【作者】 顾梦鹤；

【导师】 杜国祯；

【作者基本信息】 兰州大学 ， 生态学， 2008， 博士

【摘要】 本文以青藏高原高寒草甸三种常见禾本科牧草垂穗披碱草(Elymus nutans)、中华羊茅(Festuca.Sinensis)、羊茅(Festuca ovina)为材料,进行人工混播草地生产力和稳定性及其调控机制的研究。经三年的人工种植,测定和分析研究,得以下几方面的结论。(1)多年生混播草地生长期长,比天然草地提前10天左右返青,与天然草地同步成熟枯黄。(2)草地建成以后,单播草地在第三年开始减产(羊茅单播地例外),2种混播草地和3种混播草地在草地建植第二年和第三年连续高产,草地中的杂草丰富度和杂草生物量变化幅度小,其产量稳定性和种稳定性明显优于单播草地,3种混播草地又优于2种混播草地。在高寒地区,多年生禾草草地可以实现高产的目的,混播组合可以达到稳产的效果。(3)垂穗披碱草、中华羊茅和羊茅在出苗期表现出竞争差异,形成初步的竞争格局,草地建植第二年,幼苗期形成的竞争格局不变,垂穗披碱草占优势。草地建植第三年,羊茅较高的成株存活率增加了其竞争力。(4)混播草地建植第二年,垂穗披碱草/中华羊茅,垂穗披碱草/羊茅混播中,组分种由共享资源、种间无干扰,向着相互竞争的趋势发展;中华羊茅和羊茅混播,相互无干扰;3种物种的竞争等级为垂穗披碱草最强,中华羊茅次之,羊茅最差。草地建植第三年,在混播组合中,组分种之间争夺资源,相互干扰,垂穗披碱草竞争力最强,羊茅第二,中华羊茅第三,物种的竞争等级发生了变化。(5)施肥增强了人工草地群落中垂穗披碱草对水平空间的竞争力,中华羊茅和羊茅对垂直空间的竞争潜力增强,同时降低了草地中杂草生物量及丰富度,有效提高草地生产力的同时,维持了群落的稳定性。(6)刈割降低了草地牧草的产草量,草地中的杂草生物量和杂草丰富度增加,草地的产量稳定性和组分种的稳定性受到影响。在草地建植第一年,不能采取任何形式的利用,但是在建植第二年第三年可以对混播草地进行适度利用(一年刈割两次),适当提前第一次刈割的时间(如开花期),并缩短两次刈割的间隔,留茬以6cm较为适宜。(7)初始播种密度对二龄草地有一定的调控作用,适宜的密度能有效提高草地的产草量,降低草地中的杂草生物量及杂草丰富度,有利于维系草地的产量稳定性和组分稳定性。草地建植第三年,初始密度对牧草产量的调控作用和杂草的抑制作用减小。(8)高寒人工草地建植当年,禾草的侵占力较小,一年生阔叶杂草在草地中(尤其是单播中)占优势地位,其中,萼果香薷,白黎,甘青蒿对草地的危害程度最大;草地建植第二年和第三年,禾草较早返青,在草地中占据了优势,草地中许多杂草频度较低,对草地影响较小,二龄和三龄草地产草量虽然处于高峰期,但是杂草的防治工作不容忽视。更多还原

【Abstract】 The experiment chooses three kinds of perennial grasses,Elymus nutans, Festuca.sinensis and Festuca ovina,which distributed widely in the east of Qinghai-Tibetan alpine meadow to study the productivity and stability of cultivated grassland.The experiment experience three years and the main conclusions as following:1.The re-growth period of cultivated grassland was 10 days ahead of natural pasture and the mature period was same.2.After establishment,the productivity of monoculture perennial grassland began to decrease in the third year(the F.ovina grassland was exceptional).Those of 2 species combined mixtures and 3 species combined mixture keep high production continuously in the second and third years and the change of weed biomass and weed abundance was unconspicuous.The stability of production and component in mixture grassland was better than in monoculture grassland and the 3 species combined mixture was the best. The mixture grassland of perennial grass can achieve the high production in alpine meadow.3.The initial competitive pattern was formed between E.nutans,F. sinensis and F.ovina in the seeding emergence stage and the pattern was not changed in the second year.E.nutans was dominant species and F. sinensis and F.ovina were inferior species in mixtures.In the third year, the highest adult survival increased F.ovina competitive ability in mixture.The adult survival ability of E.nutans,F.sinensis were second and third.4.In E.nutans/F.sinensis and E.nutans/F.ovina mixtures,the combined components utilized the same resource and showed competitive trend in higher seeding densities and the combined components in F.sinensis/F. ovina mixture utilized the same resource in the second year.The competition ability of E.nutans was the strongest,then F.sinensis, followed F.ovina based on Relative Yield Total and Competition Ratio.In the third year,the combined components competed the same resource and interfered each other in three mixtures.The competitive ability of E. nutans was the strongest,F.ovina was the second and F.sinensis was the third. 5.Fertilizer improved the horizontal competitive ability of dominant population(E.nutans)and improve the upright competitive ability of inferior population(F.sinensis and F.ovina).At the same time,it decreased weed biomass and weed abundance in mixture grassland.The production of grassland increased lineally due to fertilizer,the stability can be improved as well.6.Clipping decreased the production and increased the weed biomass and weed abundance in mixtures.The cultivated grassland must not be used by any way in the first year and can be utilized moderately in the second and third year.6cm stubble,2 clipping annually,the first clipping in the blooming stage of grass,the second clipping in the elongating stage of grass was the ideal clipping management for mixture grassland of perennial grass in the alpine region of Gannan area.7.The mezzo seeding density could increase the grassland production effectively and decreased the weed biomass and weed abundance in grassland in the second year.seeding density was effective way to maintain the stability of production and combined component in cultivated grassland. The seeding density effect on the grassland production was minished in the third year.8.In the first year of grassland establishment,the aggressivity of grass was relatively low,and they failed to compete with the weed.The annual weed were compete winners such as E.patrini Garcke,Artemisia tangutica and Chenopodium Album.The seeding grass re-growth early and became dominate population in grassland in the second and third year.The frequency of many weed were decreased and had no serious effect on grassland production.The production of grassland achieved fastigium in the second and third year but the work of weed removed was still a serious question.更多还原