ABSTRACT
Ephedra major and Hymenocrater calycinus are among the bushy and shrub plants resisting to drought conditions. These species have a very important role in soil protection, medicinal and forage value in arid areas. This research was conducted in order to investigate the distance indices to determine the species spatial distribution pattern of Ephedra major and Hymenocrater calycinus in the southwest rangelands of Bojnord. Vegetation sampling was done by systematic-random method, therefore, 5 transects of 100 meters were determined in each working unit. To collect information from the habitat, the nearest species and nearest neighbor distance method was used. Evaluation was done by using distance indices of Eberhart, Hinez, Pielou, T-square, Hopkins, Holgate and Johnson and Zimmer. The findings showed that most of the investigated indices accepted the clumped distribution pattern, so it can be said that the spatial distribution pattern of Ephedra major and Hymenocrater calycinus is clumped. Results showed the uniform pattern of Holgate and Pielou indices for Ephedra major species and Hopkins, Holgate and Pielou indices for Hymenocrater calycinus species. In general, the use of plant distribution patterns plays a significant role in choosing the appropriate sampling method, ecological interpretations and providing management approaches.

Key words: Ephedra major, Distribution pattern, Distance indices, Hymenocrater calycinus, Rangelands.










EXTENDED ABSTRACT

Introduction
Ephedra major is dioecious and evergreen bushy and shrubs growing to 20-200 cm tall; woody stems well developed, erect or mostly procumbent, thick; herbaceous branchlets are slender, striate, smooth, bluish-green or grayish-green, 1-1.5 mm in diameter, internodes short, 1-3 cm × 1-1.5 mm, finely furrowed. Leaves are opposite, leathery, greenish or brownish, 1.5-3 mm, connate for ca. 3/4 their length, free part bluntly triangular. Female cones
usually opposite at nodes, shortly pedunculate,
elongate-ovoid or ovoid at maturity, 8-10 × 4-5 mm;
bracts in 3 pairs, apical pair connate for ca. 2/3 their
length, red and fleshy at maturity; integument tube to 2
mm, straight or slightly curved, slightly exerted. Seeds
usually 1, elongate-ovoid, 5-7 × 2.5-3 mm and male
cones are sessile, subglobose, 4-5 mm long. Ephedra has long been used as a medicinal plant to reduce fever, initiate perspiration, manage asthma, and treat coughing. Hymenocrater calycinus (Boiss.) Benth. is one of medicinal herbs in Lamiaceae family of Iran and it is growing natural habitats in the north east of Iran. In traditional medicine, this plant use for diuretic, flu treatment, antifungal, antibacterial and antioxidant. Knowledge of the spatial distribution pattern of plant communities is essential for understanding many questions in ecology and management of natural ecosystems. Ephedra major and Hymenocrater calycinus are among plants resistant to drought conditions and play a very important role in soil protection, medicinal and fodder value in dry areas. This survey was conducted in order to investigate the distance indices to determine the distribution pattern of Ephedra major and Hymenocrater calycinus species in the mountainous shrub rangelands in the southwest of Bojnord with an area of about 9300 hectares.
Materials and Methods
Vegetation sampling was done by systematic-random method, therefore, 5 transects of 100 meters were determined in each work unit (north and south slopes). To collect data from the site, the nearest species and nearest neighbor distance method was used. Evaluation was done using Eberhart, Hinez, Pielou, T-square, Hopkins, Holgate and Johnson and Zimmer distance indices.
Results and Discussion
The findings showed that among the distance indices, Eberhart, Hopkins, Johnson and Zimmer, T-square and Hinez indices with values of 2.205, 0.53, 6.178, 0.653 and 2.603 respectively for Ephedra major species and Eberhart, Johnson and Zimmer, T-square and Hinez indices with the values of 1.687, 4.632, 0.547 and 1.643, respectively, for Hymenocrater calycinus species, the pattern of distribution in the studied habitat is clumped. The results showed that the indices of Holgate and Pillow with the values of -0.473 and 0.374 respectively and Hopkins, Holgate and Pillow with the values of 0.43, -0.485 and 0.798 respectively for Ephedra major and Hymenocrater calycinus species showed a uniform distribution pattern. Because most of the examined indicators accepted the clumped pattern, therefore, for the management plans of the region using these plants, the clumped pattern must be considered. Generaly, the use of spatial patterns of plants in providing management solutions can contain an important point for those involved in the executive departments of natural ecosystems renovation that successful plans for the renovation and improvement of rangelands follow the natural patterns which are usually clustereds.
Conclusion
In conclusion in the investigate, the results showed that most of the surveyed indicators accepted the clumped distribution pattern, so it can be said that the spatial distribution pattern of Ephedra major and Hymenocrater calycinus is clumped in the survey sites. Based on the findings obtained from the study of other researchers, the clumped type is the most commonly observed plants spatial pattern in natural ecosystems. Spatial patterns of plants play a significant role in recognizing and solving ecological problems and introducing management strategies. Distribution patterns are of great importance in studying the formation of plant communities, and the results of the estimation of plant factors may be affected by the distribution pattern. By studying the distribution pattern in plant communities, one can gain a lot of knowledge about the uniformity and non-uniformity of the habitat, the type of reproduction and reproduction, biodiversity, plant spread, competition, and better protection of ecosystems. The distribution pattern of plant species also affects the sampling method and certainly the number of samples required. It should be noted that the type of dominant plant species in each habitat and the specific conditions of the plants under study, plants with different densities and with different distribution patterns can result in different findings, therefore, choosing a suitable index for evaluating the plants of the habitat is of great importance and should be given priority. The findings of this study can contain an important point for stakeholders and managers of executive departments for the restoration of natural ecosystems, which is emphasized by this study. Successful plans for the restoration and improvement of natural resources follow natural patterns that are usually cumulative.