Road Impact on Plant Colonization in the Arid Timanfaya National Park

Abstract

Roads have the potential to alter local environmental conditions, such as the availability of water and nutrients, and rapidly create suitable habitats for the establishment of both native and non-native plant species, transforming the ecosystems. This is a challenge in Timanfaya National Park and Los Volcanes Natural Park on Lanzarote Island, protected areas that have experienced primary succession after recent volcanic eruptions. In arid ecosystems, changes in abiotic conditions along roadsides might facilitate colonization and plant growth. We analyzed the effect of roads and road type on plant species composition and richness at a spatiotemporal scale. Vascular plant species were systematically recorded at three distances from the road edge on both sides, across fourteen zones in the wet and dry seasons, for three years. Results showed that there were slight differences on species composition depending on the distance to the road edge, as well as on the zones. Species richness was also determined by the interaction of the position, zones, and season, being higher at the road edge. Furthermore, zones with higher traffic intensity showed a higher presence of both native and non-native species. This study highlights the importance of the awareness about the road impacts on species composition by enhancing the colonization capacity of species while facilitating the entry of invasive ones. Good management practices regarding infrastructures in natural protected areas are crucial for the conservation of their unique flora, landscapes, and natural succession processes.

Keywords: arid protected areas; colonization; primary succession; richness; road-edge effect; species composition.

Figure A1

DCA characterizing species composition according to the season and year under different environmental conditions (a) in the ten zones sampled for three years, and (b) in the case of LZ-67 road with four zones monitored for one year, and (c) in all fourteen zones for one year. Each point on the graph represents a position within a transect for each season and year.

Figure A2

DCA characterizing species composition according to the year under different environmental conditions (a) in the ten zones sampled for three years, and (b) in all fourteen zones for one year. In the case of the LZ-67 road, there is only one type of road, so there is no analysis. Each point on the graph represents a position within a transect for each season and year.

Figure 1

DCA characterizing species composition according to zones under different environmental conditions in (a) the ten zones sampled for three years, and (b) the case of the LZ-67 road with four zones monitored for one year, and (c) all fourteen zones for one year. Each point on the graph represents a position within a transect for each season and year.

Figure 2

DCA based on species composition according to the position in respect to the road border in (a) the ten zones sampled for three years, (b) the case of LZ-67 road with four zones monitored for one year, and (c) all fourteen zones for one year. Each point on the graph represents a position within a transect for each season and year.

Figure 3

(a) Effect of the position (distance to the road: border, middle, or interior) on the number of species, (b) effect of the season (winter, summer) on the number of the species, (c) and effect of zones (Altos Timanfaya, Calderas Quemadas, Caldereta Riscada, Islote, Manto Virgen, Mazo, Montaña Rajada, Taro, Tremesana, Valle Tranquilidad, Yaiza, Echadero Camellos, Taro 1, and Centro Visitantes) following linear mixed-effect models with position, zone, season, and transect as random factors and Tukey post hoc test, p < 0.05. Different letters indicate significant differences between groups.

Figure 4

(a) Effect of the endemicity (*NS: endemic species; N: the rest of the native species; II: invasive introduced species; I: the rest of the introduced species;) on the number of species on dataset 1: Altos Timanfaya, Calderas Quemadas, Caldereta Riscada, Islote, Manto Virgen, Mazo, Montaña Rajada, Taro, Tremesana, and Valle Tranquilidad (only using data from the first and last winters); (b) Effect of the endemicity (*NS: endemic species; N: the rest of the native species; II: invasive introduced species; I: the rest of the introduced species) on the number of species on dataset 2: Yaiza, Echadero Camellos, Taro 1, and Centro Visitantes, following linear mixed-effect models with position, zone, and transect as random factors and Tukey post hoc test, p < 0.05. We only analyzed differences in endemicity within each specific time and changes over time within the same dataset. Different small letters indicate significant differences between time, and capital letters show significant differences in endemicity.

Figure 4

(a) Effect of the endemicity (*NS: endemic species; N: the rest of the native species; II: invasive introduced species; I: the rest of the introduced species;) on the number of species on dataset 1: Altos Timanfaya, Calderas Quemadas, Caldereta Riscada, Islote, Manto Virgen, Mazo, Montaña Rajada, Taro, Tremesana, and Valle Tranquilidad (only using data from the first and last winters); (b) Effect of the endemicity (*NS: endemic species; N: the rest of the native species; II: invasive introduced species; I: the rest of the introduced species) on the number of species on dataset 2: Yaiza, Echadero Camellos, Taro 1, and Centro Visitantes, following linear mixed-effect models with position, zone, and transect as random factors and Tukey post hoc test, p < 0.05. We only analyzed differences in endemicity within each specific time and changes over time within the same dataset. Different small letters indicate significant differences between time, and capital letters show significant differences in endemicity.

Figure 5

Location of the roads and trails sampled. For three years, we monitored the roads and trails colored in dark green. The light green transects correspond to each of the transects. The dark blue road with the light blue transects were analyzed for one year.

Figure 6

Transect sampling design. The six transects of one section are shown according to the distance from the roadside (0–1 m; 2–3 m; 4–5 m) on both the right and left sides of the road (three transects at each side).