Assessing Impact of Anthropogenic Disturbances on Forage Production in Arid and Semiarid Rangelands

Forage is one of the main products of rangeland ecosystems, which is threatened by different anthropogenic disturbances. This study was conducted to assess the impact of urbanization, rural development, agriculture extension, road construction and industry on forage production in an arid and semiarid rangeland using InVEST habitat quality model in spring 2018. In 14 rangeland types, thirty 2×1m quadrats were randomly located to measure forage production using double sampling method. Habitat quality was mapped based on the relative impact of each threat, the relative sensitivity of each rangeland type to each threat and the distance between the habitats and threats. The results showed that there is a significant relationship between rangeland condition and habitat quality (p<0.01). Habitat quality varied between 0 and 0.77 across the study region. Habitats with low quality comprised half of the total area (51%) where anthropogenic factors were concentrated. Habitat quality was significantly correlated with forage production (p<0.01). The dominant species Artemisia sieberi was replaced by invasive species Salsola brachiata and forage production was decreased to the minimum 21 kg ha-1 in habitats with low quality. Rangelands with medium habitat quality produced two and a half times more forage than the ones with low habitat quality and half of the ones with high habitat quality. Astragalus gossypinus and Artemisia aucheri in high habitat quality areas supplied the highest forage production (216 kg ha-1). Since the large areas of agricultural lands are in the low quality habitats, agriculture can be considered as the main threat of forage production. Hence, the extension of agricultural lands with short-term benefits should be controlled in order to improve ecosystem services which have long-term benefits in sustainable development.