Different components of plant diversity suggest the protection of a large area for the conservation of a riparian ecosystem

Abstract

Riparian ecosystems host an high level of biodiversity but anthropic activities have deeply altered their naturalness and functionality. The present study was carried out in a protected area along a recently regulated tract of the upper River Tiber (Tuscany, central Italy). The study's aim is to explore different components of plant diversity (species richness, species composition, β-diversity) in the riparian habitats to determine the most relevant conservation issues. Twelve transects were allocated along the riparian zone and a stratified random sampling was performed on the habitat detected along the transects with 184 plots of 1 x 1 m. Species richness was analysed by the use of set of species-richness estimators. The different patterns of plant diversity were analysed by NMDS, Indicator Species Analysis and SDR with symplex analysis. Five habitat types were detected in the study area. Three well-represented habitats (riparian woodlands, shrublands and dry bars) showed a higher number of species; flooded banks and marshlands were much less common and were also less species rich. Species composition and indicator species analysis showed however that marshlands were the richest in taxa having high conservation value and in indicator species. The habitats differed greatly in species composition; β-diversity analysis showed a low number of shared species between the habitats. High values of species replacement and low similarity values were recorded between the plots within the habitats. The study shows some differences between quantitative and qualitative patterns of biodiversity in the study area. The results suggest that to maintain habitat species diversity, the best conservation strategy for the study area is to protect as large an area as possible

Cross Taxon Congruence Between Lichens and Vascular Plants in a Riparian Ecosystem

“…This area lays on alluvial lacustrine-fluvial deposits and is altered by human activities, such as gravel mines, which cause strong modifications to the original landscape. The construction of the dam and other infrastructures modified the track of Tiber several times [46]. The river regulation influenced the stream flux, leading to the disappearance of seasonal water availability, with consequent reduction of solid carriage due to rapid sedimentation [46].…”

“…The construction of the dam and other infrastructures modified the track of Tiber several times [46]. The river regulation influenced the stream flux, leading to the disappearance of seasonal water availability, with consequent reduction of solid carriage due to rapid sedimentation [46]. Furthermore, the dam deep water temperature is a few degrees lower than in natural conditions (approximately 7.7 • C vs. 12 • C), reaching its natural temperature only some kilometers downstream [46].…”

“…The river regulation influenced the stream flux, leading to the disappearance of seasonal water availability, with consequent reduction of solid carriage due to rapid sedimentation [46]. Furthermore, the dam deep water temperature is a few degrees lower than in natural conditions (approximately 7.7 • C vs. 12 • C), reaching its natural temperature only some kilometers downstream [46]. Even in the presence of these disturbances, hygrophilous vegetation shows a high level of conservation and naturalistic value [47] and the study area has been included among the protected areas in the Region (ANPIL, Protected Natural Area of Local Interest).…”

“…Even in the presence of these disturbances, hygrophilous vegetation shows a high level of conservation and naturalistic value [47] and the study area has been included among the protected areas in the Region (ANPIL, Protected Natural Area of Local Interest). Species richness and the composition of plant and lichen communities were surveyed along 12 transects (defined as "primary sampling units" following Lastrucci et al [46]), each 5 m wide and with a variable length according to the width of the riparian zone (see Figure 1). These were randomly displaced along the riverside (6 on the left bank and 6 on the right one) and they were placed at 250 m from each other in order to avoid the effect of spatial autocorrelation.…”

“…The following classification was adopted to characterize the sampled habitats (strata, see [46] for details): On the basis of the total area occupied by each habitat, a proportional number of randomly selected squared plots of 1 m 2 were sampled as follows: If the habitat area was lower than 25 m 2 , three plots were sampled; when the habitat area was greater than 25 m 2 , two more plots were added for each increase of 25 m 2 (e.g., for a habitat surface of 75 m 2 , seven plots were displaced) for a total of 188 plots (Table 1). Presence and percentage coverages of vascular plants (proportion of the area Species richness and the composition of plant and lichen communities were surveyed along 12 transects (defined as "primary sampling units" following Lastrucci et al [46]), each 5 m wide and with a variable length according to the width of the riparian zone (see Figure 1). These were randomly displaced along the riverside (6 on the left bank and 6 on the right one) and they were placed at 250 m from each other in order to avoid the effect of spatial autocorrelation.…”