Abstract: Invasive alien species may cause environmental degradation, biodiversity loss, food and water shortage, and high possibility and severity of natural disasters. It is a good way to replace invaded plant by utilizing valuable native species. In this study, same proportion of  native plant Imperatacylindrica and invasive plant Ageratina adenophora was mixed cultured, aimed to understand the competition effect of I. cylindrica to A. adenophora. There was a strong competition between these two plant species. I. cylindrica had a higher competitive ability than A. adenophora, being able to heavily suppress the growth of A. adenophora by shoot competition. Compared with A. adenophora, I. cylindrica could germinate faster, and its plant height and average leaf area were significantly higher. Mixed culturing I. cylindricaand A. adenophora could significantly restrain the growth and tillering of A. adenophora, resulting in the plant height, average leaf area, and chlorophyll content of A. adenophora being 49%, 72%, and 77% of those in monoculture, respectively. On the other hand, mixed culturing had no significant impact on I. cylindrica. In reverse, the tillering of I. cylindrica was promoted, with the tiller number being 132% of that in monoculture. The relative yield (RY) of I. cylindrica was significantly higher than that of A. adenophora, and the relative yield total (RYT) was lower than 1.0. With the prolonged time of mixed culturing, the relationships mentioned above became more obvious, suggesting that it would be a promising strategy to replace A. adenophora by I. cylindrica.

Key words: Great bustard, Behavior, Time budget, Daily rhythm, Activity