【作者】 鱼小军；

【导师】 龙瑞军；

【作者基本信息】 甘肃农业大学 ， 草业科学， 2010， 博士

【摘要】 青藏高原高寒草地是我国重要的牧区之一,也是广大藏族同胞赖以生存的基础。其生态系统的稳定不仅对我国东部和西南部气候产生巨大影响,而且对北半球甚至全球的气候产生显著影响。然而,日趋严重的草地退化问题已给青藏高原及其周边地区的生态环境和社会经济的可持续发展构成了严重威胁。在青藏高原,牦牛粪常作为牧民生活最依赖的燃料从草地上被捡走后,燃烧牦牛粪使灌丛草地免于砍伐;同时,致使高寒草地损失了养分、种子。关于牦牛粪对高寒草地的健康是否具有维系作用,未见报道。为此,本文系统地研究了如下内容:1)调查青藏高原牧区牧民燃烧的牛粪总量,客观评价燃烧牛粪能使多大面积的灌丛草地免于砍伐和破坏,量化其草地生态系统因牦牛粪被捡走而流失的养分;2)牦牛粪的堆积对青藏高原高寒草地生态系统的影响;3)观测牦牛的排粪特性,研究牦牛和绵羊的消化率特性,量化多少头牦牛产生的粪可满足每人每年的需要量;4)研究牦牛和绵羊对高寒草地牧草种子的消化道传播机制与过程,以及其经过消化道后的萌发情况;5)放牧牦牛和绵羊对青藏高原高寒草地的影响。得出了如下主要结果:4月底牦牛粪含水量为75%,全氮、全磷、全钾和有机质含量分别为1.33%、0.159%、0.626%和51.8%,pH为6.84。在天祝高寒草地上,牦牛粪堆积一年后,牦牛粪仍然完好的存在于草地上。牦牛粪的堆积有利于高寒草地土壤物理性质的改善,能显著降低土壤容重和增大土壤含水量。牦牛粪的堆积增加了牛粪下面和距牛粪堆10cm远土壤的速效氮、全氮、速效磷、全磷、速效钾和有机质含量。在牦牛粪堆积的当年,牛粪堆积并未促进周围植物的生长;在次年,促进了周围植物的生长。堆积一年5个月后,粪堆下面植物仍然枯死;牦牛粪旁边10 cm的总产草显著高于距离牛粪50cm处的对照。牦牛粪覆盖草地的第一、二年,覆盖造成产草量的降低。牦牛粪的热值为15.38～17.89 KJ/g,其平均值为16.47 KJ/g。在供试的21种灌木的热值,为17.80～24.26 KJ/g,其平均值为21.22 KJ/g。甘肃省天祝县抓喜秀龙乡、甘肃省肃南县皇城镇、青海省玛沁县大武镇和西藏自治区那曲古露镇4地,牧民平均每人每年的牛粪燃烧量分别为2182、590、9233和3595kg,上述4地平均每人每年因燃烧牦牛粪而减少砍伐的灌木量分别为1702、460、7202和2804kg或面积为1229、332、5200和2025 m2的灌木。天祝高寒草地全年放牧的牦牛,粪中的全磷、全氮、全钾和有机碳含量分别为0.4974 %、2.031 %、0.665 %和39.41 %。天祝高寒草地全年放牧的绵羊,粪中的全磷、全氮、全钾和有机碳含量分别为0.5026 %、1.954 %、0.707 %和41.14 %。由于燃烧牦牛粪,上述4地区牧民平均每人每年燃烧损失的P为11、3、46和18 kg,N为44、12、188和73 kg,K为15、4、61和24 kg。在天祝高寒草地,综合全年的排粪特性,整群牦牛的排粪干重平均为2.0 kg/d·头。5.2头、1.5头、12.7头和5.0头牦牛,分别可满足上述4地区牧民平均每人燃烧牛粪的需要。4月底,天祝县抓喜秀龙乡,草地上放牧牦牛7 h 30 min,草地上放牧占全天时间的31.25%;草地上排粪占全天总量的35.65%。按整群牦牛计算,平均每头牦牛排粪覆盖面积为0.194 m2,其中平均排粪覆盖草地面积约0.078 m2/ d·头。牦牛在10月份和2月份对混合草的表观消化率分别为63.22%和61.81%,1月份对青稞秸秆的表观消化率为61.81%,4月份对燕麦青干草的表观消化率为59.42%。绵羊在10月份和2月份对混合草的表观消化率分别为57.64%和53.68%,1月份和4月份对燕麦青干草的表观消化率分别为57.25%和55.18%。种子经过牦牛和绵羊消化道后的回收率因家畜和植物种类不同而异。经过牦牛消化道后回收率大于20%的为黄花棘豆、马蔺、珠芽蓼、珠芽、皱叶酸模、披针叶黄华、狼毒、阴山扁蓿豆、醉马草、双柱头藨草、密花香薷、灰绿藜、镰形棘豆、华扁穗草、水葱、红棕苔草、无脉苔草、轮叶马先蒿、多茎委陵菜和车前;回收率小于1%的为溪畔银莲花和红花岩黄芪;回收率在1%～10%范围内的为垂穗披碱草、铁棒槌、迷果芹、高山韭、糙毛鹅冠草、线叶嵩草、窄果苔草、无芒雀麦、紫羊茅和赖草;回收率在10%～20%的为青藏苔草和砂生槐。经过绵羊消化道后种子回收率大于20%的为黄花棘豆、披针叶黄华和镰形棘豆;回收率小于1%的为垂穗披碱草、铁棒槌、迷果芹、糙毛鹅冠草、红花岩黄芪、溪畔银莲花、无芒雀麦和紫羊茅;回收率在1%～10%范围内的为青藏苔草、马蔺、珠芽蓼、珠芽、皱叶酸模、狼毒、高山韭、线叶嵩草、醉马草和砂生槐;回收率在10%～20%的为无脉苔草、扁蓿豆、轮叶马先蒿、双柱头藨草、密花香薷、灰绿藜、华扁穗草、水葱、红棕苔草和车前。种子经过牦牛和绵羊消化道后,发芽率升高的有无脉苔草、红棕苔草、镰形棘豆和灰绿藜和双柱头藨草;经过牦牛消化道后种子发芽率提高而经绵羊消化道未提高的有珠芽蓼、线叶嵩草和华扁穗草;发芽率明显降低的有禾草、黄花棘豆、皱叶酸模、铁棒槌、迷果芹、高山韭、轮叶马先蒿、披针叶黄华、密花香薷和车前,保持不变的有青藏苔草、马蔺、珠芽、狼毒、砂生槐、阴山扁蓿豆和水葱。在天祝高寒草地11～4月份的牦牛粪中,共鉴定出43种植物,平均每块牦牛粪中的种子数为45粒。通过2008年和2009年连续两年的研究,在中度放牧牦牛、中度放牧绵羊、中度牦牛绵羊混合放牧的3块放牧强度相近的样地中,单纯放牧绵羊草地的产草量明显高于牛羊混合放牧和单纯放牧牦牛的草地,而牛羊混合放牧草地的产草量也明显高于单纯放牧牦牛的草地。相似的结果还表现在植物高度、枝条总密度上。中度放牧绵羊、中度牦牛绵羊混合放牧、中度放牧牦牛的3样地产草量分别为581 g/m2、476 g/m2、411g/m2。中度放牧绵羊的草地植被群落的Shanno-Wiener多样性指数为4.5825,明显低于中度放牧牛羊和中度放牧牦牛的草地;牛羊混合放牧草地,在中度放牧下植被群落的Shanno-Wiener多样性指数最大,重度放牧下最小。中度放牧牦牛草地上植物种数多于中度放牧牛羊和中度放牧绵羊草地。混合放牧牛羊草地,中度放牧条件下物种数最大,重度放牧条件下最小。中度放牧牦牛草地Pielou均匀性指数最高,其次为中度放牧牛羊、中度放牧绵羊。中度放牧绵羊草地土壤较为松软,中度放牧牦牛草地土壤紧实度较高,中度放牧牛羊草地居于二者之间。土壤速效钾、速效氮、速效磷、全氮、全磷含量最高为中度放牧绵羊草地,其次为中度放牧牛羊草地,最低为中度放牧牦牛草地。土壤有机质含量为中度放牧羊草地显著高于中度放牧牛羊和中度放牧牦牛草地,而中度放牧牛羊草地低于中度放牧牦牛草地,但差异不显著。中度放牧绵羊草地土壤中性磷酸酶、过氧化氢酶和土壤尿酶活性均高于中度放牧牛羊、中度放牧牦牛草地。除0～10cm土壤尿酶活性外,中度放牧牛羊草地土壤中性磷酸酶、过氧化氢酶和土壤尿酶活性均高于中度放牧牦牛草地。综上所述,在青藏高原高寒草地上,燃烧牦牛粪使灌丛草地免于砍伐,间接地保护了灌丛草地。冷季牦牛粪的堆积造成至少2年产草量的降低,而牦牛粪的捡走减轻了牛粪堆积对草地的危害。由于牦牛粪中含有较多的N、P、K等养分和可萌发的种子,因此捡走牦牛粪引起草地生态系统中养分和种子的流失,且这种流失作用随着放牧强度的增大呈增加趋势,这使牦牛粪对青藏高原高寒草地健康的维系作用弱化。在草地上将牦牛粪进行破碎化处理,或进行堆肥后归还草地,方可解决牛粪堆积与捡走牛粪的矛盾,使牦牛粪对青藏高原高寒草地健康的维系作用得以保持。由于牦牛粪绝大多数被捡走,而绵羊粪绝大多数留在草地上,这是导致放牧绵羊更有益于青藏高原高寒草地健康的部分原因。基于上述研究,本文提出了“多绵羊少牦牛”高寒草地放牧畜牧业经营管理模式。更多还原

【Abstract】 Alpine grassland on Tibetan plateau is one of important pastoral areas in China and is the general basis for the survival of Tibetan people. The stability of alpine grassland ecosystem has enormous impact on the climate of Eastern and Southwestern China, but also has a significant impact on the climate of northern hemisphere, even the world’s climate. However, the increasingly serious problem of grassland degradation has posed a serious threat on the Tibetan Plateau even surrounding area’s ecological environment and socio-economic sustainable development.On Tibet Plateau, yak dung was collected from the alpine grassland to fuel and was herders’reliable fuel fueled for cooking, making tea and warming. Collecting dung lead to nutrients and seeds decrease in alpine grassland, but burning yak dung reduced bush logging in the shrub grassland. In fact, it has protected the shrub grassland by fueling the yak dung. The yak dung has the role of maintenance for Qinghai-Tibet Plateau alpine grassland health, which has not been reported in literature. So a series experimental tests were studied systematically which included: 1) investigating the total volume of cow dung systematically fueled by herders in Tibetan plateau pasturing area, study how much areas shrub grassland is protected from damage and destruction with fueling yak dung by investigating yak dung amount fueled and testing calorific value of yank dung and shrubs, quantizing how much grassland ecosystem nutrients were lost by collecting yak dung; 2) the influence of yak dung accumulation on alpine grassland ecosystem by artificial accumulated yak dung on alpine grassland; 3) observing the defecation characteristics of yak, studying the digestibility characteristics of yak and sheep, quantizing how much cow dung needed one person per year as fuel; 4) the mechanism and process of endozoochorous seed dispersal by yak and sheep in Tianzhu alpine grassland on alpine grassland seeds, and whether the seeds defecated by yak and sheep are easily germinating; 5) the influence of grazing system which grazing yaks and sheep only and mixed on grassland soil, species biodiversity and forage product. The main results obtained are as followed.Moisture content of the yak dung applied for accumulation experiment was 75%. Total N, P and K was 1.33%, 0.159% and 0.626%, total organic matter was 51.87%, pH was 6.84. Dung was still present in the field after one year’accumulation. Yak dung (treatment) decreased soil pH, increased soil EC, improved soil physical properties of alpine meadow, reduced soil bulk density and increased soil moisture significantly. The accumulation of the yak dung increased the available N, total N, available P, total P, available K and organic matter content of soil under yak dung and around dung 10 cm.Yak dung accumulation caused above-ground plants death under dung for poor oxygen content and less light in the first year. After yak dung accumulating one year and five months, total forage product around dung 10 cm was significantly higher than the control. For yak dung patch overlapped plants and caused the death of forage, its accumulation caused forage product decline. It is a dilemma that moving down yak dung from alpine grassland made soil nutrient and soil seed losses while accumulation made forage production decreased.The calorific value of yak dung ranged from 15.38 to 17.89 KJ / g, and the average is 16.47 KJ / g. Among 21 species shrubs tested, the calorific value ranged from 17.80 to 24.26 KJ / g, and the average is 21.22 KJ / g. The average volume of yak dung fueled annual each herdsman in Zhuaxixiulong Township of Tianzhu County in Gansu Province, Huangcheng Township of Sunan County in Gansu Province, Dawu Township of Maqin County in Qinghai Province and GuluTownship of Naqu County in Tibet was 2182 kg, 590 kg, 9233 kg and 3595 kg, respectively. The average volume of shrub yields which are reduced by fueling yak dung in the four places were 1702, 460, 7202 and 2804 kg or area equivalent 1229, 332, 5200 and 2025 m2.The monthly average of total phosphorus, total nitrogen, total potassium and total organic carbon content in yak dung is 0.4974%, 2.031%, 0.665% and 39.41%, while which in sheep dung is 0.5026 %, 1.954 %, 0.707 % and 41.14 %, respectively. Approximately, 11, 3, 46 and 18 kg P, 44, 12, 188 and 73 kg N, 15, 4, 61 and 24 kg K was fueled each herdsman annually in four places mentioned frontly, respectively.Integrating the defecation volume of whole year, the annual defecation amount of yak in cluster was 2.0 kg / d ? head. So, 5.2, 1.5, 12.7 and 5.0 yaks can meet herder’s yak dung needs for four places mentioned frontly, respectively.At the end of April, in Zhaxixiulong Township of Tianzhu County, grazing time on the grassland is 7 hours and 30 minutes. The proportion of dung weight defecated on the grassland was 35.65 percent. According to whole group of yaks defecation, total occupation area was per yak defecated was 0.194m2, and grassland area covered by each yak’s defecation per day was about 0.078 m2.Yak apparent digestibility of mixed-grass in October and February was 63.22 % and 61.81%, of highland barley straw in January was 61.81%, and of oat hay in April was 59.42%. Sheep apparent digestibility of mixed grass in October and February was 53.68% and 57.64%, of oat hay in January and April were 57.25% and 55.18%.Recoverage proportion of alpine grassland plant seeds defecated by yak and sheep was different by animal and species. Oxytropis ochrocephala, Iris lacteal, Polygonum viviparnm, Rumex crispus, Thermopsis lanceolata, Stellera chamaejasme, Pocockia ruthenia, Achnatherum inebrians, Scirpus distigmaticus, Elsholtzia densa, Chenopodium glaucum, O. falcate, Blysmus sinocompressus, Scirpus validus, Carex przewalski, C. enervis, Pedicularis verticillata, P. multicaulis, Plantago asiatica seeds and bulbil of P. viviparnm recoverage propoion fefacated by yak was greater than 20 percent; Anemone rivularis and Hedysarum multifugum seeds recoverage propoion was smaller than one percent; Elymus nutans, Aconitum szechenyianum, Sphallerocarpus gracilis, Allium sikkimense, Roegneria hirsute, Kobresia capillifolia, C. angustifructus, Bromus inermis, Festuca ruba and Leymus secalinum seeds recoverage propoion was range from 1 to 10 percent; and C. moorcroftii and Sophora moocroftiana seeds recoverage proportion was range from 10 to 20 percent.O. ochrocephala, T. lanceolate and O. falcata seeds recoverage propoion fefacated by sheep was greater than 20 percent, E. nutans, A. szechenyianum, S. gracilis, R. hirsute, H. multifugum, A. rivularis, B. inermis and F. ruba seeds recoverage propoion was smaller than one percent, and C. moorcroftii, I. lacteal, R. crispus, S. chamaejasme, A. sikkimense, K. capillifolia, A. inebrians, S. moocroftiana and P. viviparnm seeds and Bulbil of P. viviparnm seeds recoverage propoion was range from 1 to 10 percent, C. enervis, P. ruthenia, P. verticillata, S. distigmaticus, E. densa, C. glaucum, B. sinocompressus, S. validus, C. przewalski and P. asiatica seeds recoverage proportion was range from 10 to 20 percent.Seed of C. enervis, C. przewalski, O. falcate, C. glaucum and S. distigmaticus defecated by yak and sheep germination was promoted. P. viviparnm, K. capillifolia and B. sinocompressus seeds germination was promoted passed yak’s digestive tract but that was not passed sheep’s’. Grasses, O. ochrocephala, R. crispus, A. szechenyianum, A. sikkimense, P. verticillata, T. lanceolata, E. densa and P. asiatica seeds germination was reduced, and seeds of C. moorcroftii, I. lacteal, S. chamaejasme, S. moocroftiana, P. ruthenia and S. Validus seeds, and P. viviparnm bulbil germination was unchanged.There are 43 species identified in yak dung from Nov. to April, and there are 45 grain seeds per piece of yak dung.In three grassland plots grazed with similar intensity including grazing yak moderately, and grazing sheep moderately, whether in 2008 or 2009, the forage yield of plot only grazing sheep was higher than the remaining two, and which of grazing yak and sheep was higher than the plot grazing yak he yak The average forage yield of 2008 and 2009 on grazing sheep only, yak and sheep, and only yak is 581, 476 and 411 g/m2, respectively. Similar results were appeared in plant height and total shoot density.The Shannon-Wiener diversity index of the grassland grazing sheep moderately is 4.5825, lower than that of grazing yak and sheep moderately and that of grazing yak moderately, of grazing yak. Similar result appeared in Pielou evenness index .The biggest Shannon-Wiener diversity index appeared on moderate grazing plot and smallest appeared on heavy grazing plot in mixed grazing with yak and sheep plots. Species numbers of the grassland grazing yak moderately is more than mixed grazing moderately plot with yak and sheep and grazing sheep moderately. Yak and sheep mixed rangeland, the species number increased firstly, and then decreased as grazing intensity increasing, that is, under moderate grazing the species number was highest.Soil bulk density in plot with grazing sheep moderately was smaller than grazing mixed with yak and sheep, the biggest was the grassland grazing yak moderately. Opposite result appeared in soil available potassium, available nitrogen, available phosphorus, total nitrogen and total phosphorus content. Soil organic matter content in grazing sheep moderately is significantly higher than that of grazing mixed with yak and sheep and grazing yak moderately, while which of grazing yak moderately is higher than that grazing mixed with yak and sheep.Soil neutral phosphatase, catalase and urease enzyme activity in plot with grazing sheep moderately was higher than grazing mixed with yak and sheep, the smallest was the grassland grazing yak moderately except soil urease enzyme activity form 0 to 10 cm.On Tibet Plateau alpine grassland, burning yak dung reduced bush logging, so it has protected the shrub grassland by fueling the yak dung. For accumulation of yak dung defecated in cold season on alpine grassland led to forage product decline at least two years while removed yak dung from alpine grassland made the harm caused by yak dung accumulation eliminated. As there are lots of N, P, K and other components and some germinable seeds in yak dung defecated in cold season, so collecting dung lead to nutrients and seeds losses in alpine grassland, and the losses increased with the growing grazing intensity. Which weakened the maintenance of yak dung for Qinghai-Tibet Plateau alpine grassland health. Break down yak dung on alpine grassland or return to grassland after composting, which can resolve the dilemma that dung accumulation and removing, and maintenance of yak dung on the alpine grassland health is maintained. Most of yak dung was removed from grassland while sheep dung was keeping, which was one of reasons made grazing sheep was more benefit alpine grassland than grazing yak on Tibet Plateau. So, for above reason,“more sheep and fewer yaks”grazing livestock management mode on alpine grassland was proposed in this paper.更多还原