Testing trait plasticity over the range of spectral composition of sunlight in forb species differing in shade tolerance

• Published in: The Journal of ecology Vol. 108; no. 5; pp. 1923 - 1940
• Main Authors: Wang, Qing‐Wei, Robson, Thomas Matthew, Pieristè, Marta, Oguro, Michio, Oguchi, Riichi, Murai, Yoshinori, Kurokawa, Hiroko, Cao, Kun‐Fang
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.09.2020; Wiley
• Subjects: Attenuation; Biodiversity and Ecology; biomass production; blue light; Composition; Ecology, environment; Environmental Sciences; forbs; Forest ecosystems; forests; Functional groups; functional traits; green light; growth and development; Irradiance; Life Sciences; Light; light intensity; light niche; Light quality; phenotypical plasticity; Plant growth; red light; Shade; shade tolerance; Solar radiation; Species; Spectra; Spectral composition; Sunlight; temperate forests; Terrestrial ecosystems; transmittance; Ultraviolet radiation; understorey species; understory; spectral composition; light niche; temperate forests; phenotypical plasticity; functional traits; understorey species; solar radiation; shade tolerance
• ISSN: 0022-0477; 1365-2745
• DOI: 10.1111/1365-2745.13384

Although sunlight is essential for plant growth and development, the relative importance of each spectral region in shaping functional traits is poorly understood, particularly in dynamic light environments such as forest ecosystems. We examined responses of 25 functional traits from groups of 11 shade‐intolerant and 12 understorey shade‐tolerant forb species grown outdoors under five filter treatments differing in spectral transmittance: (a) transmitting c. 95% of solar radiation (280–800 nm); (b) attenuating ultraviolet‐B (UV‐B); (c) attenuating all UV; (d) attenuating all UV and blue light; (e) attenuating all UV, blue and green light. Our results show that UV‐B radiation mainly affected the biochemical traits but blue light mainly affected the physiological traits irrespective of functional strategy, whereas green light affected both sets of traits. This would suggest that differentiation among suites of functional trait responses proceeds according to light quality. Biomass accumulation was significantly increased by UV‐A radiation (contrasting treatment [b] vs. [c]) among shade‐intolerant but decreased by blue light among shade‐tolerant species; green and red light affected whole‐plant morphological development differently according to functional groups. Shade‐tolerant species were more plastic than shade‐intolerant species in response to each spectral region that we examined except for UV‐B radiation. Synthesis. Our results show that differences in the spectral composition of sunlight can drive functional trait expression irrespective of total irradiance received. The different responses of functional traits between functional groups imply that shade‐tolerant and intolerant species have adapted to utilize spectral cues differently in their respective light environments. 太阳光谱范围内森林植物功能性状的可塑性分异特征 摘要：太阳光对地球植物的重要性，不仅是因为它为地球植物生长和生产的光合过程提供所需能量，而且其光谱分区（从紫外到红光）作为信号来源特异性调节植物形态、生化和生理特征，从而直接或间接驱动陆地生态系统碳氮循环和生物多样性。尽管光生物学在分子遗传和农业园艺上受到了广泛关注，但在自然界，光谱生态学意义还没有得到足够的重视，比如在光环境变化剧烈的温带森林中，太阳光谱分区如何塑造植物功能性状，还不清楚。我们通过同质园控制实验，设置5种光谱处理：（1）透射太阳全光谱辐射（280‐800 nm）；（2）滤除紫外线B（UV‐B）（>315 nm）；（3）滤除所有紫外线（UV‐B /A）（>400 nm）；（4）滤除所有紫外线和蓝光（>500 nm）；（5）滤除所有紫外线，蓝光和绿光（>600 nm）条件下，分析了23种广布型草本植物（11个喜光种和12种林下耐阴种）5种功能类型（生化、生理、形态、结构与生长）的25种性状响应。结果表明：（1）UV‐B辐射主要驱动生化性状，蓝光主要塑造生理性状，而绿光对两种性状均有影响，这些影响与植物的耐阴或喜光习性无关，说明光谱分区是诱导功能性状响应分异的关键因素。（2）在喜光物种中，UV‐A辐射显著促进了生物量累积；但是在耐荫物种中，蓝光反而限制植物的生物量累积。（3）与喜光物种相比，耐荫物种对每个光谱分区（UV‐B除外）均具有较强的可塑性。结论：太阳光谱分区的差异能够显著驱动功能性状的表达，且与接收到的总辐照度无关；两种生态策略不同的功能组植物性状的响应差异，反映了不同植物对各自栖息地光谱信号特征的适应性；性状可塑性的多样性，可能会增加生态位分化或产生物种间竞争权衡，从而促进林下异质光环境中的物种共存。 Our results show that differences in the spectral composition of sunlight can drive functional trait expression irrespective of total irradiance received. The different responses of functional traits between functional groups imply that shade‐tolerant and intolerant species have adapted to utilize spectral cues differently in their respective light environments.