Establishing soil quality index (SQI) is a common procedure in assessing soil capacity function. Various SQIs can be designed and used in soil evaluations upon the aspects including data set, efficiency, and sensitivity. This study was conducted to distinguish a representative soil minimum dataset (MDS) among 16 total dataset (TDS) properties in semi-arid rangeland ecosystems of northwest Iran. Appropriate SQIs were calculated applying the models of integrated quality index (IQI) and Nemoro quality index (NQI). IQI by simple additive and weighted additive approaches and also NQI were calculated for both MDS and TDS based on linear transformation of soil parameters. Totally, different SQIs including simple additive IQI, weighted additive IQI, and NQI were separately established to TDS and MDS. Sensitivity index (SI) and efficiency ratio (ER) of each SQI were then calculated for prioritizing and selecting suitable index. Principal component analysis (PCA) revealed that seven indicators are appropriate MDS for accounting 70.27% of data variations. Maximum and minimum SI belonged to MDS-NQI and TDS-weighted additive IQI, with values of 2.597 and 2.056, respectively. MDS-NQI has the highest value of ER (85.71), while TDS (both weighted and simple additive)-IQI has received the lowest value of ER (71.43). Final prioritizing according to ranks of SI and ER showed that MDS-NQI is the most suitable approach in soil quality assessment of semi-arid rangelands. Therefore, it could reduce cost due to measuring fewer indicators in the laboratory on contrary premise to have more dense soil samples in the field.
Abstract. Hasanpori R, Sepehry A, Barani H. 2019. Rangeland conversion to dryland and its effects on species diversity and richness. Biodiversitas 20: 2043-2047. Species diversity and richness status in ecosystem is important in confront to environmental threats and is guidance in plant management. Due to increasing land use changes and destruction of rangelands in western Iran, this research was conducted to study the effects of land use change from rangeland to dryland on species diversity and richness of vegetation cover in three land uses of rangeland, dryland and abandoned dryland. Vegetation cover data were collected from established plots in each land use. Species diversity and richness were calculated in each land use by Simpson and Shannon indices and Menhinick and Margalef ones, respectively. Results showed that these indices are significantly different at 95% level in three land uses. The highest species diversity and richness indices were in rangeland and the least were in dryland. So, we found that four above measured indices, are illustrative and accurate enough to demonstrate differences between several land-use diversity and richness. Simplification on a dynamic and diverse ecosystem, and land conversion to dryland reduced plant species numbers in the new ecosystem, and simplify species composition, so simple dryland ecosystem would be fragile against environmental threats. Therefore to reduce unfavorable effects of land use changing, paying more attention to species diversity conservation must be a base to management decisions.
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