Local topoclimate effect on short-term cutslope reclamation success

Abstract

Cutslopes created by earthworks are a challenge for restoration practitioners. A clear and ecological understanding of environmental constraints is a requirement for successful revegetation. This study was conducted to evaluate the effects of solar radiation exposure (SRE) on short-term plant establishment on road cutslopes after hydroseeding herbaceous plants. The study site is located in gneissic hills (Vigo, Northwest Spain) that were excavated by roadworks. Cutslope steepness is higher than 50° and three aspects (SW, S and SE) were used as SRE treatments. Neither hardness nor surface roughness were significantly different among aspects. There were small significant differences in irradiance among aspects, however, the daily peak had a delay from SE to SW. This irradiance pattern probably accounts for a trend in temperature increase and moisture decrease along the gradient SE–SW–S. Water availability for plants is likely to decrease along this gradient, S being the driest topoclimate. A significant coincident trend of decrease in plant density, plant biomass, total plant cover and seedling development was observed along the SE–SW–S gradient. Moreover, seedling density was extremely low in all aspects, demonstrating the prevailing strong environmental constraints of the site. SRE may affect the early establishment and development of herbaceous plants at cutslopes. Therefore, a good project design for cutslope reclamation should adequately consider local topoclimatic conditions.