Journal of Rangeland
Year:2008 | Volume:2 | Issue:3|Papers Count:9

In this research, the effects of water point distances on vegetation parameters were analyzed using MANOVA and ANOVA. In each of two water points, 8 transects of 2 km were established randomly, and each 100-m of one transect was considered as treatment. In each treatment, four plots of 4_m2 were sampled for measurements of canopy coverage, species richness, and density. Vegetation parameters of canopy coverage, richness, and density were significant for all treatments (p<0.01). Using ANOVA, density and species richness were significant (p<0.01), and canopy coverage was not significant (p>0.0 1). Although MANOVA was significant for vegetation parameters, but the results of discriminate analysis was not consistent with it. This was due to spare vegetation around water points, which caused high value for Wilks' lambda index. It can be concluded that the intensity of grazing was concentrated on 400-500 meters from water points which can be considered as critical zone.

Mountainous rangelands ecosystems provide best natural habitats, biodiversity, soil and water conservation; thus their sustainable management need information and knowledge about relationship between elements of this ecosystems. This study designed to investigate the relationship among ''A. parrowianus" with soil factors as pH, N, P, K, EC, texture and topographical elements such as aspects, slope and elevation classes in mountainous rangelands of central Zagros. For this purpose, the study area divided into three elevation classes and three classes of slope and defined four aspects in it. Flora and vegetation types were studied by physiognomic- floristic method in the field. The factors of vegetation (canopy cover and density of A. parrowianus) were measured on transects using systematic-randomized method. We sampled soil in each area and assessed above factors. To compare mean of vegetation and density of A. parrowianus between elevation and slope classes and different aspects and interactions, multi-way analysis of variance and to compare means of interior classes of factors and existence significant difference among them one-way analysis of variance and homogeneity Duncan test with software SPSS was used. Results showed that topographic factors and their interaction effects and soil characteristics in different aspects had significant effect on cover percentage and density of A. parrowianus. The maximum of canopy cover percentage of ''A. parrowianus" related to eastern aspect (sandy-loam) and slope class of 30%-50% and maximum of density related to northern aspect (clay texture) and slope class of 20%-30% and both of them related to elevation class of 2300-2500m. The minimum of canopy cover percentage and density of A. parrowianus respectively related to western and southern aspect (both have sandy-loam texture), slope class of 50%-60% and elevation class of 2500 < m. Changes of canopy cover has relation to EC, OC, N and K. Changes of density has relation to litter, stone, pH, P, K and OC.

Bagheshad region a part of Khojair national park with 2310 hectares area, is located in 22 Km far from east of Tehran in south of Haraz road. Vegetation of this area was studied based on Braun-Blanquet method. Phytosociological data was analyzed by AFC and CAR methods using Anaphyto software. In this area 9 plant associations and 6 plant sub-associations have been distinguished. Ecological characteristics showed that distribution of plant associations is dependent on altitude, slope, soil depth and texture. Other ecological factors such as pH, calcareous, N, P, K and organic matter contents have less importance in distribution and habitat of plant associations.

Vegetation and soil dynamic study on grazed and ungrazed rangelands is significant for improvement range management. For this reason, the effect of 26 years of grazing protection were studied on vegetation and soil infiltration dynamic on two range condition sites (enclosure and exclosure) in Isfahan, province. Random sampling was done in two range sites using 50 (2x 1m2) quadrates along five 100mlong transect and the vegetation parameter and soil infiltration was studied simultaneously in both excluded and exposed range sites. In this study vegetation characteristics as well as vegetation floristic, canopy cover, plant density, plant composition, plant diversity and soil infiltration were recorded during grazing season from 2006 to 2007. The results indicated that vegetation characteristics had significant differences between excluded and exposed range sites (P<0.05). The analysis showed that canopy percentage and density in the enclosure and exposed sites had significant difference and their amount increased significantly in enclosure range site (P<0.01). The vegetation cover in encluded site was mainly comprised of I and II class plants while III class plant mainly occupied the exposed site. Whereas the diversity of the two areas had no significant difference (P<0.45). This research indicated significant increase in gramineae in the enclosure site compared to surrounding exposed site, but forbs species had considerable decrease (P<0.5). Also this research showed significant decrease in soil infiltration in the exposed (Grazed) range site compared to enclosure range site (P<0.05). Litter was higher inside and bare soil outside the enclosure (P<0.05).The results of the experiment showed that infiltration rate reduced from enclosure area to exclosure area as well as through grazing season. Comparing vegetation and soil infiltration on enclosure show that vegetation condition and soil infiltration were good, and enclosure cause improve range condition in this region.

This study was conducted to determine seed germination rate of Agropyron desertorum and A. cristatum from four sites .In this study we have used factorial design based on complete randomized design with seven salinity treatments of 0, 75, 150,225, 300, 375 and 450 Mm NaCl. Seeds were incubated at 4°C for a few days and then surface-sterilized with 5% (v/v) sodium hypochlorite. The experiment was carried out under 70% relative humidity at 25°C with a photoperiod of 8:16 h light/dark. Germination percentage and seed germination rate were measured, and the data were analyzed by one- way ANOVA and Duncans multiple comparison test. No significant differences were observed between A. desertorum and A. cristatum with respect to seed germination rate. The interaction effect between species and salinity on germination was neither significant. The effect of various salinity levels on seed germination was significant at 1%. Seed germination was stopped at 300mM NaCl. Salinity levels at 0, 75, 150 and 225 mM had significantly different effects on seed germination. Overall, seed germination rate and percent of germination decreased with increasing salinity concentration.

Soil seed bank is an important part of plant diversity but little is known about its structure and dynamics. Soil seed bank size and composition like standing vegetation cab be influenced by environmental factors and management. Knowledge of soil seed bank and its changes can be important for conservation, restoration, and management of rangelands. In this study species composition in both vegetation and soil seed bank were identified for two rangelands (scrubland and shrubland) in Firoz Abad in Fars province. Soil seed bank size and composition was determined by soil sampling and seed germination in glasshouse. Results of this study showed that a total of 76 species were in both vegetation and soil seed bank but most of them were either unique to the seed bank or vegetation. We found only five species common in both. Species richness in standing vegetation was more than that in soil seed bank. Greater number of seeds germinated from upper layer of soil (5 cm). There was no similarity between vegetation and soil seed bank in both vegetation types, thus management needs to take in account both source of species.

Determination of range suitability is one of the most important factors in rangeland management. In the present study therefore, suitability of Lasem of Haraz rangelands in Pankouh, Mianroud, Gatechal & Sorkh pileh sub-basin of central Alborz mountains in Mazandaran province were examined by using three factors including forage production, water resources and soil erodibility. The PSIAC method was used to determine soil erodibility. Water resources suitability was evaluated by investigation of the factors quality, quantity and distance from water resources. The range suitability for sheep grazing also determined following evaluation of production of each plant type, range land situation, palatability and allowable use factor. The range suitability was finally determined by integrating of three factors forage production, water resources and soil erodibility, using Geographic Information System (GIS) and the, method discussed by FAO. The results attained from the study indicate that the slope factor was most effective factor in declining range suitability. It was also observed that 3.7 % of rangeland were grouped at S1 CLASS (good), 22.7% were grouped at S2 class (medium), 41.8 % at S3 class (low) and finally 31.8 % at N class (non - suitable ). It was further concluded that the class N was located within the slope classes of more than 60 %. The maximum surface area however, was related to S3 class suitability.

Erosion, as a natural phenomenon, can create many problems, if it increases more than threshold. Many soils areas have been lost by erosion every year. It is extensive in improving countries because of the population rate's increasing and expression destruction of natural resources. Haraz Road, as a connective distance of Tehran-north of Iran, has almost some erosion problem, particularly landslide. Land use is one of the main reasons of landslide in this area. Influence of each land use has been investigated by GIS at this research. The results have been showed that landslide has mostly occurred around of residential and garden-agricultural areas. And it has also considerably decreased in rangeland.

Providing accurate data on soil erosion and sediment yield is a vital task for soil and water conservation in the watersheds. Towards this attempt, application of erosion and sediment yield models is an efficient tool. In the present study, it was aimed to evaluate the applicability of HEM (Hillslope Erosion Model) in prediction of storm-wise sediment yield in rangeland areas, Markazi province, using soil erosion standard plots and recording 11 observed storm events. In order to run the model, all input data viz. runoff depth, vegetation cover density, land surface cover, soil texture, slope steepness and length were determined. The results of the study verified the low capability of the un-calibrated HEM model in simulating the observed values. The performance of the model was then increased after subjecting it into calibration of default value of erodibility parameter to 1.1. The difference of estimated and observed values was therefore found statistically non-significant with determination coefficient and estimation error of 0.83 and 54.9%, respectively.