Effects of topography and woody plant canopy cover on near-ground solar radiation: Relevant energy inputs for ecohydrology and hydropedology

The emerging interdisciplinary approaches of ecohydrology and hydropedology are sensitive to variation in soil-surface energy inputs, which are primarily modified by topography and woody plant canopies. Yet a synthesis of the interactive effects of these two modification types is lacking. We systematically estimated near-ground surface solar radiation inputs as modified by key attributes of topography (aspect and slope) and tree cover (degree of openness) using solar radiation modeling based on hemispherical photographs. For south aspects, reductions in annual transmission were dominated by canopy cover rather than topography, even when canopy cover was low, whereas for north aspects, canopy effects dominated the reduction in annual transmission for slopes of up to 10° at low canopy cover and up to 30° at high canopy cover. Our results provide a synthetic perspective of the nonlinear, interactive, and temporally dependent effects of slope, aspect, and amount of canopy cover on near-ground solar radiation.