Ignacio Mola

Use of restoration plantings to enchance bird seed dispersal at the roadside: failures and prospects

AbstractPlantings are commonly used in roadside reclamation for ornamental purposes and for increasing slope stability and road safety. However, the role of these plantings in restoring ecological processes, such as seed dispersal, has received little attention. We carried out a study to assess the potential role of plantings on roadside embankments to attract frugivorous birds and to enhance seed dispersal mediated by birds from the surrounding landscape. We examined: (1) bird species richness and abundance; (2) patterns of avian spatial distribution within embankments and (3) seed dispersal mediated by birds. Bird richness and abundance did not differ between embankments with and without plantings. However, birds were not distributed randomly within embankments, with levels of species richness and abundance for facultative frugivorous between 4.8–8 times higher in areas closer to plantings. An analysis of bird droppings showed that birds only dispersed seeds of the planted species since no seeds of wood...

Roadsides: An opportunity for biodiversity conservation

Questions How do roadsides interact with patches of natural vegetation in shaping perennial plant communities in fragmented agricultural areas? Are the observed differences due to the type of roadside (i.e., roadcuts, embankments or road verges) or are there other factors driving community structure and composition? Location Stretch of motorway A3 and its surrounding area, in central Spain. Methods We analysed the variation in perennial plant species composition and diversity among 92 plots (400 m2). The plots were located in five different environmental scenarios, three of them in a fragmented landscape (patches of natural vegetation, embankments, and roadcuts) and two in an unfragmented landscape (natural vegetation and road verges). In each plot, the cover of each perennial plant species and eight soil variables were assessed. We used phi coefficient of correlation to determine the scenario preferences of each species, Kruskal-Wallis tests to compare the soil variables between landscape scenarios and eight descriptive variables of the community, and RDA and partial RDA analysis to evaluate the relative importance of the type of environmental scenario on the floristic community. Results We identified 130 species, with only 16 species never appearing on roadsides. Perennial total cover, species richness, inverse Simpsons index and number of protected species showed no significant differences between the five scenarios considered. In contrast, the number of nutrient-demanding species and restricted-range diversity showed lower values in natural vegetation plots. Soil variables and the type of scenario together explained 28.5% of the species composition variation. Of this percentage, 6.8% was explained by soil variables, 12.1% by the type of scenario and 10.0% of the variation was shared between the two datasets. Conclusions Our results show that almost all perennial species occurring in natural vegetation patches were also able to reach and settle in the roadsides. However, soil conditions and other specific roadside variables generate different plant communities. In spite of the differences found between the perennial plant community of roadsides and their surrounding area, roadsides are excellent reservoirs of biodiversity. This article is protected by copyright. All rights reserved.

Local plant responses to global problems: Dactylis glomerata responses to different traffic pollutants on roadsides

The growing number of road vehicles is a major source of regional and global atmospheric pollution increasing concentrations of CO2 in the air, and levels of metals in air and soil. Nevertheless, the effects of these pollutants on plants growing at roadsides are poorly documented. We carried out an observational study of unmanipulated plants growing by the road, to identify the morpho-physiological responses in a perennial grass Dactylis glomerata. Firstly, we wanted to know the general effect of traffic intensity and ambient CO2 and its interactions on different plant traits. Accordingly, we analyzed the photosynthetic response by field A/Ci Response Curves, SLA, pigment pools, foliar nitrogen, carbohydrates and morphological traits in plants at three distances to the road. Secondly, we wanted to know if Dactylis glomerata plants can accumulate metals present on the roadside (Pb, Zn, Cu, and Sr) in their tissues and rhizosphere, and the effect of these metals on morphological traits. The MANCOVA whole model results shown: 1) a significant effect of road ambient CO2 concentration on morphological traits (not affected by traffic intensity, P interaction CO2 x traffic intensity>0.05), that was mainly driven by a significant negative relationship between the inflorescence number and ambient CO2; 2) a positive and significant relationship between ambient CO2 and the starch content in leaves (unaffected by traffic intensity); 3) a reduction in Jmax (electron transport rate) at high traffic intensity. These lines of evidences suggest a decreased photosynthetic capacity due to high traffic intensity and high levels of ambient CO2. In addition, Pb, Cu, Zn and Sr were detected in Dactylis glomerata tissues, and Cu accumulated in roots. Finally, we observed that Dactylis glomerata individuals growing at the roadside under high levels of CO2 and in the presence of metal pollutants, reduced their production of inflorescences.