【作者】 田福平；

【导师】 洪绂曾； 师尚礼；

【作者基本信息】 甘肃农业大学 ， 草业科学， 2015， 博士

【摘要】 为了阐明黄土高原不同单播人工草地碳储量及土壤速效养分的动态特征,以黄土高原主要栽培的紫花苜蓿(Medicago sativa L.)、红豆草(Onobrychis viciaefolia Scop.)、冰草(Agropyron cristatum Gaertn.)、早熟禾(Poa crymophila Keng.)草地和撂荒地(对照)为研究对象。在农业部兰州黄土高原生态环境重点野外科学观测试验站通过长期定点监测实验,研究了生长1~5年的4种单播人工草地及撂荒地的植被碳密度、凋落物碳密度、0-100cm地下生物量碳密度、土壤碳密度、生态系统碳密度与不同单播人工草地的年固碳量,并对4种生长1~5年的单播人工草地及撂荒地的土壤速效氮、速效磷、速效钾与土壤有效铁、有效锰、有效铜和有效锌在0-100cm土层的养分特征进行了分析。该研究有助于揭示全球气候变化背景下的单播人工草地固碳机制,可为我国人工草地生态系统碳循环的研究提供基础数据,同时为阐明黄土高原单播人工草地土壤速效养分特征提供科学参考。主要研究结果如下:1.紫花苜蓿总生物量碳密度在4年龄最高,为18635.8kg C·hm-2。苜蓿草地生态系统碳密度在5年龄最高,为101.96t·hm-2,土壤碳密度占生态系统碳密度的80.6%~90.5%。随着生长年限的增加,紫花苜蓿草地的土壤速效氮含量增加、速效磷含量降低,在0~60cm的土壤速效钾和有效锌、0-20cm的土壤有效铁、0-30cm的土壤有效锰、0-70cm的土壤有效铜均随着紫花苜蓿生长年限的增加而显著降低(P<0.05)。不同生长年限的紫花苜蓿草地土壤速效氮、速效磷、速效钾、0-50cm的有效铁、0-70cm的有效锰和有效铜及0-90cm的有效锌含量均随土层深度的增加而减少。2.红豆草草地总生物量碳密度在3年龄最高,为16454.5kg C·hm-2,其中,地上生物量碳密度占31.6%~56.3%。红豆草草地系统的碳密度也是在3年龄最高,为104.68t·hm-2,土壤碳密度占生态系统碳密度的84.3%~94.4%。红豆草草地在0-30cm的土壤速效氮、0-70cm土壤速效磷和土壤有效锰、0-50cm的土壤速效钾、0-40cm土壤有效铜和0-100cm的土壤有效锌含量均随土层深度的增加而减少。随着生长年限的增加,红豆草草地的速效氮含量在1年龄至4年龄增加,5年龄下降。土壤速效磷、速效钾含量随着红豆草生长年限的增加显著降低(P<0.05)。土壤有效铁和有效锰含量在0-70cm、有效铜和有效锌含量在0-100cm均随着生长年限的增加而降低。3.冰草草地总生物量碳密度在4年龄最高,为7310.7 kg C·hm-2。4年龄冰草草地系统的碳66.18t·hm-288.1%~97.2%的冰草草地,在0-60cm的速效氮、0-100cm的速效磷、0-50cm的速效钾、0-50cm的有效铁、0-60cm的有效锰与有效铜、0-70cm的有效锌含量均随土层深度的增加而减少。随着冰草生长年限的增加,土壤速效氮含量减少,土壤速效磷含量在0-30cm增加,土壤速效钾先减少后增加。0-50cm的土壤有效铁、0-30cm土壤有效锰、0-60cm土壤有效铜及0-30cm土壤有效锌含量均随冰草生长年限的增加而降低。4.早熟禾草地在4年龄总生物量碳密度最高,为6553.0kg C·hm-2,地下生物量碳密度占总生物量碳密度的45.1%~62.0%。4年龄早熟禾草地生态系统的碳密为66.3t·hm-2,且与其它不同生长年限的差异显著(P<0.05),土壤碳密度占生态系统碳密度的90.1%~98.5%。不同生长年限的早熟禾草地速效氮含量在0-60cm、速效磷含量在0-70cm、速效钾含量在0-50cm、有效铁含量在0-100cm、有效锰在0-70cm、有效铜和有效锌在0-60cm均随土层深度的增加而减少。随着早熟禾生长年限的增加,在0-60cm的土壤速效氮、0-50cm的速效磷和速效钾含量均增加,而在0-30cm的有效铁、0-40cm的有效锰、0-100cm有效铜和有效锌含量均随着生长年限的增加而降低。5.撂荒地1年龄总生物量碳密度最高,为969.4kg C·hm-2。撂荒地生态系统碳密度在5年龄为49.0t·hm-2,且与其它不同年限生态系统碳密度差异显著(P<0.05)。撂荒地土壤碳密度占生态系统碳密度的92.3%~98.3%。不同生长年限的撂荒地土壤速效氮、速效磷、速效钾、有效铁和有效锰的含量随着土层深度的增加而减少。在0-40cm的各个土层,有效铜含量与有效锌含量均随土壤深度的增加而有规律的下降。土壤速效氮和速效钾在0-50cm、速效磷在0-30cm、有效铁和有效锌含量在0-30cm、有效锰和有效铜含量在0-50cm的土层均随撂荒年限的增加而增加。6.不同单播人工草地生态系统5年的平均固碳速率从高到低依次为:苜蓿草地(13.04t·hm-2·a-1)>红豆草草地(10.87t·hm-2·a-1)>早熟禾草地(5.17t·hm-2·a-1)>冰草草地(4.79t·hm-2·a-1)>撂荒地(2.46t·hm-2·a-1)。不同单播人工草地的土壤速效氮含量均显著高于撂荒地。其中,苜蓿和红豆草草地1年龄至5年龄的土壤速效氮含量显著高于冰草和早熟禾草地(P<0.05)。随着生长年限的增加,冰草草地、早熟禾草地和撂荒地的土壤速效磷、速效钾含量增加,红豆草和苜蓿草地的土壤速效磷、速效钾含量降低。随着生长年限的增加,不同单播人工草地的土壤有效铁、有效锰、有效铜、有效锌含量降低,其中,豆科牧草紫花苜蓿和红豆草草地降低的幅度均大于禾本科牧草冰草草地和早熟禾草地。撂荒地的土壤有效铁、有效锰、有效铜、有效锌含量随着撂荒年限的增加缓慢升高,但撂荒地土壤速效养分的绝对增加量比较小。本研究为我国黄土高原草地碳储量的计算、固碳机制的研究提供基础数据,同时也为我国黄土高原人工草地的可持续发展和生态环境建设提供理论支持。更多还原

【Abstract】 The current research was conducted to elucidate the carbon storage and soil available nutrient characters of several monoculture artificial grasslands in loess plateau, based on a long-term fixed-point monitoring experiment at the Lanzhou Scientific and Experimental Field Station of Ministry of Agriculture. The four monoculture artificial grasslands are alfalfa(Medicago sativa L.), sainfoin(Onobrychis viciaefolia Scop.), wheatgrass(Agropyron cristatum Gaertn.)and Kentucky Kentucky bluegrass(Poa crymophila Keng.). The abandoned land was selected as control. The following parameters were monitored and determined, vegetation carbon density, litter carbon density, 0-100 cm layer underground biomass carbon density, soil carbon density, ecosystem carbon density, carbon sequestration rate, and soil available N, available P, available K, available Fe, available Mn, available Cu and available Zn in 0-100 cm layer. The results showed scientific reference and strategies for grassland management and utilization of monoculture artificial grassland carbon storage and soil available nutrients in the loess plateau of China.The main results were as follows:1. The total biomass carbon density of 4-year alfalfa grassland was the highest(18635.8 kg C·hm-2). The soil carbon density of 5-year alfalfa grassland ecosystem was the highest(101.96t·hm-2), which accounts for 80.6%-90.5% of ecosystem carbon density. With the increase of growth year, the soil available N, available P in the 0-100 cm layer decreased in alfalfa grassland, and the soil available K in 0-60 cm layer, soil available Fe in 0-20 cm layer, soil available Mn in 0-30 cm layer, soil available Cu in 0-70 cm layer, soil available Zn in 0-60 cm layer decreased significantly(P<0.05).The contents of soil available N, available P and available K in 0-100 cm layer, available Fe in 0-50 cm layer, available Mn and available Cu in 0-70 cm and available Zn in 0-90 cm layer were decreased with the increase of soil depth.2. The total biomass carbon density of 3-year sainfoin grassland was the highest, 16454.5 kg C·hm-2. And the aboveground biomass carbon density in 3-year sainfoin grassland accounted for 31.6%-56.3% of the total biomass carbon density. The 3-year Sainfoin grassland had the highest carbon density, 104.68 t·hm-2. In sainfoin grassland ecosystem, the soil carbon density accounted for 84.3%~94.4% of ecosystem carbon density. The contents of soil available N in 0-30 cm layer, soil available P and soil available Mn in 0-70 cm layer, soil available K in 0-50 cm layer, soil available Cu in 0-40 cm layer and soil available Zn in 0-100 cm layer decreased with the increase of soil depth. With the increase of growth year, from the first to fifth year, the available N content in sainfoin grassland increased, and decreased in the 5th year. And the content of soil available P and available K in sainfoin grassland decreased significantly(P<0.05). The contents of soil available Fe and Mn in 0-70 cm layer, soil available Cu and Zn in 0-100 cm layer increased with the increase of sainfoin growth year.3. The total biomass carbon density of 4-year wheatgrass grassland was the highest, 7310.7kg C·hm. The carbon density of 4-year wheatgrass grassland was the highest, 66.18t·hm-2, and the soil carbon density accounted for 88.1%~97.2% of ecosystem carbon density. The contents of soil available N in 0-60 cm layer, available P in 0-100 cm layer, available K in 0-50 cm layer, available Fe in 0-50 cm layer, available Mn and available Cu in 0-60 cm layer, available Zn in 0-70 cm decreased with the increase of soil depth in different growing years’ wheatgrass grassland. The soil available N decreased with the increase of wheatgrass growth year. In 0-30 cm layer, the soil available P in the same soil layers increased with the increase of growth period. In 0-50 cm layer, the soil available K reduced from the first to third growing year, but in the fourth year and fifth year increased significantly. With the increase of growth year, the contents of soil available Fe in 0-50 cm layer, soil available Mn in 0-30 cm layer, soil available Cu in 0-60 cm layer, soil available Zn in 0-30 cm layer decreased.4. The total biomass of 4-year Kentucky bluegrass grassland was the highest, with the carbon density of 6553.0 kg C·hm-2. The underground biomass carbon density accounts for 45.1%~62.0% of the total biomass carbon density in 4-year Kentucky bluegrass grassland. The highest carbon density(66.3t·hm-2) was found in the fourth year. The soil carbon density accounted for 90.1%-98.5% of the ecosystem carbon density. The soil available N in 0-60 cm layer, available P in 0-70 cm layer, available K in 0-50 cm layer, available Fe in 0-100 cm layer, available Mn in 0-70 cm layer, available Cu and Zn in 0-60 cm layer decreased with the increase of soil depth in different growth year’s Kentucky bluegrass grassland. With the increase of growth year, the soil available N in 0-60 cm layer, available P and available K in 0-50 cm soil layer were significantly increased(P<0.05). The available Fe in 0-30 cm layer, available Mn in 0-40 cm layer, available Cu and Zn in 0-10 cm layer increased with the increase of Kentucky bluegrass growth year.5. The total biomass carbon density in the 1-year abandoned grassland was the highest, 969.4 kg C·hm-2. The ecosystem carbon density in the abandoned grassland increased with the increase of abandon year, and was significantly different with the others(P<0.05). The ecosystem carbon density in the 5-year abandon grassland was 49.0t·hm-2. The ecosystem carbon density accounted for 92.3%-98.3% of the abandoned land soil carbon density. The soil available N, available P and available K, available Fe and Mn in different land abandon years decreased with the increase of soil depth. In 0-40 cm soil, the available Cu and available Zn declined with the increase of soil depth. The soil available N and available K in 0-50 cm layer, available P in 0-30 cm layer, available Fe and Zn in 0-30 cm layer, available Mn and Cu in 0-50 cm layer increased with the increase of land abandon year.6. The average carbon sequestration rate in different5-year monoculture artificial grassland ecosystem from higto low was: alfalfa grassland(13.04t·hm-2·a-1)>sainfoin grassland(10.87t·hm-2·a-1)>Kentucky bluegrass grasslan(5.17t·hm-2·a-1) > wheatgrass grassland(4.79t·hm-2·a-1)>abandoned land(2.46t·hm-2·a-1). The soil availablN in different monoculture artificial grassland was significantly higher than that in the abandoned grassland. Amonthem, from the first to the fifth year, the soil available N in alfalfa grassland and sainfoin grassland was significantlhigher than in wheatgrass grassland and Kentucky bluegrass grassland(P<0.05).With the increase of growth yearthe soil available P and available K in wheatgrass grassland, Kentucky bluegrass grassland and the abandonegrassland increased. And the reduction was observed for soil available P and available K in sainfoin grassland analfalfa grassland, soil available Cu, available Fe, available Mn, available Zn in different monoculture artificiagrassland. However, the alfalfa and sainfoin showed a greater reducing rate than wheatgrass and Kentucky bluegrassThe soil available Fe, available Mn, available Cu, available Zn in the abandoned grassland slightly increased with thgrowth year.The current research can provide basic data and reliable reference for the calculation of grassland carbon storage and carbon sequestration mechanism, as well as provide theoretical support for sustainable development and ecological environmental construction of artificial grassland in the Loess Plateau.更多还原