Marginal effects of rural roads and irrigation canals on woody and non-woody species composition
Across the northern rural regions of Iran, gardens and farmlands are being fragmented into smaller and smaller patches by rural roads network with significant edge effects on plant species composition and abundance. In this study, the presence of different plant species was recorded in ninety 1´1 m plots on nine 100 m transects at the edge of terrene rural roads with irrigation canal and without irrigation canal. Thirty seven plant species were identified in the 9 transects surveyed. Twenty six (70.3%) of those species occurred near the irrigation canal (Transects 2 and 3). Rubus hyrcanus Juz (more than 80% in visually) were observed on transect 3 of the roadside with irrigation canal because of the availability of light and high soil moisture. Ulmus carpinifolia Borkh., Quercus castaneifolia C. A. Mey., Pterocarya fraxinifolia (Lam.) Spach., Parrotia persica C.A.M., Zelkova carpinifolia (pall.) Dipp. and Albizia julibrissin (Willd) Benth were the unique species that were found close to the irrigation canal especially on transect 2. These species are the final survivors of Hyrcanian forests in rural area that were protected from human damages. Plant species richness at the edge of rural road with irrigation canal (37 species) was more than the edge of rural road without irrigation canal (17 species), but the cover value was similar to each other. Punica granatum L. was the most frequent species (more than 80%) on both side of rural road (transect 2 and 3) without irrigation canal.
Key words: Edge, Iran, irrigation canal, plant composition, rural road.