Algal community response to experimental and interannual variation in hydrology in an Alaskan boreal fen
Algal community response to experimental and interannual variation in hydrology in an Alaskan boreal fen
复制标题
阿拉斯加北方沼泽中藻类群落对水文实验和年际变化的响应
DOI：
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发表时间：
2012
影响因子：
1.8
通讯作者：
R. Stevenson
中科院分区：
文献类型：
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作者：
A. Rober;Kevin H. Wyatt;M. Turetsky;R. Stevenson
摘要。植物区系研究表明，北方北方泥炭地中微藻丰富，但我们对其生态学知之甚少，也不知道它们将如何应对气候变化带来的环境条件变化。我们研究了在阿拉斯加沼泽地暴露于长期地下水位操纵的地点的藻类群落结构的变化，包括干旱（降低地下水位处理），洪水（提高地下水位处理）和对照（无操纵）处理。在前几年，持续的藻类定植通常只发生在提高地下水位的处理中，但春季洪水淹没了实验地块，提供了一个独特的机会来检查藻类群落对长期干旱后再湿润的反应。这一事件使我们能够研究在长期干旱后，与连续被洪水淹没的地点相比，对先前的地下水位操纵的生态系统记忆在多大程度上调节了分类群重新定居的能力。尽管采样时不同处理的地下水位位置没有差异，但春季解冻后地下水位降低处理的地表水营养物质浓度高于其他处理。这种差异与较低地下水位处理的藻类丰度和生物体积相对于对照和较高地下水位处理相对应。丰度和生物量的增加主要是由丝状绿藻（绿藻）驱动的，特别是水藻、水绵藻和小孢子藻。在地下水位升高处理中硅藻含量最多，而在对照处理中绿藻含量最多。在所有地下水位处理中，随着时间的推移，营养物和地下水位下降，固氮蓝藻数量增加。不同地下水位处理下藻类群落结构的差异表明，气候变化导致的旱涝交替事件可能会显著改变北方湿地藻类驱动的功能。
Abstract. Floristic studies indicate the abundance of microalgae in northern boreal peatlands, but we know relatively little about their ecology or how they will respond to changes in environmental conditions expected in this region as climate changes. We examined changes in algal community structure at sites exposed to a long-term water-table manipulation, including drought (lowered water-table treatment), flooding (raised water-table treatment), and control (no manipulation) treatments in an Alaskan fen. In previous years, continuous algal colonization typically would have occurred only in the raised water-table treatment, but a spring flood inundated experimental plots and provided a unique opportunity to examine algal community response to rewetting after long-term drought. This event allowed us to investigate how much ecosystem memory of the antecedent water-table manipulations regulated the ability of taxa to recolonize sites after prolonged drought compared to sites that had been continuously flooded. Despite no differences in water-table position among treatments at the time of sampling, surface-water nutrient concentrations were higher in the lowered water-table treatment relative to the other treatments after the spring thaw. This difference corresponded with greater algal abundance and biovolume in the lowered water-table treatment relative to the control and raised water-table treatments. Higher abundance and biovolume was driven mainly by filamentous green algae (Chlorophyta), especially Oedogonium, Spirogyra, and Microspora. Diatoms were most abundant in the raised water-table treatment, whereas chrysophytes were most abundant in the control treatment. Across all water-table treatments, N-fixing cyanobacteria increased as nutrients and water-table position declined over time. The differences in algal community structure among water-table treatments suggest that alternating drought and flooding events expected with climate change may significantly alter algal-driven functions in boreal wetlands.