Effects of fertilizers on plant diversity, density, and uniformity in Golestan rangelands

ABSTRACT

One of the management operations in rangeland ecosystems for pastures restoration and improvement is fertilizer application. This study was designed to investigate the effect of fertilizer (50 kg/ha urea and ammonium phosphate fertilizers) on species diversity changes in a 100-ha experimental field of Salmechal Rangeland, Golestan Province. Plant species mean canopy cover was recorded using a 50-m² sampling plot. Statistical analysis was performed using Excel 2007 and PAST software. Fertilizer application increased the number of species present in the region from 21 to 51 and the plant families from 11 to 23. The forbs had the highest proportion (54.91%) and bushes and shrubs had the lowest percentage in the region. Fertilizer application increased plant diversity, uniformity, and coverage of the grasses. There was a significant difference (p < 0.01) between the grass and forbs coverage before and after fertilizer treatments. The results showed that the biological and physiological growth periods of the annual and perennial plants were significantly different before and after fertilizer application (p < 0.01). Also, their proportion in rangeland plant species composition significantly increased after fertilizer application.

KEYWORDS:

• Fertilizer
• diversity
• density
• uniformity