Effects of roads on understory plant communities in a broadleaved forest in Hyrcanian zone

Abstract

This study was conducted to assess the effect of forest road as a corridor on local biodiversity. For this purpose, 10 segments in a 10 year-old road were selected in Neka-Zalemrood forest in Hyrcanian zone. At each of the segments, we established two 100-m transects perpendicular to the road centre line, within which we sampled three macroplots of an area 400 m<sup>2</sup>. In each macroplot, nine quadrant microplots 2 × 2 m in size were set up for regenerated tree species and herbaceous plant survey. Chemical and physical parameters of soil were measured in laboratory. Results indicated that thirty-six herbaceous species and 13 regenerated tree species were recorded within the area of 100 m from the road verge. At the different distances from the road verge and both down and up-slope, the ground cover of Carex sylvatica and Rubus caesius L. as well as regeneration density of Carpinus betulus L. were higher compared to other species. Menhenick, Margalef, Shannon and Simpson indices were higher at the distance of 0–20 m than at the distances of 40–60 m and 80–100 m. Camargo and Smith-Wilson indices decreased when increasing distance to the road. These results are expected to provide critical information for decision makers and land managers for managing plant species and maintaining the integrity of biological communities.  

Effects of forest roads on vegetation biodiversity and soil characteristics in Hyrcanian forests

“…Soil can be a factor in increasing the frequency of herbaceous cover on the side of the road. The reason for the presence and abundance of many herbaceous species is due to greater access to light or soil nitrogen, which affects the growth, composition and diversity of species (Karim and Mallik 2008, Avon et al 2010, Lotfalian et al 2012, Boston 2016, Deljouei et al 2018, Fallahchai et al 2018, Lisboa et al 2022). Soil is a parameter that is greatly affected by road construction and many of its characteristics can be changed.…”

“…The available TP, pH, SM, N, P, K and Ca parameters had the greatest effect on diversity and richness. Lotfalian et al (2012) showed that soil organic carbon, silt, moisture, lime, Ca and clay have no effect on biodiversity indicators. The results of the study by Karim and Mallik (2008) showed that the lowest amount of moisture and organic matter and the highest BD are seen on the shoulders of the roads.…”

“…In the science of forest management, forest roads are needed for various activities such as wildlife conservation, tourism, reforestation, forestry and harvesting, fighting against pests and diseases, and fighting fires (Delgado et al 2007, Haider et al 2018, Rahbarisisakht et al 2021, Lisboa et al 2022). Although the positive effects of forest roads are undeniable, it should not be ignored that roads cause the destruction of forest, which will have certain consequences (Deljouei et al 2018, Picchio et al 2018, Lotfalian et al 2012). Among these interferences are the increases in the death of animals due to the construction of roads or collisions with vehicles, changing the landscape, fragmenting the habitat and reducing its quality (Karim and Mallik 2008, Delgado et al 2013, Marcantonio et al 2013, Deljouei et al 2017).…”

“…They are the primary ways for the spread of new species into managed stands and have an effect on changing the richness and diversity of plants at the stand level. Many studies have shown that roadside plant composition is altered in favor of non‐native and light‐friendly species and community composition is significantly changed (Karim and Mallik 2008, Lotfalian et al 2012, Li et al 2022). On the other hand, the taking out of wood from the roads causes soil erosion and it harms the regeneration of trees.…”

“…On the other hand, the taking out of wood from the roads causes soil erosion and it harms the regeneration of trees. Meanwhile, reducing damage to the remaining forest stand and soil is one of the goals of forest management (Lotfalian et al 2012, Deljouei et al 2018, Zamani et al 2019). Basically, forest vegetation is sensitive to the physical characteristics of the soil (Zhou et al 2020, Rahbarisisakht et al 2021).…”