Vegetation Cover Dynamics in Semi-Steppe Rangelands of Ardabil Province, Iran

Abstract

Rangeland vegetation dynamics can be affected by various natural and unnatural factors over time. The purpose of this study was to investigate the dynamics of vegetation under the climatic conditions and soil properties. Accordingly, data collection for evaluating vegetation dynamics in rangeland ecosystems of Ardabil province was conducted at three research sites including Moqan winter rangeland, and Nour and Aqdagh Khalkhal summer rangelands in 2009 followed for four years. Vegetation variables were measured using transects and sampling plots. Meanwhile, at the location of each plot, soil moisture was measured at two or three depths of 0-15, 15-30 and 30-45 cm using a Time-Domain Reflectometer (TDR). According to the results, in the Nour site, the changes recorded for shrubs such as <em>Onobrychis cornuta</em> L. and forbs were significant (P<0.01). However, the changes recorded for the perennial grasses including <em>Alopecurus aucheri</em> L., <em>Bromus tomentellus</em> Boiss. <em>Festuca ovina</em> and <em>Koeleria caucasica</em> Trin. Ex Domin were not significant. In the Aqdagh site, the changes of perennial grasses including <em>Agropyron cristatum</em>, <em>Bromus tomentellus</em>, <em>Festuca ovina</em> L. and <em>Koeleria caucasica</em> as well as forbs were significant (P<0.05). The changes of annuals were found significant (P<0.01). No significant differences were recorded for the shrubs such as <em>Onobrychis cornuta</em> and <em>Thymus kotschyanus</em>. In the Moqan site, the changes of dominant shrub (<em>Artemisia fragrans</em>) and annuals were significant (P<0.01). Soil moistures during the growing season and over the years were varied; however, the trend of changes in soil organic carbon was slow. Accordingly, the results of this monitoring process from year to year changes in the main species of vegetation, soil, and soil erosion can be useful as a guide to correct the current methods used for the management of rangelands.