No Negative effects Positive effects
1 Reduce crop yield , Reduce crop quality Prevent erosion
2 Serve as an alternative hosts of pests: insects, diseases, birds and rodents. Provide habitat and food for predatory and parasitic insects.
3 Interfere with crop management and harvest. Sources of genes for crop breeding.
4 Impair human and livestock health. Sources of medicines and other useful substances, human foods and animal fodders.
5 Depreciate land value. Add organic matter to the soil.
6 Compete with crops for insect Pollinators. Provide aesthetic pleasure and useful for landscape.