Journal of Arid Biome
Year:2017 | Volume:7 | Issue:1 |Papers Count:8

To investigate relation of slope, aspect and elevation in predicting spatial distribution of tree and shrub species in arid forests of south Yazd, 125 sampling plots were selected in randomized block pattern in five sub-district of study area. In addition to topographic factors, presence of plant species and their frequency were measured and recorded. Logistic regression was conducted and in the case of significance, suitable model was provided. Distribution map of species was drawn according to probabilities derived from logistic regression analysis. To determine accuracy of maps we used 20 percent of primary data. According to these data the rate of accuracy was in range of 90-75 percent. Finally relations between topographic factors and presence of species were interpreted. Results found that elevation is the most important factor for predicting spatial distribution of plant species in study area and predicts from 16 to 46 percents of variations in presence. But slope and aspect were not suitable to be included in the models. According to thresholds determined in the results it can be said that Acer cinerascens and Amygdalus eleagnifolia can be regarded for planting in higher elevations but Amygdalus lycioides is suitable for planting in lower elevations.

Measuring intensity of wind erosion in arid and semi-arid regions is vital for determining the appropriate strategies to control or reduce its effects. There are various methods and models for estimating wind erosion intensity. In this study, potential of an empirical model named, IRIFR (Iran’s Research Institute of Forest and Rangelands), for the estimating of wind erosion intensity in different wind geomorphology landforms in Rafsanjan plain was evaluated by comparing the measured data obtained from the wind erosion meter as a physical – insitu method. Results of both methods showed that 13 and 37% of the study area are classified as high and very high, respectively. Furthemore, wind erosion simulated using the model was highest in sand dune, and orchard landforms had the lowest values. Soil loss in sand dune landform was estimated more than 8000 tons km-2 year-1. Obtained statistical criterion values such as absolute error percentage (AEP=0.37), coefficient of determination (R2=0.85), and particularly the model efficiency factor (MEF=0.97), indicated that despite the differences in measured amounts of soil loss using wind erosion meter and the IRIFR model in some studied geomorphology landforms, the model had a suitable estimation of the wind erosion intensity in the study area. However, the IRIFR model is faced with error in estimating of wind erosion intensity in landforms with high wind erosion risk (class V) and needs to be revised.

Several provinces in Iran are subjected to the invasion of moving sands during permanent and seasonal wind blowing. In this research, effect of oil mulch on biodiversity, richness and evenness indices of soil macrofauna and vegetation has been investigated in Jask region. The research data were including density, canopy and richness of vegetation and the richness and biodiversity of soil macrofauna. Vegetation was sampled using 60 plots with the area of 5x5 m2 and soil macrofuana investigated using 80 pit traps (glasses containing poly ethylene glycol 50%). Richness and biodiversity indices were calculated using Past software. Results of compared biodiversity indices for macrofauna showed that richness of soil macrofauna of mulched areas in autumn and spring, were 2.9 and 16.5 times than the control area, respectively. Shannon’s and Simpson’s biodiversity indices related to autumn were 3.6 and 3.1 times than the control area in mulched areas, respectively. Results of oil mulch effect on richness and biodiversity of vegetation in mulched and control areas indicating similar plant diversity after 10 to 14 years than the mulching process in the studied areas.

Drought is one of the most important environmental stresses that can impair plant growth and crop production. The purpose of Resent paper is to determine the effects of drought stress and Buried by sandon yield, yield components of canola (Brassica napusL.) as well as soil properties. The research was investigated in crop year 2013-14 in the field of Educational Research Institute of University of Zabol. Experiment split-plot in randomized complete block design with three replications. The main plot was drought stress in three levels including; 50, 100 and 150 mm evaporation from evaporation pan and sand buried quantities was considered as the sub – plot in three levels; control, 100 and 200 t/ha. The highest of grain yield (460.87 kg/ha) was obtained from treatment 200 t/hadue to Buried by sand. The result shownthat yield was increased in comparison to the control treatment of about 29.61 percent. The maximum soil temperature shows in treatments of 100mm and 150 mm respectively 27.5co and 28.3co evaporation from pan evaporation and the lowest soil temperatures in 50 mm from pan evaporation treatment was obtained 25.3co.Using sand storm, the soil temperature decreased and the highest soil temperature (28.2co) was observed in control treatment. The interaction of drought stress and sand storm showed that the highest grain yield in drought stress 50 mm evaporation and the application of sand storm 200 t/ha. This was indicates that the positive effect of sand to reduce evaporation.

In This research, considering peripheral circulation approach, drought periods during the 22years (2013-1992) in 21 synoptic stations located in Kerman, Yazd and Isfahan provinces, were calculated using Standardized Precipitation Index (SPI) annually. Tele-connection pattern data extracted from NCEP|NCAR site and were investigated of relationship between major droughts in the region and Tele-connection patterns based on correlation and multivariate regression model. Totally, about 37.42% of the changes Drought Index to SPI in Isfahan and around 51.09 % SPI changes in Kerman and 42.17 % SPI changes in Yazd are exhibited by patterns. Scandinavia Pattern (SCA) in Esfahan and East Atlantic Pattern (EA) in Kerman and Tropical Southern Atlantic (TSA) in Yazd, as the most effective pattern of annual SPI changes, were exhibited in Central Iran.

In order to study the effects of water salinity on fennel seed yield and seed yield components, an experiment was conducted at Agricultural and Natural Resource Research Center of Isfahan in a split plot experiment based on randomized complete block design with three replicates, during 2012- 2014. Four superior Foeniculum vulgare genotypes (Lorestan, Hamedan, P11- 820065 and 11486) in three treatments (control, 5 and 8 ds/m) were investigated. Number of inflorescences and umbels, seeds per umblets, seed yield, weight of 1000 seeds, plants height in 50% flowering and 100% flowering time, dry weight of plant aerial parts, plant dry weight/wet weight, days until 50% flowering and maturing time, percentage of essential oil and essential oil yield were evaluated. Results showed that the effect of salinity was significant on all traits with the exception of essential oil percentage. Effect of genotype wasn’t significant on seed per umblet and seed yield. Interactions of salinity and genotype were significant on all traits except for essential oil percentage. In control treatment P11- 820065 had the highest seed yield and essential oil yield (2359.8 and 91.5 kg/ha, respectively) but by increasing in salinity levels, seed yield of native genotypes was higher than P11- 820065 and Lorestan was the superior genotype with 1463 and 4/38 kg/ha, respectively. There was a positive correlation between seed yield with essential oil and forage yields. Based on the results, salinity stress decreased the seed, essential oil and herbage yield economically.

Increasing of temperature and changing in precipitation patterns, leads to extreme climate events such as drought which drastically impact on agricultural, ecological and socio-economic sectores. Knowledge about the timing, severity and extent of drought can aid planning and decision-making. Drought indices derived from in-situ meteorological data have coarse spatial and temporal resolutions. Thus, obtaining a real-time drought condition over a large area is difficult. Therefore, drought indices which is derived from remote-sensing data, has been widely used for drought monitoring. In this study, two new drought indices, Vegetation Drought Index (VDI) and Temperature Drought Index (TDI) derived from remote sensing data are evaluated based on the Standard Precipitation Index (SPI) derived from in-situ meteorological data. The data included the MODIS sensor images from Terra satellite for the 2001 -2004 and rainfalls data from 50 synoptic stations in Central Iran. Accuracy of the two drought indices based on satellite data carried out using evaluation criteria of R and RMSE in 95% confidence levels compared with drought spatial distribution map of the SPI based on rainfalls monthly data. Results indicate significant correlation between VDI (0.69) and TDI (0.66) indices with SPI index. Thus, the drought indices based on remote sensing data could well use in drought early warning systems.

Flood Spreading on alluvial fans at outlet catchment areas used with the aim of exploiting the floods. It is appropriated method of operation of the seasonal floods of rivers and streams and store them in aquifers. In present research, the impact of flood spreading in recharge aquifer in Herat was studied. For this reason, GRI indicators for piezometers wells (3 wells in the aquifer and around aquifer 6 wells) and SDI index for Qanat downstream (4 Qanats) were calculated. Correlations measured between volume of flood water and Standardized Precipitation Index (SPI) as well as the annual and monthly and were tested with different time delays. The results showed that the correlations between annual GRI index in piezometers with volume of flood and flood volume with long delays at levels 1 and 5% is significant. GRI index monthly in 2 piezometer with flood volumes and in the rest with the Monthly SPI index was significant. The Qanats SDI index with monthly and annual SPI correlates with long delays. Finally, given that 98 percent dewatering occurred in the first three years and for many years has been the area without dewatering, Also, due to reduced permeability and high evaporation, the design of such projects in arid and semiarid areas of low performance is outstanding.