Effects of Shrub Canopy on the Microclimate and Soil Properties of Steppe Rangeland
Authors
Abstract
In arid and semi-arid ecosystems, shrubs may act as fertility islands but their
effect may vary depending on their morphology and ecological impacts. This research was
aimed to study effect of three shrubs Scariola orientalis, Astragalus heratensis, and Rosa
persica on soil properties and on the microclimate conditions (temperature, luminance, and
soil moisture) of their understory in the steppe rangelands of Kakhek Gonabad, Iran. Along
50-m transects, flexible plot sizes were selected to measure the microclimate factors of
understory species and the open spaces next to the shrubs based on the canopy diameters of
each intercepted shrubs. Soil samples were taken from understory of shrubs. The
microclimatic factors of understory and open spaces were compared using paired-t test.
The soil properties were analyzed under 3 shrubs and open spaces and then comparison
were made using Duncan‟s test. The results showed that temperature and luminance
intensity were significantly lower in understory than the open spaces (p<0.05). Soil depth
moistures (15-55 cm) were higher in understory than the open space while soil surface
moistures (0-10 cm) did not vary. Among the investigated shrubs, Astragalus heratensis
had the greatest facilitation effect on microclimatic factors. The soil criteria of EC (0.32
mS/cm), organic matter (1.6%), and nitrogen (0.08%) were significantly higher in
understory of Astragalus heratensis than in the open space (0.15 mS/cm, 0.39%, and
0.028%), respectively. These effects can be related to the wider canopy cover, greater
stature, and possibly nitrogen fixation for Astragalus heratensis.
