Deljouei Azade, Abdi Ehsan, Marcantonio Matteo, Majnounian Baris, Amici Valerio, Sohrabi Hormoz
Department of Forestry and Forest Economics, University of Tehran, Tehran, Iran.
Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, USA.
Environ Monit Assess. 2017 Aug;189(8):392. doi: 10.1007/s10661-017-6105-1. Epub 2017 Jul 13.
Forest roads alter the biotic and abiotic components of ecosystems, modifying temperature, humidity, wind speed, and light availability that, in turn, cause changes in plant community composition and diversity. We aim at investigating and comparing the diversity of herbaceous species along main and secondary forest roads in a temperate-managed hornbeam-beech forest, north of Iran. Sixteen transects along main and secondary forest roads were established (eight transects along main roads and eight along secondary roads). To eliminate the effect of forest type, all transects were located in Carpinetum-Fagetum forests, the dominant forest type in the study area. The total length of each transect was 200 m (100 m toward up slope and 100 m toward down slope), and plots were established along it at different distances from road edge. The diversity of herbaceous plant species was calculated in each plot using Shannon-Wiener index, species richness, and Pielou's index. The results showed that diversity index decreased when distance from road edge increases. This decreasing trend continued up to 60 m from forest road margin, and after this threshold, the index slightly increased. Depending on the type of road (main or secondary) as well as cut or fill slopes, the area showing a statistical different plant composition and diversity measured through Shannon-Wiener, species richness, and Pielou's index is up to 10 m. The length depth of the road edge effect found in main and secondary forest roads was small, but it could have cumulative effects on forest microclimate and forest-associated biota at the island scale. Forest managers should account for the effect of road buildings on plant communities.
林间道路改变了生态系统的生物和非生物成分，影响了温度、湿度、风速和光照条件，进而导致植物群落组成和多样性发生变化。我们旨在调查和比较伊朗北部温带管理的鹅耳枥-山毛榉林中主要和次要林间道路沿线草本植物的多样性。在主要和次要林间道路沿线设置了16个样带（8个样带沿着主要道路，8个沿着次要道路）。为消除森林类型的影响，所有样带均位于研究区域内占主导地位的森林类型——栎林-山毛榉林中。每个样带的总长度为200米（上坡方向100米，下坡方向100米），并沿着样带在距道路边缘不同距离处设置样地。使用香农-维纳指数、物种丰富度和皮洛指数计算每个样地中草本植物物种的多样性。结果表明，随着距道路边缘距离的增加，多样性指数降低。这种下降趋势一直持续到距林道边缘60米处，超过这个阈值后，指数略有上升。根据道路类型（主要或次要）以及挖方或填方边坡的不同，通过香农-维纳指数、物种丰富度和皮洛指数测量的显示出统计学上不同植物组成和多样性的区域可达10米。在主要和次要林间道路中发现的道路边缘效应的长度深度较小，但在岛屿尺度上可能会对森林小气候和与森林相关的生物群产生累积影响。森林管理者应考虑道路建设对植物群落的影响。
