Differences in desiccation tolerance do not explain altitudinal distribution patterns of tropical bryophytes
Differences in desiccation tolerance do not explain altitudinal distribution patterns of tropical bryophytes
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DOI：
10.1179/1743282012y.0000000033
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发表时间：
2013-03
影响因子：
1.9
通讯作者：
M. Bader;T. Reich;S. Wagner;A. González González-A.-González-González-1700997426;G. Zotz
中科院分区：
文献类型：
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作者：
M. Bader;T. Reich;S. Wagner;A. González González-A.-González-González-1700997426;G. Zotz
摘要热带苔藓植物生物量和多样性随海拔高度变化很大。低地雨林中的低丰度和低物种数量最有可能是由于白天活动时间减少以及高温下夜间呼吸速率高。这可能使许多山地物种被排除在温暖的低地之外。然而，另一种假设解释了观察到的模式，即有限的干燥耐受性的山地物种，降水更集中，但不太频繁，在大多数低地森林相比，山地云雾林。为了验证这一假设，我们研究了四个山地和四个低地britrete物种的耐干燥性。长期干旱的影响进行了量化与叶绿素荧光（Fv/Fm）和电解质渗漏的程度。山地和低地物种都能在1080天的干旱期中存活下来，这远远超过了潮湿的低地热带地区的干旱期。因此，我们可以排除对长期干旱期的不耐受性作为低地没有被测试的山地物种的解释。我们应该继续关注其他机制来解释热带地区玄武岩丰度和多样性的海拔梯度，以了解这种模式，以及预测气候变暖下的未来趋势。
Abstract Bryophyte biomass and diversity vary strongly with altitude in the tropics. Low abundance and low species numbers in lowland rain forests are most likely due to reduced diurnal activity times combined with high nocturnal respiration rates at high temperatures. This may exclude many montane species from the warm lowlands. However, an alternative hypothesis explains the observed pattern, namely a limited desiccation tolerance of montane species, precipitation being more concentrated but less frequent in most lowland forests compared to montane cloud forests. To test this hypothesis, we studied the desiccation tolerance of four montane and four lowland bryophyte species. The effects of prolonged drought were quantified with chlorophyll fluorescence (Fv/Fm) and the extent of electrolyte leakage. Both montane and lowland species survived dry periods of ≧80 days, which far exceeds the duration of dry periods in the wet lowland tropics. We can thus exclude intolerance to long dry spells as an explaination for the absence of the tested montane species in the lowlands. We should continue to focus on other mechanisms to explain the altitudinal gradient of bryophyte abundance and diversity in the tropics, in order to understand this pattern, as well as to predict future trends under climatic warming.