Annual species' experimental germination responses to light and temperature do not correspond with their microhabitat associations in the field

IF 2.2 3区环境科学与生态学 Q2 ECOLOGY Journal of Vegetation Science Pub Date : 2024-04-15 DOI:10.1111/jvs.13252

Isis A. da Silva, David J. Merritt, Todd E. Erickson, Margaret M. Mayfield, John M. Dwyer

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Abstract

Questions

Annual species have evolved sets of germination cues that are thought to be predictive of the post-germination environment. In naturally patchy environments, germination microsites often vary considerably in the amount of light they receive and in the diurnal temperature fluctuations they experience. However, whether species' differential germination responses to light and temperature are associated with their spatial patterns of occurrence remains largely untested.

Location

Mediterranean-climate woodlands in Southwest Western Australia.

Methods

We surveyed species' occurrences in annual plant communities in 150 quadrats across gradients of canopy cover and litter cover. Nineteen species recorded in this survey were then included in a germination experiment that manipulated (1) Light vs Dark (12 h light or continuous dark) approximating seeds near the soil surface vs those covered by litter and (2) Cold vs Warm temperature regimes (7/18°C and 7/24°C) approximating diurnal fluctuations experienced in shaded vs sun-exposed microsites, respectively.

Results

In the germination experiment, six species had highest germination probabilities in the Light treatment (regardless of temperature), five in Cold + Light, one in Warm + Light, two were indifferent to the treatments, and four did not germinate at all. Binomial linear mixed-effects models showed that species' maximum responses to light and temperature did not explain their spatial distributions along canopy cover and litter cover gradients, contrary to theoretical expectations of germination being a strong driver of species' occurrences.

Conclusions

Despite variation in species' responses to experimental treatments, no association was found with their field microsite associations. Germination strategies in our system were wider than expected for Mediterranean systems. Our results support that germination cues are not strong drivers of microhabitat associations in this system.

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一年生物种在实验中对光照和温度的发芽反应与其在野外的微生境关联不一致

问题一年生物种已经进化出一套萌芽线索，这些线索被认为可以预测萌芽后的环境。在自然斑块环境中，萌芽微生境所接受的光照量和昼夜温度波动往往有很大差异。然而，物种对光照和温度的不同发芽反应是否与其出现的空间模式有关，在很大程度上仍未得到验证。地点西澳大利亚州西南部的地中海气候林地。方法我们在150个四分格中调查了一年生植物群落中物种的出现情况，这些四分格跨越了树冠覆盖率和枯落物覆盖率的梯度。调查中记录的 19 个物种随后被纳入萌芽实验，该实验的操作方法为：（1）光照与黑暗（12 小时光照或连续黑暗），近似于土壤表面附近的种子与被枯落物覆盖的种子；（2）寒冷与温暖的温度制度（7/18°C 和 7/24°C），分别近似于阴暗微地与阳光照射微地的昼夜波动。结果在发芽实验中，6 个物种在光照处理中发芽概率最高（与温度无关），5 个物种在冷+光照处理中发芽，1 个物种在暖+光照处理中发芽，2 个物种对处理无动于衷，4 个物种完全没有发芽。二项式线性混合效应模型显示，物种对光照和温度的最大反应并不能解释它们在冠层覆盖和枯落物覆盖梯度上的空间分布，这与理论上认为发芽是物种出现的主要驱动力的预期相反。结论尽管物种对实验处理的反应存在差异，但并未发现它们与野外微地的关联。在我们的系统中，萌芽策略比预期的地中海系统更广泛。我们的研究结果表明，萌芽线索并不是该系统中微生境关联的主要驱动因素。

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来源期刊

Journal of Vegetation Science 环境科学-林学

CiteScore

6.00

自引率

3.60%

发文量

审稿时长

2 months

期刊介绍： The Journal of Vegetation Science publishes papers on all aspects of plant community ecology, with particular emphasis on papers that develop new concepts or methods, test theory, identify general patterns, or that are otherwise likely to interest a broad international readership. Papers may focus on any aspect of vegetation science, e.g. community structure (including community assembly and plant functional types), biodiversity (including species richness and composition), spatial patterns (including plant geography and landscape ecology), temporal changes (including demography, community dynamics and palaeoecology) and processes (including ecophysiology), provided the focus is on increasing our understanding of plant communities. The Journal publishes papers on the ecology of a single species only if it plays a key role in structuring plant communities. Papers that apply ecological concepts, theories and methods to the vegetation management, conservation and restoration, and papers on vegetation survey should be directed to our associate journal, Applied Vegetation Science journal.