Marteau Audrey, Fourmaux Martin, Mevy Jean-Philippe
IMBE-UMR CNRS 7263/IRD 237, Aix Marseille University, Avignon University, 13331 Marseille, France.
Plants (Basel). 2023 Feb 15;12(4):879. doi: 10.3390/plants12040879.
The goal of this study was to observe the neighbor effect of Gorse, a plant of the Fabaceae family, on three typical species of Mediterranean shrubland: kermes oak, white Cistus and rosemary. For this purpose, a hyperspectral analysis and the application of vegetation indices (VIs) were carried out. We provide the spectral signature of Gorse, which differs mainly from that of its companion species in the band between 700 and 1350 nm. This supposed Gorse effect was tested in natural conditions and in conditions of forced drought to simulate the effects of the climate change predicted for the Mediterranean Basin. Field spectrometry demonstrated the existence of such interactions between the four species. In control stands, the presence of Gorse significantly modifies the spectral responses of kermes, white Cistus and rosemary, mainly in the near-infrared region (700-1350 nm). Both tri- and tetra-specific plant assemblages also exhibited spectral changes, suggesting an indirect effect of Gorse. Under drought conditions, one-way ANOVA followed by Fisher's LSD test led us to identify the features involved in plants' coexistence with Gorse. The reflectance spectrum was clearly increased in the presence of Gorse in rain-exclusion conditions. The application of several VIs allowed us to extract new information on the variation of spectral signatures. Unexpectedly, nitrogen supply by Gorse was not shown, except for Cistus, as shown by the VI NDVI (N) analysis. However, this study proved that Gorse can modify the behavior of its companion species in controls, but also in drought conditions, by increasing their photosynthesis activity (NIRvP) and water content (ratio R975/R900). Gorse therefore appears as a key species in the ecosystem of the Mediterranean shrubland, but its high vulnerability to drought leaves a vacant ecological niche in plant communities. While the spectral reflectance increases linearly with the specific richness in the lack of any disturbance, by contrast, climate aridification imposes a double reciprocal profile. This clearly means that multispecific plant communities cope better with climate change. Nevertheless, knowledge of the underlying mechanisms requires further structural, chemical, and biochemical investigation.
胭脂虫栎、白色岩蔷薇和迷迭香。为此，进行了高光谱分析并应用了植被指数（VIs）。我们提供了金雀花的光谱特征，其主要在700至1350纳米波段与其伴生种不同。这种假定的金雀花效应在自然条件和强制干旱条件下进行了测试，以模拟地中海盆地预测的气候变化影响。野外光谱分析证明了这四个物种之间存在这种相互作用。在对照林分中，金雀花的存在显著改变了胭脂虫栎、白色岩蔷薇和迷迭香的光谱响应，主要在近红外区域（700 - 1350纳米）。三物种和四物种植物组合也表现出光谱变化，表明金雀花有间接影响。在干旱条件下，通过单向方差分析和费舍尔最小显著差异检验，我们确定了植物与金雀花共存所涉及的特征。在防雨条件下，有金雀花时反射光谱明显增加。应用几种植被指数使我们能够提取关于光谱特征变化的新信息。如植被指数归一化植被指数（N）分析所示，除了岩蔷薇外，未显示金雀花提供氮素。然而，本研究证明，金雀花可以通过提高其伴生种的光合作用活性（近红外光与光合作用有效辐射比值）和含水量（975纳米与900纳米反射率比值），在对照条件下以及干旱条件下改变其伴生种的行为。因此，金雀花似乎是地中海灌木丛生态系统中的关键物种，但其对干旱的高脆弱性在植物群落中留下了一个空缺的生态位。在没有任何干扰的情况下，光谱反射率随物种丰富度线性增加，相比之下，气候干旱化呈现出双倒数曲线。这清楚地表明多物种植物群落能更好地应对气候变化。然而，对潜在机制的了解需要进一步的结构、化学和生化研究。
