Leaf spectral reflectance is a crucial indicator of leaf physiology both in eco-physiology and remote sensing. To assess how alpine plants acclimate or adapt to altitudinal environments, we examined leaf optical properties at wavelengths from 280 to 1100 nm in 797 leaves of 38 broad-leaved herbaceous species along an altitudinal gradient from 3200 m to 4400 m on the northeastern Qinghai-Tibetan Plateau. The mean leaf reflectance of all observed species increased with altitude at a rate of 6.3 %, 3.1 %, and 2.3 % km^–1 in the ultraviolet (UV, 280–400 nm), photosynthetically active radiation (PAR, 400–700 nm), and near-infrared radiation (NIR, 700–1100 nm) regions, respectively. Increased leaf reflectance along the altitudes was found both within and among species. Within the UV region, a notable increase in spectral reflectance was observed at approximately 301 and 355 nm compared to other wavelengths. Within the PAR region, the peak wavelength of spectral reflectance shifted toward shorter wavelengths at a rate of 9.3 nm per km increase in altitude. The study suggests that alpine broad-leaved species can precisely adjust leaf reflectance. Therefore, it is essential to interpret plant physiology carefully by exploiting leaf spectral reflectance in diverse environments and plant species.

中文翻译：

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青藏高原阔叶植物叶片光谱反射率的海拔调节


叶片光谱反射率是生态生理学和遥感学中叶片生理学的重要指标。为了评估高山植物如何适应或适应海拔环境，我们研究了青藏高原东北部 3200 m 至 4400 m 海拔梯度上 38 种阔叶草本物种的 797 片叶片在 280 至 1100 nm 波长下的叶片光学特性。在紫外线（UV，280-400 nm）、光合有效辐射（PAR，400-700 nm）和近红外辐射（NIR，700-1100 nm）区域，所有观测物种的平均叶片反射率分别以 6.3 %、3.1 % 和 2.3 % ^km-1 的速率增加。在物种内部和物种之间都发现了沿海拔高度的叶片反射率增加。在紫外区域内，与其他波长相比，在大约 301 和 355 nm 处观察到光谱反射率显着增加。在 PAR 区域内，光谱反射率的峰值波长以高度每增加 9.3 nm 的速率向较短的波长移动。研究表明，高山阔叶物种可以精确调节叶片反射率。因此，必须通过利用不同环境和植物物种中的叶片光谱反射率来仔细解释植物生理学。