Effect of mowing and water and nutrient additions on the compensatory responses of Heteropogon contortus

The compensatory growth characteristics of Heteropogon contortus, a common native herb and test material in the dry, hot valley of the Jinsha River, with the addition of water and nutrients and mowing was studied. The dry matter weight of litter decreased after mowing; however, it increased with high-frequency precipitation or when nutrients were added. When nutrients were added, the dry matter weight of crown was higher after the high frequency precipitation treatment. The highest dry matter weight per plant and the weight of its roots, stems, and leaves appeared when there was high frequency precipitation, added nutrients, and when unmowed. The root-shoot ratio of plants with no added nutrients but had mowed crowns was significantly higher when compared to that of the other plants (P < 0.05) regardless of the frequency of precipitation. The reproduction allocations of plants with no added nutrients, mowed crowns, and high and low precipitation frequency (1.2%, 0, respectively) were significantly different (P < 0.05) and lower when compared to that of the other plants. The compensation indices for the biomass of the plants and the roots, stems, leaves, inflorescences, and fruits after mowing were the highest when precipitation frequency was low and when nutrients were added. Furthermore, the growth patterns of the plants and their roots, stems, leaves, inflorescences, and fruits were undercompensated. Therefore, mowing had an adverse effect on the formation process of litter and the accumulation of biomass in the H. contortus meadow; however, the appropriate amount of water and fertilizer can help alleviate this unfavorable effect, although, the under-compensatory growth pattern of the plants cannot be changed.