Leaf density and chemical composition explain variation in leaf mass area with spectral composition among 11 widespread forbs in a common garden

Abstract

Leaf mass per area (LMA) is a key leaf functional trait correlated with plant strategies dictating morphology, physiology, and biochemistry. Although sunlight is generally accepted as a dominant factor driving LMA, the contribution of each spectral region of sunlight in shaping LMA is poorly understood. In the present study, we grew 11 widespread forb species in a common garden and dissected the traits underpinning differences in LMA, such as its morphological components (leaf density [LD] and leaf thickness [LT]), macroelement, and metabolite composition under five spectralattenuation treatments: (1) transmitting c. 95% of the whole solar spectrum (> 280 nm), (2) attenuating ultraviolet-B radiation (UV-B), (3) attenuating both UV-A and UV-B radiation, (4) attenuating UV radiation and blue light, (5) attenuating UV radiation, blue, and green light. We found that LMA, LD, and chemical traits varied significantly across species depending on spectral treatments. LMA was significantly increased by UV-B radiation and green light, while LD was increased by UV-A but decreased by blue light. LMA positively correlated with LD across treatments but was only weakly related to LT, suggesting that LD was a better determinate of LMA for this specific treatment. Regarding leaf elemental and metabolite composition, carbon, nitrogen, and total phenolics were all positively correlated with LMA, whereas lignin, non-structural carbohydrates, and soluble sugars had negative relationships with LMA. These trends imply a tradeoff between biomass allocation to structural and metabolically functional components. In conclusion, sunlight can spectrally drive LMA mainly through modifying functional and structural support.

Links between leaf anatomy and leaf mass per area of herbaceous species across slope aspects in an eastern Tibetan subalpine meadow

“…One possibility is that high ETs include thick cuticles, whose density is much higher than that of epidermis and mesophyll tissues (Onoda et al, 2012 ; Schreiber & Schönherr, 1990 ). The lignification of epidermal cells, small cell size, and/or higher proportions of vascular tissues and sclerenchyma may also be involved in high LD (Van Arendonk & Poorter, 1994 ; Castro‐Díez et al, 2000 ; Wang et al, 2021 ).…”

Interactive effects of changes in UV radiation and climate on terrestrial ecosystems, biogeochemical cycles, and feedbacks to the climate system

“…As well as species distribution, climatological data that include regional UV-B irradiances can be applied to study whether climatic trends correlate with patterns in plant functional traits among species. For example, a large-scale study of 1192 grassland species found that UV radiation was negatively correlated with leaf size across the Mongolian and Tibetan Plateau [ 274 ], while leaf shape, reflectance, and thickness have also been found to covary with UV-B radiation along environmental gradients [ 275 – 277 ].…”

A trade-off between leaf hydraulic efficiency and safety across three xerophytic species in response to increased rock fragment content

“… 2021 b ). Therefore, modifications of the leaf vein system associated with leaf embolism resistance might translate into leaf tissue density, which could have a direct effect on LMA ( Wang et al. 2021 ).…”