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to development instability, although the main value was slightly higher in the flooded habitat (Table 2; Fig.5).
The variation among individual leaves (symmetric components) showed a higher value (between 60 and 70%) relative to the variation of the position of the landmarks on both sides of a leaf (asymmetric component) (about 40%) for both habitats (Fig. 4).
In the visual presentation (scatterplots) of discriminant analysis of leaf shape derived from Canonical Variance Analyzes (CV), the first canonical variates (CV1) indicated 39.67% variance while the second (CV2) showed 23.47% variance (Fig. 5).
Plant ecology and evolutionary biology studies focus on exploring the rules of plants organs development, growth and morphology diversity outputs, with temporal and spatial organization, which are under control of genetic structures closely correlated with habitat ecological characteristics (Lin et al., 2016, DeWoody et al., 2015).
In this study we used the plants present in a given study areas (flooded and non-flooded) as a passive model of biomonitoring (Nali and Lorenzini, 2007). Anthropogenic activities induced fast climate changes. Flooding is a common natural disasters which increases impacts on ecosystem as a whole (Herzog and Pedersen, 2014). The tree survival, growth change in flooding areas, and the degree of damage depends on the ontogenetic stage of the tree characteristics (active growth or dormant), tolerance and the flood itself (time of the year and duration). Flood-stressed trees exibit a range of symptoms including chlorosis, defoliation, reduced leaf size and shoot growth (Baughman, 2010).
The significant differences between habitats (flooding and not flooding) were observed in terms of the leaf centroid size (geometic size) and shape (Table 1). The changes in leaf size and especially in the shape are considered to have functional significance related to different natural conditions (Zhuang et al., 2011). Rood et al. (2003) stated that flooding dramatically reduced leaf size and slightly decreased some foliar gas exchange characteristic in poplar due to oxygen deficiency in the roots. The size, shape and biomechanical properties of its root and its specific aerial structures are well adapted to cope with these stressed inducing conditions. However, the poplar species are known its tolerance of fluctuating hydrological conditions, but P. nigra cannot stand flooding which last longer than 60 days (Herpka, 1963). The physiology, morphology and biomechanics of