Size-dependent flowering and costs of reproduction affect population dynamics in a tuberous perennial woodland orchid
Size-dependent flowering and costs of reproduction affect population dynamics in a tuberous perennial woodland orchid
复制标题
DOI：
10.1111/j.1365-2745.2010.01697.x
复制
发表时间：
2010-09-01
影响因子：
5.5
通讯作者：
Jongejans, Eelke
中科院分区：
文献类型：
--
作者：
Jacquemyn, Hans;Brys, Rein;Jongejans, Eelke
P>1。在林地草本植物中，开花的概率和与繁殖相关的成本可能在很大程度上取决于环境背景（阴影与光照栖息地）和植物大小。这对于栖息在林地的块茎兰来说可能尤其如此，因为入射辐射量和总叶面积强烈地决定了光合能力，从而决定了可以转移到地下储存器官的碳水化合物的量，这些储存器官形成明年的莲座和花梗。为了充分理解在不同光照条件下依赖于大小的繁殖对种群动态的影响，生命周期模型应该以连续的方式包括植物大小。在这项研究中，每年的变化，植物大小和人口统计学行为的块茎多年生兰花红门兰purpurea连续7年（2003-2009年）在开放和遮荫林地进行了监测。利用积分投影模型（IPM）和生命表响应实验（LTRE）研究了植物大小的变化对该物种总体种群动态的影响程度，并将疏林和荫林种群之间的种群增长率差异分解为生长、存活和繁殖的贡献.在阴影和光照环境中的植物都需要一定的大小才能开始开花，但这个阈值大小在阴影环境中几乎是在光照环境中的三倍。在开放的林地中的植物开花更频繁，开花后的大小退化更少，并且比在阴影环境中的植物产生更多的果实，从而导致更大的种群增长率。我们的生命周期模型显示，繁殖的成本，在人口水平上衡量，在光环境中是小的，比非开花植物相比，开花植物的生存增加缓冲。然而，在阴凉环境中，繁殖成本是显着的，并在稳定（当前）和增长（没有繁殖成本）的人口之间产生差异。合成.土壤透光率是决定林地兰花种群动态的关键变量。我们的分析表明，与大小相关的繁殖（开花）和生长的生命率的差异是在不同的光环境中兰花种群动态变化的重要驱动因素。IPM和LTREs的组合，因此被证明是非常有用的，当研究的健身后果的大小和上下文相关的现象，如开花策略和繁殖成本。
P>1. In woodland herbs, the probability of flowering and costs associated with reproduction may strongly depend on environmental context (shade vs. light habitats) and on plant size. This may be particularly true for tuberous orchids that inhabit woodlands, as the amount of incoming radiation and total leaf area strongly determine photosynthetic capacity and hence the amount of carbohydrates that can be relocated to below-ground storage organs that form next year's rosette and flowering stalk.2. To fully comprehend the impact of size-dependent reproduction on population dynamics under varying light conditions, life cycle models should therefore include plant size in a continuous manner. In this study, annual changes in plant size and demographic behaviour of the tuberous perennial orchid Orchis purpurea were monitored during seven consecutive years (2003-2009) in open and shaded woodland. Integral projection models (IPMs) and life table response experiments (LTRE) were used to investigate the extent to which variation in plant size affected the overall population dynamics of this species and to decompose differences in population growth rates between populations of open and shaded woodland into contributions from growth, survival and reproduction.3. Both plants in shaded and light environments needed to be a certain size to initiate flowering, but this threshold size was almost three times as large in shaded environments as in light environments. Plants in open woodlands flowered more frequently over the years, showed less size regression after flowering and produced significantly more fruits than plants in shaded environments, resulting in significantly larger population growth rates.4. Our life cycle models revealed that costs of reproduction, measured at the population-level, were small in the light environment, and more than buffered by the increase in survival of flowering plants compared to non-flowering plants. In the shade environment, however, the costs of reproduction were significant and made the difference between a stable (current) and a growing (without reproduction costs) population.5. Synthesis. Light penetration to the soil is a key variable determining population dynamics of woodland orchids. Our analyses show that differences in vital rates related to size-dependent reproduction (flowering) and growth are essential drivers of changes in orchid population dynamics in different light environments. The combination of IPMs and LTREs thus proves to be very useful when studying the fitness consequences of size- and context-dependent phenomena like flowering strategies and costs of reproduction.