Evaluarea efectului de margine generat de drumuri forestiere, prin variabile microclimatice selectate, în păduri de foioase din zona deluroasă a Republicii Moldova

Abstract

This study characterizes and analyzes the edge effects generated by a forest road as the variation of climate factors such as air temperature, relative humidity and vapor pressure deficit, in broadleaved mixed forests, located in the hilly area of the Republic of Moldova. In order to monitor the climatic parameters (temperature and relative humidity), two transects were placed in the field. Two dataloggers were placed on the first transect (0 and 50 m from the roadside), while on the second one were used 4 data collectors (0, 18, 36, 46 m - relative to the road edge). Data collected over a period of one year, was used to calculate vapor pressure deficit and to compare the values with the data from the nearest weather station, for the same time period. Both, the monthly variation of climate factors between the forest edge and interior, as well as the hourly variation of the measured parameters in a critical period (2-6 August 2017) were analyzed in this study. The analyzed variables showed very small, sometimes inexistent differences, between the edge and forest interior. Compared to the values taken from the weather station, the average daily and nocturnal temperatures were lower throughout the year in the study area. The negative differences were recorded in August, reaching up to 4.2 °C during the night. At yearly scale, the relative humidity of the air had, in general, higher values into the forest, with the largest differences also recorded in August. The most prominent difference between the mean values of vapor pressure deficit specific to the weather station and those recorded at the edge, was reached in August and ranged from 0.55 to 0.69 kPa. In the analyzed critical days, the average air temperature was lower at the edge, compared to the forest interior throughout the day. Also, for the critical days taken into analysis, the differences between the values of parameters sampled at different locations and those sampled at the forest interior were statistically insignificant. The temperature showed a downward trend only up to a distance of 36 m, a trend that can be interpreted only up to that distance since the last sampling point, which showed an increase in temperature, was most likely to be influenced by the canopy gaps in its surrounding area. Relative air humidity had an increasing trend from the edge to forest interior, and the dynamics of the vapor pressure deficit was influenced, along the transect, by the specific dynamics of temperature and relative humidity. Conclusions: Even though the presence of the road-induced edge effect has not been statistically significant, more research should be undertaken to be able to formulate recommendations on the design and/or construction of forest roads.