Leininger Theodor D, Gardiner Emile S, Lockhart Brian Roy, Schiff Nathan M, Wilson Alphus Dan, Devall Margaret S, Hamel Paul B, Connor Kristina F
USDA Forest Service Southern Research Station Center for Bottomland Hardwoods Research Stoneville MS USA.
Formerly with USDA Forest Service Southern Research Station Center for Bottomland Hardwoods Research Stoneville MS USA.
Ecol Evol. 2021 Aug 22;11(19):13153-13165. doi: 10.1002/ece3.8037. eCollection 2021 Oct.
We studied the impact of flooding and light availability gradients on sexual and asexual reproduction in (Walt.) Blume, an endangered shrub found in floodplain forests of the Mississippi Alluvial Valley (MAV), USA. A water impoundment facility was used to control the duration of soil flooding (0, 45, or 90 days), and shade houses were used to control light availability (high = 72%, intermediate = 33%, or low = 2% of ambient light) received by established on native soil of the MAV. Sexual reproductive intensity, as measured by inflorescence bud count, fruit set, and drupe production, was greatest in the absence of soil flooding. Ninety days of soil flooding in the year prior to anthesis decreased inflorescence bud counts, and 45 days of soil flooding in the year of anthesis lessened fruit set and drupe production. Inflorescence bud development was the greatest in environments of intermediate light, decreased in high-light environments, and was absent in low light environments. But low fruit set diminished drupe production in intermediate light environments as compared to high light environments. Asexual reproduction, as measured by development of new ramets, was greatest in the absence of soil flooding and where plants were grown in high or intermediate light. Plants exhibited plasticity in reproductive mode such that soil flooding increased the relative importance of asexual reproduction. The high light environment was most favorable to sexual reproduction, and reproductive mode transitioned to exclusively asexual in the low light environment. Our results raise several implications important to active management for the conservation of this imperiled plant.
我们研究了洪水和光照可利用度梯度对美国密西西比河冲积河谷（MAV）河漫滩森林中一种濒危灌木——（沃尔特）布卢姆的有性和无性繁殖的影响。利用一个蓄水设施来控制土壤水淹持续时间（0、45或90天），并使用遮荫棚来控制在MAV原生土壤上种植的植株所接受的光照可利用度（高光=环境光的72%，中度=33%，或低光=2%）。通过花序芽数、坐果率和核果产量衡量的有性繁殖强度在没有土壤水淹的情况下最大。花期前一年90天的土壤水淹减少了花序芽数，花期当年45天的土壤水淹降低了坐果率和核果产量。花序芽发育在中度光照环境中最大，在高光环境中减少，在低光环境中则不存在。但与高光环境相比，中度光照环境中较低的坐果率降低了核果产量。通过新分株发育衡量的无性繁殖在没有土壤水淹以及植株生长在高光或中度光照条件下时最大。植株在繁殖方式上表现出可塑性，即土壤水淹增加了无性繁殖的相对重要性。高光环境最有利于有性繁殖，而在低光环境中繁殖方式转变为完全无性繁殖。我们的研究结果对这种濒危植物的保护积极管理具有若干重要意义。
