Gardiner Emile S, Leininger Theodor D, Connor Kristina F, Devall Margaret S, Hamel Paul B, Schiff Nathan M, Wilson A Dan
Center for Bottomland Hardwoods Research, Southern Research Station, USDA Forest Service, 432 Stoneville Road, Stoneville, MS 38776, USA.
Formerly with the Center for Bottomland Hardwoods Research, Southern Research Station, USDA Forest Service, 432 Stoneville Road, Stoneville, MS 38776, USA.
Conserv Physiol. 2023 Jul 19;11(1):coad051. doi: 10.1093/conphys/coad051. eCollection 2023.
is an endangered shrub indigenous to the broadleaf forest of the Mississippi Alluvial Valley (MAV). In this region, extant colonies of the species are found in periodically ponded habitats where a diversity of broadleaf trees can form well-developed overstory and sub-canopies-these habitat characteristics suggest that soil flooding and light availability are primary drivers of ecophysiology. To understand how these two factors affect its photosynthetic capacity, we quantified leaf characteristics and photosynthetic response of plants grown in a large-scaled, field setting of three distinct soil flooding levels (no flood, 0 day; short-term flood, 45 days; and extended flood, 90 days) each containing three distinct light availability levels (high light, 30% shade cloth; intermediate light, 63% shade cloth; and low light, 95% shade cloth). leaves showed marked plasticity to interacting effects of flooding and light with lamina mass per unit area (L) varying 78% and total nitrogen content per unit area (N) varying 63% from the maximum. Photosynthetic capacity (A) ranged 123% increasing linearly with N from low to high light. Extended flooding decreased the slope of this relationship 99% through a reduction in N availability and metabolic depression of A relative to N. However, neither soil flooding nor light imposed an additive limitation on photosynthetic capacity when the other factor was at its most stressful level, and the A-N relationship for plants that experienced short-term flooding suggested post-flood acclimation in photosynthetic capacity was approaching the maximal level under respective light environments. Our findings provide evidence for wide plasticity and acclimation potential of . photosynthetic capacity, which supports active habitat management, such as manipulation of stand structure for improved understory light environments, to benefit long-term conservation of the species in the MAV.
是一种濒危灌木，原产于密西西比河冲积平原（MAV）的阔叶林。在该地区，该物种现存的群落分布在周期性积水的栖息地，那里多种阔叶树可形成发育良好的上层林冠和亚林冠——这些栖息地特征表明土壤淹水和光照可用性是生态生理学的主要驱动因素。为了解这两个因素如何影响其光合能力，我们在大规模田间设置中，对生长在三种不同土壤淹水水平（无淹水，0天；短期淹水，45天；长期淹水，90天）下的植物的叶片特征和光合响应进行了量化，每种淹水水平又包含三种不同的光照可用性水平（高光，30%遮阳网；中度光照，63%遮阳网；低光照，95%遮阳网）。叶片对淹水和光照的相互作用表现出显著的可塑性，单位面积叶片质量（L）变化78%，单位面积总氮含量（N）相对于最大值变化63%。光合能力（A）在低光到高光条件下随N线性增加，增幅达123%。长期淹水通过降低N可用性和相对于N的A代谢抑制，使这种关系的斜率降低了99%。然而，当另一个因素处于最胁迫水平时，土壤淹水和光照都不会对光合能力施加累加限制，并且经历短期淹水的植物的A-N关系表明，淹水后光合能力的适应性在各自的光照环境下接近最大水平。我们的研究结果为该物种光合能力的广泛可塑性和适应潜力提供了证据，这支持了积极的栖息地管理，例如通过操纵林分结构来改善林下光照环境，以利于MAV地区该物种的长期保护。
