عنوان مقاله [English]
Agrobiodiversity has been operated as a foundation for sustaining food production systems and ecosystem services function in human societies. Biodiversity is known as a source for the environmental process and ecosystem services. Ecologists believe that increasing the species richness in farms is the cause of ecological stability in crops. Many studies have been done in relation with the importance of crop diversity. Most of them stated that crop diversity is one the main key to form ecosystem services in ecological ecosystem. Economically, polyculture can reduce production risk. Furthermore, crop diversity can lead to increase productivity by several procedures such as pest control and soil fertility. Eventually, crop diversity brings economic stability. The purpose of this study, was to calculate crop diversity using the biodiversity indices in Kermanshah province.
Materials and Methods
Kermanshah province is located in west of Iran with latitude of 33 to 35 and longitude of 45 to 47 and covers 2.5 million hectares. Crop data includes planting area in 13 cities during 1999 and 2010. Thirteen cities in the area were evaluated in the study, including Eslamabad, Paweh, Jawanroud, Dalahu, Ravansar, Sarpol-e Zahab, Sonqor, Sahneh, Qasr-e Shirin, Kermanshah, Kangawar, Gilan-e Gharb, Harsin. Crop data was obtained from ministry of agriculture. In order to quantify crop diversity, Species richness, Shannon, Simpson, Simpson evenness and Sorenson similarity, indices were calculated. We used the planting area of varoiuse crops to calculate the indices. The Ecological Methodology software was applied to calculate mentioned indices.
Results and Discussion
According to our study, 19 crop species was planted in study area. Wheat was highest planted crop followed by wheat, chickpea, barley and corn so that 51% of planted area was devoted to wheat and 33% was devoted to chickpea. All the 19 crop species was classified into eight families. Leguminos, Poaceae and Solanaceae had highest number of species, respectively. Poaceae (71%) and Leguminos (25%) were highest in terms of planting area. The results of present study demonstrated that 23% of crops type was planted as irrigated and 77% as dry farming. Moreover, 14 species were categorized as summer crops and five species as winter crops. Species richness was 19 across the province. Species richness in Sahneh (19 species), Kermanshah (17 species) and Sarpol Zahab (17 species) were highest. A big difference was obtained between Species richness in irrigated lands (19) and drylands (8), irrigated lands was more that drylands. It may be as result of water availability in irrigated lands. Shannon index was acquired 1.92 in Kermanshah province and highest value was obtained in irrigated land of Pave (2.56) and followed by Sahneh (2.52) and Harsin (2.48). Shannon index in irrigated lands (2.51) was more than drylands (1.48). These findings may attribute to water availability; the crops such as sugar beet (Beta vulgaris L.) , potato (Solanum tuberosum L.) , cucumber (Cucumis sativus L.) , alfalfa (Medicago sativa L.), canola (Brassica napus L.) and paddy would plant if water is available for irrigation. Among the cities, highest Simpson evenness was belonged to dry lands of Ravansar (0.92) and Kermanshah (0.7). It implied that there is no dominant crop in these area or crops are uniformly distributed across the area. However, in other cities wheat (Triticum aestivum L.) is dominated; so, evenness is low. Shannon index was highest for kitchen garden and it was around 2.1 followed by cereals (1.07), forage (0.97), industrial crops (1.33) and beans (0.18). Finally, correlation between Shannon and Simpson indices (0.78**) and species richness and evenness (-0.85**) were calculated.
Wheat and chickpea (Cicer arietinum L.) are the most popular crops and are cultivated in Kermanshah province (west of Iran), however, these plants are dominance than others. Cultivate monoculture systems in the province has increased the vulnerability of agricultural systems and for the low diversity, the risk of pests, diseases, and weeds are high than diverse systems.