Facing north or south: Does slope aspect impact forest stand characteristics and soil properties in a semiarid trans-Himalayan valley?

Abstract

An understanding of the differences in vegetation and soil characteristics between slope aspects in high altitude semiarid environments is fundamentally important for efficient management of these semi-natural systems; however, few studies have quantified these differences. Here, we analyzed forest stand characteristics, carbon stocks and soil properties of north- and south-facing slopes in a trans-Himalayan semiarid valley. Pinus wallichiana was the dominant and Juniperus indica the co-dominant species in both aspects, whereas Betula utilis and Abies spectabilis were only recorded in north-facing forests. Pinus regenerated in both aspects, whereas Juniperus did not. Carbon stocks did not differ between aspects; 33t/ha in north-facing and 31t/ha in south-facing forests. Similarly, soil properties did not vary between slope aspects, expect for potassium (highest in south-facing slopes). These results suggest that topographic factors affect mountain forests through their direct influence on radiation and moisture, but that human disturbance also plays a significant role affecting vegetation and soil characteristics in a semiarid environment. These natural and anthropogenic factors may play in harmony or in discord with each other. Here, the aridity of the region, parent material and land use history led to less pronounced differences between slope aspects, than commonly found in moister habitats.