many endangered plant species remain absent in rewetted, previously drained fens.We performed a 3-year introduction experiment with endangered fen species (9 Carex- and 6 bryophyte species) in 4 hydrologically restored fens to investigate which factors hamper establishment and survival. Carex species were introduced as adults and seedlings, mosses as gametophytes. Introductions were done on (initially) bare soil, which allowed us to exclude excessive competition for light during the first year.First year survival of the transplants was high in all fens (mean survival = 96%), indicating that there were no direct abiotic constraints on establishment. However, survival analysis revealed that a decrease in relative light intensity (RLI) at the soil surface during consecutive years (indicating an increase in biotic competition for light) drove high mortality rates in most species. As a result, overall final survival was lowest in the two most productive (low light) fens (mean survival = 38%), while most transplants persisted in the two less productive (high light) fens (mean survival = 79%). Taller and faster-growing Carex species were able to outgrow light limitation near the soil surface, and thus had a higher overall survivability than smaller and slower-growing species. Light limitation also drove the loss of 5 out of 6 bryophyte species.We conclude that both dispersal limitation and asymmetric competition for light may explain the lack and loss of small and endangered plant species in rewetted fens. A minimum empirical threshold of c. 30% relative light intensity near the soil surface is required for successful introduction.