Diversity of weeds species in citrus farms of Taymma (Tabuk, Saudi Arabia): implication for invasive species ecology.
Invasive species of weeds in agroecosystem is known as a critical problem which is associated with severe economic loss as they compete the crops for niche, water and nutrients. There is a lacking in the information about biology and ecology of weeds communities in agroecosystems of Saudi Arabia particularly citrus farms. The present study aimed to investigate the distribution and diversity of weeds in selected citrus farms of Taymma (Saudi Arabia). A total of 36 weed species belonging to 20 families were recorded in citrus farms of Taymma. The species Aizoon canariense, Artemisia seiberi, Morettia parviflora, Oxalis corniculata, Setaria viridis and Salsola imbricata were the dominant species in the citrus farms. The dominant family was Poacea, Asteraceae, Brassicaceae and Chenopodiaceae. The total number of weed species (gamma diversity index γ), ranged between 25 and 27. Three diversity indices were calculated; Shannon-Weiner (H′), Simpson (1-D) and Margalef. There was no significance differences in the three diversity measures among the selected citrus farms (One-way ANOVA Shannon-Weiner (H′); F2,12=0.025 and P=0.975, Simpson; F2,12=0.071 and P=0.932, Margalef; F2,12=0.113 and P=0.895). The variance in the species among the sites as expressed by beta diversity (β) varied slightly among the studied farms. The present study provides essential information about ecology of weeds in citrus agroecosystem. It is recommended that further ecological studies should be carried out to better understand the biological and environmental factors that structuring the weeds communities in arid region.