جستجوی مقالات مرتبط با کلیدواژه « festuca ovina » در نشریات گروه « زیست شناسی »

Investigation on the shape of the curve for responses of plant species to environmental gradients is one of the basic topics in the science of rangeland ecology. The objective of this study was investigation on the response of Bromus tomentellus and Festuca ovina species to some environmental variables using the generalized additive model (GAM) in the rangeland of Galandrood watershed in Mazandaran province. Towards this attempt, 153 quadrates of 1m2 along altitudinal gradient were taken. The sampling method was randomized-systematic. In the area sampled, presence of B. tomentellus and F.ovina, altitude, slope and aspect were recorded. Soil samples were taken from 0-20 cm in each quadrate. In each quadrate, soil properties including: pH, N, EC, organic carbon, the percentage of sand, silt and clay were measured. In order to study the shape of response curve in relation to the mentioned variables, GAM model was used with binomial distribution function. The data were analyzed by R ver.3.0.2 computer program. Results showed that altitude was the most important variable affecting the presence of B. tomentellus, While variables such as temperature and slope were the most important factors affecting the presence of F.ovina species. Clay and silt content in the soil were parameters that had significant negative impact on B. tomentellus and F.ovina species distribution. So, with an increase in clay and silt content of the soil, the possibility of the B. tomentellus and F.ovina presence were reduced.

Phenology studying in the rangelands is important for adjustment of grazing programs, optimal and proper utilization from rangelands plants and prevent from early and untimely grazing and recognition of palatability and nutritional value of plant species in different stages. So in order to determine the timing of entry and exit of livestock to and from rangeland this study was carried out in a semi-steppe rangeland in Alamut of Ghazvin province, 100 km North eastern of Ghazvin five years from 2006 to 2010. The two studied wheat species was Bromus tomentellus and Festuca ovina that has moderate palatability for livestock. From each species 10 basic selected. So information of phenology plant noted in 2 stages: growth stage in every 15days and reproductive stage in every 7 days. The time of the start and end of the species growth varied in the different years in this species affected by rainfall and temperature, and length of period in the rainy years is longer than drought periods. Generally their flowering time is the last week of Ordibehesht (April) to the first week of (May) and it lasts for 3 to 6 weeks depending upon the dryness status or wetness position of the year. In the last week of May, we do the seeding phase.