1. Multiple-scale foraging decisions by large herbivores can cause associational effects of focal plant individuals neighbored with different species. Spatial micro-patterns between the focal plant and its neighboring species within patches can affect herbivore foraging selectivity at within- and between-patch scale, which may consequently lead to associational plant effects occurring at both plant individual and population levels. However, these associational effects have not been explored together in the plant-herbivore interaction studies. 2. We aim to evaluate how plant spatial micro-pattern within different quality patches mediate herbivore foraging selectivity, thereby affecting the associational effects of focal plant individuals and population. 3. Using sheep as the model herbivore and a medium preferred species as the focal plant, we conducted a manipulative experiment by allowing sheep grazing freely among three different quality patches, each of which consisted of preferred, un-preferred and focal plant species with different abundances forming spatially aggregated or dispersed micro-patterns. 4. Results showed that, compared with the aggregated plant micro-pattern, dispersed plant micro-patterns within different quality patches increased sheep within-patch selectivity, and caused diverse associational effects of focal plant individuals. Focal plant individuals experienced neighbor contrast defense (i.e. got protection in the high quality patch) and associational defense (i.e. got protection in the low quality patch), respectively, when plants dispersedly distributed in the low and high quality patch. Focal plant individuals simultaneously experienced associational susceptibility (i.e. got damage in the high quality patch) and neighbor contrast susceptibility (i.e. got damage in the low quality patch) when plants dispersedly distributed in the medium quality patch. Furthermore, dispersed plant micro-patterns reduced sheep foraging selectivity between patches, and led to a lower consumption of focal plant population compared with the aggregated plant micro-pattern. 5. Herbivore adopt different within- and between-patch foraging decisions to maintain a high intake of the preferred species in response to various plant micro-patterns, and consequently cause diverse associational effects of both focal plant individuals and population. These associational effects have important implications for understanding the species coexistence and plant community assembly in the grazing ecosystems.