Lovelock Catherine E, Feller Ilka C, Adame Maria Fernanda, Reef Ruth, Penrose Helen M, Wei Lili, Ball Marilyn C
The School of Biological Science, The University of Queensland, Brisbane, Qld 4072, Australia.
Smithsonian Environmental Research Center, Smithsonian Institution, Edgewater, MD 21037, USA.
Funct Plant Biol. 2011 Jun;38(6):514-522. doi: 10.1071/FP11027.
Tropical cyclones can be devastating to ecosystems, but they can also result in pulses of fresh water and sediments delivered in floodwaters to the coastal zone. In the arid zone the pulses provided by cyclones may be particularly important for the maintenance of productivity. We examined the impacts of Cyclone Pancho on growth and nutrient limitations to growth in mangroves on the arid coast of Western Australia. We found that growth of trees was enhanced after the cyclone, more than doubling their rates of stem extension. Fertilisation studies showed that before the cyclone tree growth was nutrient limited. After the cyclone fertilisation treatments had no significant effect on growth, indicating nutrients had been delivered during the storm. Additionally, before the cyclone the efficiency of resorption of phosphorus and nitrogen from senescent leaves was higher than after the cyclone, suggesting that nutrient availability was enhanced. Analysis of stable isotopes of leaf tissue indicated that the cyclone was associated with small changes in water use efficiency, consistent with decreased soil salinity associated with the cyclone. There was, however, significant reductions in δ15N indicating enhanced N supply potentially from a new source. We conclude that in the arid zone, floodwater associated with cyclones is important for the delivery of nutrient subsidies that stimulate mangrove growth and that predicted future reductions in the frequency of cyclones will have negative impacts on the productivity of these ecosystems.
热带气旋对生态系统具有毁灭性，但它们也能带来淡水脉冲以及裹挟在洪水中的沉积物进入沿海地区。在干旱地区，气旋带来的脉冲对于维持生产力可能尤为重要。我们研究了潘乔气旋对西澳大利亚干旱海岸红树林生长以及生长的养分限制的影响。我们发现，气旋过后树木生长得到增强，其茎干延伸速率增加了一倍多。施肥研究表明，气旋来临前树木生长受养分限制。气旋过后，施肥处理对生长没有显著影响，这表明风暴期间养分已被输送进来。此外，气旋来临前衰老叶片中磷和氮的再吸收效率高于气旋过后，这表明养分有效性提高了。对叶片组织稳定同位素的分析表明，气旋与水分利用效率的微小变化有关，这与气旋导致的土壤盐分降低相一致。然而，δ15N显著降低，表明可能有新的氮源供应增加。我们得出结论，在干旱地区，与气旋相关的洪水对于提供刺激红树林生长的养分补贴很重要，并且预计未来气旋频率的降低将对这些生态系统的生产力产生负面影响。
