Vegetation community in relation to the soil characteristics of Rineh rangeland, Iran

The aim of this study was to investigate relationships between soil properties and plant species to determine the most effective factors separating vegetation communities in Rineh rangeland. Three stratifying variables were selected including slop, aspect and elevation. The study area was partitioned by combining these classes to generate homogenous units. 1m2 quadrates were located at sampling sites in each homogenous unit randomly. Vegetation cover data were recorded using ordinal scale of Daubenmire cover-abundance scores in each quadrate. Soil samples were collected based on area from 0-15, 15-30 cm depths in each sampling site. Total nitrogen, organic matter, pH, total phosphorus, water retention capacity, permanent wilting point, available water capacity, potassium, water holding capacity, CaCO3, saturation moisture, bulk density, real unit weight and percentage of fine earth fragments (sand, silt and clay) were measured. Both classification and ordination techniques were employed including TWINSPAN classification, DCA and CCA. The TWINSPAN classification of the sample sites have resulted in ten groups. According to the results of DCA, length of gradient represented by axis 1 was >5 SD, indicating that CCA was the appropriate ordination method. CCA axis 1 was correlated to phosphorus (-0.460) in the first layer and phosphorus (-0.493), sand (0.533) in the second layer while the CCA axis 2 was correlated to phosphorus (0.394), sand (0.533) in the second layer. The species-environment correlations are higher for the first three canonical axes, explaining 18% of the cumulative variances

Accumulation and distribution of metals in Phragmites australis (common reed) and Scirpus maritimus (alkali bulrush) in contaminated soils of Lia industrial area

The concentration of three metals, zinc, copper and chromium in roots, rhizomes, stems and leaves of Phragmites australis (common reed) and Scirpus maritimus, and in the corresponding sediment and water samples from Lia industrial area (Qazvin, Iran) were investigated to determine difference in distribution among plant organs. Data were collected at during 1-year period. Results showed that metals concentrations in plant organs decreased in the order of roots ¿ rhizomes ¿ leaves ¿stems. Concentration of Zn, Cu and Cr were enriched in roots and rhizomes of both plants in summer and autumn. Stem concentrations of metals in S. maritimus however, had no significant difference throughout 1-year period. In contrast, the metal contents of leaves were elevated in spring and autumn. Patterns of leaves and stem concentration of Zn, Cu and Cr were similar to S. maritimus leaves.This research was supported by a grant from the Natural Resources Faculty of Tehran University.Peer Reviewe

Plant Richness and Diversity Response to Different Treatments of Animal in Kalashak Rangelands (Case Study: Kermanshah Province)

Evaluation of plant richness and diversity is important in rangeland ecosystems because biological control, conservation of genetic resources and the control of natural ecosystems are possible by identifying diversity. One of the factors affecting the richness and diversity is animals' utilization of the vegetation. Therefore, this research was done to study the plant richness and diversity response to different treatments of animals. To this end, four sites with none, half, equal and twice as much grazing capacity were selected. Treatments were identified due to vegetation cover changes, distance from water, distance from the village and grazing times. Using located transects, samples were (systematic randomization) taken from vegetation (transects four and plots 40 and in the area a total of 160 plots were harvested). The results showed that the highest species richness and diversity belonged to sites' grazing capacity equal and grazing capacity half. But this was the least in the without-grazing site. Thus, animals' exploiting the rangelands properly (grazing capacity equal and grazing capacity half) can increase the richness and diversity. Lack of rangeland long-term grazing leads to poor plants. So, both severe grazing and long-term exclusion should be avoided. The full protection of rangeland does not necessarily lead to the maximum diversity

Modeling hydrological impacts of afforestation on intermittent streams

Although the majority of river networks across the world are intermittent or ephemeral, afforestation management of these catchments is mostly founded on studies in perennial catchments. The hydrological model CATHY (CATchment HYdrology) was used here to simulate the effects that different degrees of progressive conversion from pasture to plantation have on the streamflow generation in intermittent streams. The model was applied to two rural catchments with different size and topographic features in southwest Victoria, Australia. Simulated scenarios included different levels of plantation establishment in pasture areas planting gradually from downslope to upslope and vice versa. Different models for root water uptake were compared to account for water stress, oxygen stress, and root water compensation. A function of root growth over time was also explored to see how it affected model results. The model results show that complex interactions between topographic features and afforestation patterns are crucial in controlling catchments hydrological behavior. In particular, results show that planting in the prone-saturation areas has the largest effects on streamflow. Oxygen stress has a more significant impact than root water compensation on streamflow changes. A time dependent root growth results in smaller streamflow reduction on average, although with different impacts on the two catchments, also due to the interplay between topography and plantation patterns. Overall, our results show that there are multiple factors affecting the water balance when a catchment is partially or completely afforested and those must be taken into account when implementing forestry management strategies