Littoral Slope, Water Depth and Alternative Response Strategies to Light Attenuation Shape the Distribution of Submerged Macrophytes in a Mesotrophic Lake
Littoral Slope, Water Depth and Alternative Response Strategies to Light Attenuation Shape the Distribution of Submerged Macrophytes in a Mesotrophic Lake
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滨海坡度、水深和对光衰减的替代响应策略塑造了中营养湖中沉水植物的分布
DOI：
10.3389/fpls.2019.00169
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发表时间：
2019-02-20
影响因子：
5.6
通讯作者：
Hilt, Sabine
中科院分区：
文献类型：
--
作者：
He, Liang;Zhu, Tanshun;Hilt, Sabine
光是水生生态系统的主要限制性资源，许多研究调查了沉水植物对弱光条件的反应。然而，很少有研究已经测试了不同的光响应策略是否也可以有后果的水生植物分布沿着不同的沿岸的斜坡湖泊，这是已知的影响水生植物生物量，由于阻力和沉积物特性的差异。在这项研究中，我们测试了（1）是否有两种不同的生长形式的大型植物（冠层形成：微刺眼子菜，莲座型：苦草）在其响应策略不同，以低光条件和（2）这些响应如何影响他们的分布沿着不同流域的斜坡，在中营养洱海，中国。我们假设，树冠形成的物种响应低光条件下，在较深的网站茎伸长，而莲座型的物种增加其叶绿素含量。因此，P. maackianus应该对拖曳力有更高的敏感性，因此在坡度较低的场地占优势。具有较高坡度的地点应该为玫瑰花型物种提供一个利基，如V. natans，可以更好地承受拖曳力。通过对洱海97条样带沿着527个采样点的调查，分析了洱海两种水生植物的分布和丰度，并测定了不同水深下两种水生植物的高度、叶和茎/根茎生物量以及叶绿素a含量。我们的研究结果证实了茎伸长作为一种策略，以低光条件下的冠层形成物种P. maackianus，而V. natans产生更多的叶绿素a每枝生物量在较深的网站，以容忍遮荫。正如假设的那样，这些替代的低光条件下的反应策略，导致在权衡植物的能力，生长在不同的盆地斜坡。在低-中度坡度（0-4%）和低-中度水深（2-4 m）的样地中，微囊藻占优势，而在高坡度（4-7%）和中-高水深（3-5 m）的样地中，浮游植物占优势。因此，后者的栖息地代表了一个潜在的避难所莲座型的水生植物物种，往往被淘汰时，遮光增加富营养化。
Light is a major limiting resource in aquatic ecosystems and numerous studies have investigated the response of submerged macrophytes to low light conditions. However, few studies have tested whether different light response strategies can also have consequences for macrophyte distribution along different littoral slopes in lakes, which are known to affect macrophyte biomass due to differences in drag forces and sediment characteristic. In this study, we tested (1) whether two macrophyte species of different growth forms (canopy-forming: Potamogeton maackianus, rosette-type: Vallisneria natans) differ in their response strategies to low light conditions and (2) how these responses influence their distribution along different basin slopes in the mesotrophic Lake Erhai, China. We hypothesized that the canopy-forming species responds to low light conditions at deeper sites by stem elongation while the rosette-type species increases its shoot chlorophyll content. As a consequence, P. maackianus should have a higher susceptibility to drag forces and thus prevail at sites with lower slopes. Sites with higher slopes should offer a niche for rosette-type species like V. natans that can better withstand drag forces. We surveyed the distribution and abundance of the two macrophyte species at 527 sampling points along 97 transects in Lake Erhai and measured their height, leaf and stem/rhizome biomass, and leaf chlorophyll a content at different water depths. Our results confirmed stem elongation as a strategy to low light conditions by the canopy-forming species P. maackianus, while V. natans produced more chlorophyll a per shoot biomass at deeper sites to tolerate shading. As hypothesized, these alternative response strategies to low light conditions resulted in a trade-off regarding the plants ability to grow at different basin slopes. P. maackianus was dominant at sites with low-moderate slope (0–4%) and low-moderate water depth (2–4 m), while sites with high basin slope (4–7%) combined with moderate-high water depth (3–5 m) were dominantly colonized by V. natans. The latter habitat thus represents a potential refuge for rosette-type macrophyte species that are often outcompeted when shading increases during eutrophication.