جستجوی مقالات مرتبط با کلیدواژه "litter" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

This study was conducted to evaluate the effect of polymer mulches and plant mulch on some soil physical properties. For this purpose, effects of synthetic polymer, natural polymer, natural - synthetic polymer, and litter, On some physical properties of soil at two depths (0-5 cm and 5-30 cm) and two time periods in a completely randomized design with four replications was studied. 10*10 meter experimental plots were considered and mulches covered 2 cm of the soil surface in each plot. The results showed that the use of mulches in the first week of applying, affected the bulk density (3.6% increase in synthetic polymer), porosity (6.01% increase in synthetic polymer), temperature (2.52% increase in litter and 1.85 decrease in natural polymer) and humidity (16.67% increase in synthetic polymer) at the layer of 0-5 cm, Soil moisture (16.67% increase in synthetic polymer) was also affected at the depth of 5-30 cm. Six months after the experiment began, mulches were applied, made a significant difference compared to control in the bulk density (4.81% and 2.12% decrease in synthetic polymer for 1st and 2nd layers respectively), porosity (8.23% increase in synthetic polymer for 1st layer and 4.12% increase in natural - synthetic polymer for 2nd layer) and moisture content of both surface and beneath soil (103.53% and 48.6% increase in natural - synthetic polymer for 1st and 2nd layers respectively), also the electrical conductivity of the first depth of soil (6.23% decrease in natural - synthetic polymer) was affected.

Fire is one of the most important influencing factors on the structure and composition of plant communities, especially in arid and semiarid rangelands. This study was designed to investigate the role of fire on vegetation dynamics in semi-steppe rangelands of Central Zagros. A stratified random sampling was used to collect the data from six sites with one and five years after the last fire. At each rangeland site, 20 plots with four square area meters, 10 plots in the burned sites and 10 plots in the control sites, were used. The cover percentage of each species was accurately recorded. A one-way analysis of variance and Tukey's test were used to compare each of the variables. The results showed that the fire significantly reduced the vegetation cover and litter, and increased the bare soil surface in the region. The composition of the fire region was close to the control area after a period of five years. The fire caused a decrease in the percentage of shrubs and an increase in the proportion of perennial grasses, annual grasses, and annual forbs in the region. The fire also changed the vegetation composition of rangelands, so that the proportion of hemicryptophytes, therophytes, and geophytes were decreased while chamaephytes increased. Fire also increased the proportion of high and moderate palatable species (class I and II) and reduced the proportion of class III species. Based on the results of this study, it can be concluded that the fire reduces litter and increases the bare soil; consequently, the soil erosion is exacerbated, hence this should be considered in rangeland management. Overall, uncontrolled fires in the semi-arid regions of the country will not lead to the restoration of vegetation cover.