Shoot growth and nitrogen responses to simulated herbivory in Kenyan seagrasses
Shoot growth and nitrogen responses to simulated herbivory in Kenyan seagrasses
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DOI：
10.1515/bot.2005.010
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发表时间：
2005-01-01
期刊：
影响因子：
2.2
通讯作者：
Mariani, S
中科院分区：
文献类型：
--
作者：
Alcoverro, T;Mariani, S
研究了食草动物落叶对6种热带海草（Thalassia hemprichii、Thalassodendron ciliatum、Cymopera rotundata、Cymopera serrulata、Halocomyanuninervis和Syringodium isoetifolium）叶片伸长和叶片营养动态的影响。落叶（修剪）处理导致在三个研究的六个海草叶伸长减少。修剪植物地块的平均芽再生长分别为45%，51%，和53%，低于在控制Thalassodendronciliatum，丁香，和Cyrnopolia serrulata。修剪对完全展开的嫩叶的氮含量影响不大，除了一个物种，Thalassodendron ciliatum（氮减少20%）。然而，有显着减少的氮在衰老的叶片中的处理植物比对照植物的叶片中的Thalassodendron ciliatum，盐藻，Cymopla serrulata和Cymopla rotundata。氮再吸收效率从叶子平均高出35%，在落叶植物比对照组中的6个物种，支持的假设，在海草再吸收可能是塑料的内部营养库的大小的变化。在这项研究中，海草似乎受到草食动物压力的影响。除了一个物种（Thalassia hemprichii），在那里的增长和氮库没有响应的治疗，修剪增加了海草的氮吸收效率，部分补偿的增长减少，落叶后发生。落叶响应叶伸长率下降的幅度与物种的再吸收能力，表明氮可以减少在衰老叶片的水平可能不是恒定的所有海草物种，这种可塑性将决定成功的再吸收作为氮保护机制时，氮损失发生的后果草食动物。
We investigated the effects of defoliation by herbivores on leaf elongation and foliar nutrient dynamics in six tropical seagrasses (Thalassia hemprichii, Thalassodendron ciliatum, Cymodocea rotundata, Cymodocea serrulata, Halodule uninervis and Syringodiurn isoetifolium). Defoliation (clipping) treatment resulted in decreased leaf elongation in three of the six seagrasses studied. Mean shoot re-growth of clipped plant plots was 45%, 51 %, and 53% lower than in controls in Thalassodendron ciliatum, Syringodiurn isoetifolium, and Cyrnodocea serrulata, respectively. Clipping had little effect on the nitrogen content of young, fully expanded leaves, except in one species, Thalassodendron ciliatum (20% reduction in nitrogen). However, there was significantly less nitrogen in senesced leaves of treated plants than in the leaves of control plants of Thalassodendron ciliatum, Halodule uninervis, Cymodocea serrulata and Cymodocea rotundata. Nitrogen resorption efficiencies from leaves averaged 35% higher in defoliated plants than in controls in five of the six species, supporting the hypothesis that resorption in seagrasses may be plastic in response to changes in the magnitude of internal nutrient pools. Seagrasses in this study seem to be variably affected by herbivore pressure. Except for one species (Thalassia hemprichii), where growth and nitrogen pools did not respond to the treatment, clipping increased the nitrogen resorption efficiency of seagrasses, partially compensating for the reduction in growth that occurred following defoliation. The magnitude of the fall in leaf elongation rate in response to defoliation was correlated with the species' resorption proficiency, indicating that the levels to which nitrogen can be reduced in senescing leaves is probably not constant in all seagrass species, and this plasticity will determine the success of resorption as a nitrogen conservation mechanism when nitrogen losses occur as a consequence of herbivory.