Investigation of Relation Vegetation and Some Soil Physico-Chemical Characteristics in Three Rangeland Habitats

摘要

Knowledge of the effect of ecological factors on establishment of vegetation distribution is crucial in the management of rangeland ecosystem. The aim of this study is to investigate relation between soil factors and plant species to determine the most effective factors between in three rangeland habitats; grassland, grassland-shrubland and shrubland in the Khanghah watershed of Urmia (Iran). The present species were recorded in each habitat using a randomized-systematic sampling method. In each habitat canopy cover and density of plant species were estimated within 30 quadrates of 1 m~(2) of located along 3 transect of 100 m. The soil samples were taken from the depth of 0 - 15 and 15 - 30 cm of the soil within 30 quadrates. Soil properties organic carbon, particulate organic matter-carbon, soil organic matter, clay, silt, sand, pH, EC, bulk density, phosphorus, potassium and CaCO3 were measured. Relationships between soil factors and vegetation were determined using Multivariate techniques including Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA). The results of the CCA showed that among soil factors, EC and Organic Matter are the most effective for describing the distribution of vegetation in three rangeland sites. In grassland habitat with reduction of nutrients, at first, grasses will replace the forbs and in the next stage, the grasses are replaced by shrubs. This trend is accompanied by decrease of organic matter, organic carbon, clay and silt. Ultimately the pH, EC, potassium, and CaCO_(3) rate will increase in the shrub land.