There is strong pressure to embrace indicators for practical goals such as nature conservation and management and to evaluate the restoration success, but the selection of appropriate indicators is not straightforward. In addition, the grain and the type of data collected and data transformation adopted can influence restoration monitoring results. In this paper, we assessed the effect of changing indicator, grain size (i.e., plot dimension) and data transformation in discriminating different mapped plant communities, relying on vascular plant composition data. We considered flora entities at different taxonomic scales of resolution as indicators and used biological forms such as life forms, growth forms and a combination of the two types, i.e., life and growth forms, as rough plant traits. We also analysed the contribution of species as indicators of the different land cover classes by performing an Indicator Species Analysis. We evaluated the effect of changing indicator (taxonomic resolution, life and growth forms and indicator species), grain size and data transformation using permutational multivariate analysis of variance on cover data expressed in percentages and as simple presence/absence. Our results demonstrated that indicators such as taxonomic resolution and biological forms have partial success in discriminating between plant communities, only for the analysis performed on presence/absence data, and that the effects of changing indicator varied depending on the data transformation used. On the contrary, indicator species are coherently effective and changing the grain size has a moderate influence on their ability to discriminate among the habitat types investigated. Hence, indicator species emerged as a promising tool in restoration monitoring. Although indicators are not supposed to substitute comprehensive surveys of vegetation, their use can help redirect considerable time, resources and expertise to more replication and better sampling design.
Authors:E. Santi, E. Mari, S. Piazzini, M. Renzi, G. Bacaro and S. Maccherini
Farmland ponds represent habitats with a high conservation value that make a significant contribution to regional biodiversity. Understanding the influence of plant species composition and environmental variables in driving variations in animal species composition in ponds is an important issue in the fields of ecological research and conservation biology. Using variance partitioning techniques to quantify independent effects, we examined how plant species composition, local-landscape configuration and physicochemical variables interact in influencing aquatic insect and amphibian community composition. The ponds investigated in this study were located in the Site of Community Importance — Special Protected Area (Natura 2000 Network) “Monte Labbro — Alta Valle dell’Albegna” (Tuscany, central Italy). Our results showed that: (i) plant community composition (such as Carex hirta, Glicerya fluitans, Potamogeton natans, Typha latifolia) is a good predictor for amphibian but not for aquatic insect species composition; (ii) aquatic insect species composition was more strongly affected by the landscape context, whereas for amphibians the local characteristics of the ponds were determining; (iii) the physicochemical context is a poor predictor for these animal taxa; (iv) lastly, and notably, the explanatory variables explained a high proportion of the total variation in amphibian and aquatic insect species composition. Our results have important implications with respect to the creation of new ponds, which should preferentially take place close to semi-natural grasslands and other wetlands, in order to maintain greater connectivity, and away from urban areas. Moreover, larger ponds are preferable for the preservation of pond biodiversity. The management and conservation of ponds is necessary to ensure the protection of habitats, the survival of individual species and overall pond biodiversity.
Authors:G. Bacaro, S. Maccherini, A. Chiarucci, A. Jentsch, D. Rocchini, D. Torri, M. Gioria, E. Tordoni, S. Martellos, A. Altobelli, R. Otto, C. G. Escudero, S. Fernández-Lugo, J. M. Fernández-Palacios and J. R. Arévalo
Invasion by alien plant species may be rapid and aggressive, causing erosion of local biodiversity. This is particularly true for islands, where natural and anthropogenic corridors promote the rapid spread of invasive plants. Although evidence shows that corridors may facilitate plant invasions, the question of how their importance in the spread of alien species varies along environmental gradients deserves more attention. Here, we addressed this issue by examining diversity patterns (species richness of endemic, native and alien species) along and across roads, along an elevation gradient from sea-level up to 2050 m a.s.l. in Tenerife (Canary Islands, Spain), at multiple spatial scales. Species richness was assessed using a multi-scale sampling design consisting of 59 T-transects of 150 m × 2 m, along three major roads each placed over the whole elevation gradient. Each transect was composed of three sections of five plots each: Section 1 was located on the road edges, Section 2 at intermediate distance, and Section 3 far from the road edge, the latter representing the “native community” less affected by road-specific disturbance. The effect of elevation and distance from roadsides was evaluated for the three groups of species (endemic, native and alien species), using parametric and non-parametric regression analyses as well as additive diversity partitioning. Differences among roads explained the majority of the variation in alien species richness and composition. Patterns in alien species richness were also affected by elevation, with a decline in richness with increasing elevation and no alien species recorded at high elevations. Elevation was the most important factor determining patterns in endemic and native species. These findings confirm that climate filtering reflected in varying patterns along elevational gradients is an important determinant of the richness of alien species (which are not adapted to high elevations), while anthropogenic pressures may explain the richness of alien species at low elevation.