基于生态位理论的豆禾混播草地群落稳定性利用管理研究

Study on the Stability Utilization and Management of Legume-Grass Mixtures Community Based on Niche Theory

为探明刈割与施肥影响河西地区豆禾混播草地稳定性的生态学机理,本研究以‘清水’紫花苜蓿(Medicago sativa)、无芒雀麦(Bromus inermis)和长穗偃麦草(Elytrigia elongata)建植的混播草地为对象,设置3个留茬高度(5 cm(A_(1)),8 cm(A_(2))和11 cm(A_(3)))和6个施肥处理(CK(B_(1)),150 kg P_(2)O_(5)·hm^(-2)(B_(2)),75 kg N·hm^(-2)+225 kg P_(2)O_(5)·hm^(-2)(B_(3)),150 kg N·hm^(-2)+150 kg P_(2)O_(5)·hm^(-2)(B_(4)),150 kg N·hm^(-2)(B_(5)),225 kg N·hm^(-2)+75 kg P_(2)O_(5)·hm^(-2)(B_(6))),并对各草种的生态位特征进行了分析。结果表明:相较于留茬高度,牧草重要值对施肥的响应更敏感,然而提高留茬可增加无芒雀麦重要值并控制过高的紫花苜蓿重要值,其中A_(2)B_(3)处理效果最好;A_(1)可增大各牧草生态位宽度,且均在第3茬的A_(1)B_(4)处理最大;紫花苜蓿与无芒雀麦、紫花苜蓿与长穗偃麦草、无芒雀麦与长穗偃麦草间的生态位重叠分别在第2茬的A_(2)B_(6),A_(2)B_(1)和A_(2)B_(6)处理最小。本研究认为:留茬8 cm,施150 kg N·hm^(-2)+150 kg P_(2)O_(5)·hm^(-2)氮磷肥对实现河西地区豆禾混播草地物种和谐共存及群落结构的长期稳定具有良好效果。

To explore the ecological mechanism of the effects of mowing and fertilization on the stability of legume-grass mixtures in Hexi region.In this study,the mixed pastures established by Medicago sativa,Bromus inermis,and Elytrigia elongata was used as the object.Three stubble heights(5 cm(A_(1)),8 cm(A_(2))and 11 cm(A_(3)))and six fertilizer treatments(CK(B_(1)),150 kg P_(2)O_(5)·hm^(-2)(B_(2)),75 kg N·hm^(-2)+225 kg P_(2)O_(5)·hm^(-2)(B_(3)),150 kg N·hm^(-2)+150 kg P_(2)O_(5)·hm^(-2)(B_(4)),150 kg N·hm^(-2)(B_(5)),225 kg N·hm^(-2)+75 kg P_(2)O_(5)·hm^(-2)(B_(6)))were set.We analyzed the niche characteristics of various species.We found that:compared with stubble height,the importance values of forages were more sensitive to fertilization response,however increasing stubble height could increase the importance values of B.inermis and control the excessively high importance values of M.sativa,among which A_(2)B_(3) treatment had the best effect.A_(1) could increase the niche breadth of each forage,and A_(1)B_(4) was the largest in the third crop.The minimum niche overlaps of M.sativa and B.inermis,M.sativa and E.elongata,B.inermis and E.elongata were A_(2)B_(6),A_(2)B_(1),and A_(2)B_(6) in the second crop,respectively.This study points out:stubble height 8 cm and apply 150 kg N·hm^(-2)+150 kg P_(2)O_(5)·hm^(-2) nitrogen and phosphorus contributes to the harmonious coexistence of species and long-term stability of community structure in legume-grass mixtures in Hexi region.