不同混播方式下豆禾混播草地群落稳定性的测度与比较

以红豆草、紫花苜蓿、红三叶、鸭茅、无芒雀麦和猫尾草6种豆禾牧草在混播种类为3、4、5、6与豆禾比5∶5、4∶6和3∶7条件下建立混播草地。依据2008-2012年各混播组合的群落组分稳定性、功能稳定性和可入侵性，比较了21个豆禾混播组合的群落稳定性。从组分稳定性来看，含红豆草的组合豆科植物稳定性较差;而不含红豆草组合豆科植物稳定性较高;从功能稳定性来看，随着混播种类数量的增加，群落稳定性呈增加趋势，豆禾比4∶6的群落稳定性低于豆禾比5∶5和3∶7。从可入侵性来看，混播种类对其影响较小，豆禾比5∶5具有较高的稳定性。通过模糊综合评价，包含组分稳定性、功能稳定性和可入侵性3个方面的群落稳定性以豆禾比为4∶6较低，而混播种类对群落稳定性影响较小。因此，混播种类与比例仅能影响到群落稳定性的某一方面，还需探寻适宜的时空尺度与评价“标尺”下影响群落稳定性的其他因素。

Determination and comparison of community stability in different legume-grass mixes

The community stability of different legume-grass mixes has been analysed using the fuzzy synthetic evaluation method. Onobrychis viciaefolia, Medicago sativa, Trifolium pratense, Dactylis glomerata, Bromus inermis and Phleum pratense were used in four different combinations (3, 4, 5 or 6 species in each mixture) at three sowing ratios of legume to grass (5∶5, 4∶6 and 3∶7). In order to measure community stability and susceptibility to invasion, seven indexes (including the relative densities of grasses and legumes, the yields of forage, crude protein, ether extract, neutral detergent fiber, and the relative total yield) were analysed from 2008 to 2012. The component stability of legumes in mixtures with O. viciaefolia was lower than that of grass, while it was higher in mixtures that did not contain O. viciaefolia. Community stability increased with increases in species diversity. Stability was lower in the 4∶6 legume-grass mix than at other ratios. Susceptibility to invasion was higher at 5∶5 than at other ratios and was minimally affected by species diversity in the various mixes. Fuzzy synthetic evaluation showed that stability at 4∶6 was lower than at other ratios and that stability was rarely affected by species diversity. In conclusion, the study suggests that species diversity and the ratio of legumes to grass may affect some rather than all aspects of community stability. Further research is needed at appropriate time and space scales and using standardized indices to discover what other factors are influencing the stability of legume-grass mixes.