冀北退化草原生态修复研究

Study on ecological restoration of degraded grassland in Northern Hebei

为修复冀北退化草原生态,该试验在丰宁县外沟门草原设置了5个施氮水平(0、60、120、180、240kg/hm^(2)),以紫花苜蓿、苇状羊茅单播和混播(1:2、1:1、2:1)改良草地。研究了在不同施氮水平下,单播和混播对牧草产量的影响及混播物种的竞争关系,为建植高产、稳定、可持续的混播草地提供理论基础。结果显示:施氮水平和混播方式显著影响牧草产量。混播相较于单播,具有较大产量优势。混播比例对种间竞争关系有直接影响。施氮量从60kg/hm^(2)增加到120kg/hm^(2)时,产量和增产率急剧增加,随着施氮量的进一步提高,产量和增产率增长变缓。施氮量为240kg/hm^(2)时,不同播种方式牧草产量均达到最大。紫花苜蓿对氮肥的响应弱于苇状羊茅,紫花苜蓿对于苇状羊茅具有更强的竞争优势。混播草地中苇状羊茅比例越低,种间竞争作用就越强烈,减少竞争力较强的紫花苜蓿比例,有助于种间关系共存稳定。因此,在丰宁半干旱草原地区,建植第1年施氮量为120kg/hm^(2),紫花苜蓿、苇状羊茅1:2混播时,可以实现最优产量。

In order to restore the degraded grassland ecology in northern Hebei,five nitrogen levels were set in the Waigoumen grassland of Fengning County,which are 0,60,120,180,240 kg·hm-2,monoculture and mixed sowing(1:2,1:1,2:1)were used to improve Medicage sativa L.and Festuca arundinacea grassland,and the effects of monoculture and mixed sowing on forage yield and the competition relationship between mixed sowing species were studied under different nitrogen levels,and provides a theoretical basis for stable and sustainable mixed grassland.The results showed that nitrogen levels and mixed sowing methods significantly affected forage yield.Compared with monoculture,mixed sowing has a greater yield advantage.The mixing ratio has a direct impact on the interspecific competition.When the nitrogen rate increased from 60 kg·hm^(-2) to 120 kg·hm^(-2),the yield and yield increase rate increased sharply,and with the further increase of nitrogen rate,the yield and yield increase rate increased slowly.When the nitrogen rate was 240 kg·hm^(-2),the forage yield of different sowing methods reached the maximum.The response of Medicage sativa L.to nitrogen was weaker than that of Festuca arundinacea,and Medicage sativa L.has a stronger competitive advantage for Festuca arundinacea.The lower the proportion of Festuca arundinacea in the mixed grassland,the stronger the interspecific competition.Reducing the proportion of more competitive Medicage sativa L.is conducive to the coexistence and stability of interspecific relationships.Therefore,in the semi-arid grassland area of Fengning,the optimal yield can be achieved when the nitrogen rate is 120 kg·hm^(-2) in the first year of planting,and Medicage sativa L.and Festuca arundinacea are mixed at 1:2.