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Introduction
Plant community composition is a function, in part, of changing habitats along environmental gradients (Bello et al. 2013). Environmental disturbance caused by human activities have significant impacts on the diversity of native plant communities, with generally negative effects depending on mode and intensity of perturbation (Coffin 2007). These disturbances, such as coal mining (Pandey et al. 2014), road construction (Zardare et al. 2018), agricultural practices (Proulx and Mazumder 1998; Cousins 2006), and industrial outputs (Sayara et al. 2016), have all been shown to have a negative impact on the diversity of native plant communities due to altered habitats with foreign species invasion, interfered nutrients conduits, imported pollutants, and declined light conditions, among others. Although studies have very often demonstrated biodiversity loss due to increasing human activities, other studies show positive correlations between plant diversity and human activities. For instance, anthropogenic path formation (Root‐Bernstein and Svenning 2018) and total disturbance (Sahu et al. 2008) sometimes have a positive effect on the native plant diversity, the positive effects were possibly due to long‐distance linkages of propagules and nutrients, nutrient cycling, and so on. A leading theory about how environmental disturbances affect species diversity is the “intermediate disturbance hypothesis” (Connell 1978), however, recent ideas and models challenged this hypothesis and raised reasons that are not commonly recognized (Fox 2013). Overall, there were myriad, and primarily negative impacts correlations between plant diversity and human activities (Coffin 2007; Root‐Bernstein and Svenning 2018).
Environmental disturbances from human activities are also known to induce plant stress responses (Nogués-Bravo et al. 2008) due to altered community composition, hydrology, salinity, substrate compositions in the habitats (Hancock 2002; Herbert et al. 2015). Often, plant species response to these biotic and abiotic stress via production of secondary metabolites, which play a pivotal role in plant defense systems and stress responses (Akula and Ravishankar 2011; Su et al. 2015). Flavonoids are an important class of plant secondary metabolites and have been investigated extensively for their role in plant stress responses. For instance, the increased levels of flavonoids were found to be associated with drought response in Adonis amurensis and A. pseudoamurens (Gao et al. 2020). Moreover, flavonoids with ortho-dihydroxylated B-rings (e.g. catechin gallate, quercetin etc.) were shown to increase in concentration when plants were experiencing...