对黑麦草(Lolium perenne)与白三叶(Trifolium repens)、鸭茅(Dactylis glomerata)、白茅(Imperata cylindrical)、芒(Miscanthus sinensis)、绣线菊(Spiraea japonica var. nepalensis)和地榆(Sanguisorba officinalis)等6种植物之间在不同压力和干扰条件下的竞争关系进行了试验研究，以便进一步探讨黑麦草草地群落退化演替的机理，为今后这种草地的有效管理提供科学依据。试验设置水分条件和土壤肥力两个压力因子处理及刈割频率和刈割强度两个干扰因子处理，其中，水分条件处理包括自然降水（1 800 mm）和自然降水＋浇水（2 300 mm）两个水平；土壤肥力处理包括施肥0 kg·hm-2·a-1、75 kg·hm-2·a-1和150 kg·hm-2·a-1 3个水平；刈割频率处理包括每年刈割1、3、6次3个水平；刈割强度处理包括刈割留茬2 cm和10 cm 两个水平。在专门设计的固定试验装置中，按各种植物单植和分别与黑麦草混植的方法以相同密度种植植物，通过对各处理植物产量的测定，运用de Wit提出的植物相对拥挤系数（RCC），确定在不同压力和干扰条件下黑麦草对其它6种植物的竞争关系。试验表明，黑麦草对白三叶、鸭茅、地榆、白茅、芒、绣线菊的竞争力依次增强。同时，随着刈割次数的增加、水分条件和土壤肥力的提高，黑麦草的竞争力也明显增加，其中刈割次数对黑麦草竞争力变化的影响最大。另一方面，试验还表明，黑麦草等栽培牧草的生长速度和竞争力及耐刈割干扰程度均高于大部分野生杂草植物，但它们忍受环境压力的能力明显低于野生杂草植物，在环境压力大的地区，它们对杂类草的竞争力明显减弱，使得杂类草逐渐占优势。此外，分析表明，对于黑麦草来说，在试验的其它6种植物中绣线菊是压力忍耐（S）型植物；白三叶和鸭茅属于干扰忍耐（D）型植物；其它几种植物对压力和干扰的忍耐性处于中等水平。
The competition relationships among perennial ryegrass (Lolium perenne) and six other species (Trifolium repens, Dactylis glomerata, Imperata cylindrical, Miscanthus sinensis, Spiraea japonica var. nepalensis, and Sanguisorba officinalis) were studied in different conditions of stress and disturbance. The aim was to examine the mechanism of regressive succession of ryegrass community, in order to supply a basis for efficient management of this pasture.Two stress factors (water condition and soil fertility) and two disturbance factors (cutting frequency and cutting intensity) were included in the experiment. The water condition treatment included two levels, which were natural precipitation (about 1 800 mm) and precipitation + watering (about 2 300 mm). The soil fertility treatment included three levels at which fertilizer was applied: 0 kg·hm-2·a-1, 75 kg·hm-2·a-1 and 150 kg·hm-2·a-1. The cutting frequency treatment included three levels at which plants were cut: 1, 3 and 6 times per year. The cutting intensity treatment included two levels of stubble height, 2 cm and 3 cm. The plants were planted with the same density in monoculture and in mixture with ryegrass in a fixed device. After yields of plants in different treatments were measured, the plant relative crowding coefficient (RCC), which was quantified by de Wit, was estimated. Finally the competition relationships among ryegrass and six other species under different stress and disturbance conditions were determined. The experimental results showed that the competitive abilities of ryegrass were ordinal superior to T. repens, D. glomerata, S. officinalis, I. cylindrical, M. sinensis and S. japonica var. nepalensis. Moreover, the competitive ability of ryegrass increased when cutting frequency, moisture and soil fertility increased. Cutting frequency was the most important factor to affect competitive ability of ryegrass among the 4 factors studied. On the other hand, the experiment indicated that the growth rate, competitive ability and cutting disturbance tolerance of cultivated herbage (ryegrass, T. repens and D．glomerata) were higher than that of wild species. However, the stress resistance of cultivated plants was lower than that of wild species. When environmental stress increased, cultivated plant’s competitive ability relative to wild species would weaken, and wild species would predominate in the pasture. Meanwhile, the experiment implied that for ryegrass, S. japonica var. nepalensis was a plant of stress tolerance (S) in 6 studied species, T．repens and D．glomerata belonged to plants of disturbance tolerance (D), and the other species were intermediate in stress and disturbance tolerance.
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