Journal of Rangeland

Phonological and morphological responses of three rangeland grasses Stipa turkestanica, Melica persica and Elymus elongantus were studied to the understory soil moisture reduction and temperature increase, within a growth season in Dehbar rangelands, Binalud, northeast Iran. Phenological events were recorded by doing field visits every 10-14 days. Soil moisture and temperature, leaf moisture and air temperature were measured under canopy of the grass species, five times during the growing season. Native species M. persica  and S. turkestanica started their flowering in Mid-May and finished the seed ripening stage at Mid-June. Introduced E. elongatus started its flowering stage from early May and finished the seed ripening stage at mid-July. The C₄ photosynthetic pathway and fewer leaf and stems led to a lower reduction in leaf moisture of M. persica. In contrast, a dense canopy for E. elongatus led to soil moisture conservation. From beginning till the end of growth season, 90 and 7 percent moisture reductions were respectively found in leaves and understory soil of the studied species. For the same time, 10 and 15 percent increases were respectively found in the understory soil and air temperatures.  Under the intense summer drought, higher reduction in leaf length and number was found for M. persica (40%) but lower value (12%) for E. elongatus. According to our findings, the introduced grass E. elongatus can be a suitable species for Dehbar rangelands both in terms of forage production and drought resistance. Proper time for livestock grazing from all three species in Dehbar ragelands is suggested from late May till early July.