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1.
高寒草地温室气体排放研究已成为高寒草地与气候变化关系的重要议题之一,但目前的研究多集中于单种类型草地的温室气体通量研究,缺乏多种草地类型间的比较。本研究于2009年以高寒草甸、栽培草地和高寒灌丛为研究对象,利用静态箱法研究3种草地的CH_4、CO_2和N_2O通量特征。结果显示,天然高寒草甸、栽培草地和高寒灌丛是大气CH_4的汇,大气CO_2和N_2O的源,其CH4通量分别为-21.4、-28.1和-41.1μg·m~(-2)·h~(-1);CO_2通量分别为360.6、447.9和475.1 mg·m-2·h-1;N_2O通量分别为34.2、51.6和50.6μg·m~(-2)·h~(-1)。生长季的高寒草地CH_4吸收占全年的42.4%~45.6%,生长季的CO_2和N_2O排放量分别占全年的64.1%~67.8%和37.9%~66.7%。土壤5 cm温度与CH_4、CO_2、N_2O通量分别呈负相关、正相关和正相关关系,除高寒草甸CH_4通量外土壤5 cm与其他草地温室气体通量均达到显著水平(P0.01);土壤湿度与草地CH_4和CO_2通量呈正相关,与N_2O通量呈负相关,但仅与高寒草地CH_4和CO_2相关性达到显著水平(P0.01)。土壤呼吸温度敏感性大小(Q10)值显示,CO_2通量较CH_4和N_2O通量对温度更为敏感。将3种草地的CH_4、N_2O通量值换算为等量CO_2后发现草地温室气体通量造成的温室效应表现为高寒灌丛栽培草地高寒草甸。 相似文献
2.
利用LI-8100A土壤碳通量测量系统对热带城市草地土壤CO_2通量进行定点系统监测,阐明土壤CO_2通量时间变化特征及其对环境因子响应。结果表明,1)草坪绿地土壤CO_2通量日变化呈单峰曲线,最高值一般出现在09:00-16:00,不同月份、不同天气条件有所差异;土壤CO_2通量的日平均值6月份最大,为4.27μmol·(m~2·s)~(-1),12月份最小,为0.86μmol·(m~2·s)~(-1),年内变化趋势总体呈单峰曲线;2)草坪绿地土壤CO_2通量变化与气温、土壤温度呈显著的正相关关系(P0.05),而与土壤体积含水量之间的关系较为复杂,相关性不显著(P0.05)。3)较小强度降水对土壤CO_2通量变化影响较小,而强降雨对土壤CO_2通量变化产生明显的挤出作用。一次大的降水过程初期,随着降水量增加,土壤呼吸速率持续增大;而当土壤水分含量较高时,降雨则对土壤呼吸产生抑制作用。 相似文献
3.
甲烷(CH4)是1种主要的温室气体。为了探究温性草甸草原放牧系统的CH4通量特征，本研究设置了围封(CK)、持续放牧(CG)、早期休牧(R1)、中期休牧(R2)以及晚期休牧(R3)等多个处理，通过监测放牧季的土壤CH4通量并测定放牧绵羊的CH4排放量，计算了草地土壤的CH4“碳汇”贡献度。结果表明：草地土壤在不同日期吸收CH4的通量范围是25.37～79.46μg·m-2·h-1,吸收值在不同处理之间差异极显著(P<0.001),且CG,R1,R2和R3处理均高于CK处理；放牧绵羊的CH4排放量在R3处理中最高而在R2处理中最低(P<0.001);草地土壤吸收CH4-C的贡献度在不同处理之间也具有极显著的差异(P<0.001),CG处理最高而R1处理最低。综上所述，季节性休牧既可以增加草地土壤对CH4的吸收，也会减少绵羊的CH 相似文献
4.
草地不同利用方式和土壤水热条件对温室气体排放具有重要影响。冻融期是草地N2O排放的关键期。本研究以内蒙古温带典型草原为研究对象，设置1979年以来禁牧(1979禁牧)和1999年以来禁牧(1999禁牧)两个处理组，以持续放牧样地为对照，分别于2019-2021年的两个冻融期(11月-次年4月)，利用传感器和气体原位采集装置对不同深度土壤剖面的水分、温度和N2O浓度进行监测，并用静态箱法测定N2O通量。结果显示，冻融期土壤剖面N2O浓度随着水热增加而急剧增加，不同深度土壤剖面N2O浓度差异不显著(P> 0.05)，放牧草原土壤剖面的N2O浓度(0.76 cm3·m-3)均显著高于禁牧草原(1979禁牧：0.51 cm3·m-3,1999禁牧：0.58 cm3·m-3)(P <0.05)。放牧样地N2O通量[8.30μg·(m2·h)-1]显著高于1979禁牧处理[–0.72μg·(... 相似文献
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试验采用密闭箱技术对呼伦贝尔地区种植的苜蓿人工草地进行碳通量研究,采用反硝化-分解作用模型(DNDC)进行模拟。试验结果表明:对苜蓿人工草地CO2通量24h连续观测发现,CO2通量全天变化的平均值(238.15mg/(m2·h)与11∶00(245.32mg/(m2·h)的通量变化值接近,试验从早上9∶00~11∶00进行温室气体的采集方法合理、可行;在整个生长季变化表明,7、8月CO2通量变化较显著(P0.05),且受到降水的影响较大,伴随降水的发生,CO2通量会发生不同幅度的变化,土壤温度和含水量对CO2通量有一定的影响(r0.45,P0.05);通过DNDC模型的模拟,能较好的反映苜蓿人工草地CO2通量的变化情况,但模拟结果数值普遍有些偏高。 相似文献
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在中国科学院海北高寒草甸生态系统定位研究站,利用静态密闭箱-气相色谱法,连续两年(2013,2014年)进行了高寒草甸N_2O排放速率及其对降水和气温的响应特征研究。结果表明:高寒草地N_2O年平均排放速率为32.4±3.1μg/(m~2·h),生长季排放速率为41.1±4.3μg/(m2·h),明显高于休眠季的排放速率20.2±3.2μg/(m~2·h);不同采样时期N_2O排放速率具有极显著差异;气温与N_2O的排放速率之间存在显著正相关关系(R=0.52),随着日平均气温增加,高寒草甸土壤N_2O排放速率逐渐提高;降水量与N_2O排放通量之间存在较弱的负相关关系。在未来全球增温的气候情景下,高寒草地土壤N_2O排放量将呈现上升的趋势。 相似文献
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《草业学报》2021,(1)
为探寻宁夏典型温性天然草地土壤有机碳及活性组分变异及储量特征,以宁夏4种典型的天然草地(温性草甸草原、温性草原、温性草原化荒漠和温性荒漠草原)为研究对象,采用野外调查和室内分析相结合的方法,对宁夏全区49个固定监测点,土壤有机碳及其活性有机碳组分(易氧化有机碳、微生物生物量碳和水溶性有机碳)进行采样和室内分析。结果表明:1)宁夏草甸草原、温性草原、草原化荒漠和荒漠草原4种天然草地,0～40 cm土层深度土壤有机碳含量分别为34. 23、12. 84、5. 76和3. 82 g·kg~(-1);单位面积土壤有机碳储量分别为:13. 43、5. 75、2. 58和2. 29 kg·m~(-2),且均表现为:草甸草原温性草原草原化荒漠荒漠草原。2)4种典型天然草地土样易氧化有机碳含量为0. 75～7. 43 g·kg~(-1),土壤微生物生物量碳含量为102. 52～554. 77 mg·kg~(-1),土壤水溶性有机碳含量为69. 66～89. 61 mg·kg~(-1),均表现为:草甸草原温性草原草原化荒漠荒漠草原。4种草地类型土壤易氧化有机碳储量分别为2. 56、1. 44、0. 62和0. 48 kg·m~(-2);土壤微生物生物量碳储量分别为:218. 31、170. 50、81. 99和68. 26g·m~(-2),均为草甸草原显著高于其他3种草地类型(P0. 05);水溶性有机碳储量分别为34. 36、35. 21、37. 22和43. 14 g·m~(-2),表现为荒漠草原显著大于其他3种草地类型(P0. 05)。3)4种典型天然草地易氧化有机碳分配比为18. 42%～29. 72%,温性草原最高;微生物生物量碳分配比为1. 54%～3. 83%,草甸草原最低;水溶性有机碳分配比为0. 23%～2. 01%,表现为:荒漠草原草原化荒漠温性草原草甸草原,且均存在显著性差异(P0. 05)。4)土壤有机碳储量与土壤易氧化有机碳储量、微生物生物量碳储量、全氮、全磷和全钾含量呈显著(P0. 05)或极显著(P0. 01)正相关关系;与土壤水溶性有机碳储量、土壤容重及pH值呈显著(P0. 05)或极显著(P0. 01)的负相关关系。因此可见,宁夏荒漠草原土壤有机碳稳定性最差,温性草原土壤有机碳活性大,土壤有机碳碳库的生物可利用性最高,宁夏温性天然草地土壤有机碳储量大,不应被低估。 相似文献
8.
2012年生长季(6~9月)采用封闭箱法研究不同放牧强度对典型草原CO_2通量日变化的影响,结果表明:重度放牧地生物量显著低于其它放牧样地。各放牧样地草地生态系统CO_2净气体交换(NEE)在夜晚(21∶00)均为正值(碳源),不放牧地与中度放牧地在白天为负值(碳汇),但8月份重度放牧地在13∶00时转化为碳源,NEE为0.42μmol CO_2/m~2·s,而在17∶00时NEE只有-0.03μmol CO_2/m~2·s,是极弱的碳汇。放牧季开始后,重度放牧草地生态系统CO_2总固定量、生态系统呼吸和NEE均显著低于不放牧与中度放牧地。随着放牧时间增加,重度放牧地固定CO_2的能力逐渐减弱,重度放牧改变了草地植被碳的汇/源状态。 相似文献
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本研究以我国北方天然草地毒草醉马草(Achnatherum inebrians)为研究对象,在甘肃省肃南县大河乡公路两侧对其种群数量较大的区域开展了草甘磷和重耙对比灭杀试验;在此基础上,采用随机区组试验设计,选择补播的优良牧草种类,总结了草地补播改良效果以及技术。结果表明,10%草甘磷防除效果超过98%,推荐使用剂量150~190g·667m~(-2)为宜;重耙灭杀醉马草防除效果超过90%,推荐重耙措施为30cm深度为宜。退化草地补播改良结果表明,浅翻耕条播、浅翻耕撒播、行内松土补播牧草的组合Ⅴ[垂穗披碱草(Elymus nutans)1kg·667m~(-2)+紫羊茅(Festuca rubra)0.5kg·667 m~(-2)+草地早熟禾(Poa pratensis)0.3kg·667 m~(-2)+小冠花(Coronilla varia)0.2kg·667m~(-2)]和组合Ⅵ[垂穗披碱草1kg·667m~(-2)+紫羊茅0.5kg·667m~(-2)+草地早熟禾0.2kg·667m~(-2)+小冠花0.3kg·667m~(-2)]的成活率分别为85%和73%,91%和87%,87%和75%,表现出较强的适应性。退化草地牧草补播的最适宜播种深度为1~4cm,当播种深度为0和4~8cm时,出苗率和成活率均较低。与不动土撒播相比,浅翻耕条播、行内松土补播牧草的组合Ⅴ和Ⅵ可有效改善土壤养分状况,使补播牧草高度、密度及生物量显著增加,可以在天然退化草地的生态恢复中推广应用。 相似文献
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对青海湖农场退耕还林草地以及耕地和天然草地的土壤有机碳(SOC)、全氮(TN)含量及储量、无机氮(N_(inorg))含量、土壤pH等基础理化指标进行了测定分析。结果表明:退耕(还林草)地与耕地和天然草地土壤均偏碱性;退耕地及天然草地土壤容重及N_(inorg)含量均低于耕地;退耕地和天然草地0~5 cm土层C/N显著高于耕地;退耕地和耕地0~5,5~10,10~20 cm土层的SOC和TN含量低于天然草地;退耕还林草9年后各土层SOC和TN含量与耕地相比差异不显著,说明青海湖区持续耕作60多年后,要恢复土壤肥力仍需较长时间;对于0~30 cm土层的SOC及TN储量,退耕地和天然草地与耕地无显著差异,而退耕地与天然草地之间差异显著(P<0.05);耕地、退耕地以及天然草地0~20 cm土壤SOC含量分别占0~30 cm土层SOC储量的68.7%,72.9%和78.6%;0~20 cm土层TN含量分别占0~30 cm土层TN储量的68.7%,72.7%和78.2%;与天然草地相比,按耕地开垦60年计算,0~30 cm耕层内,C的损失率为0.11 t C·a^(-1)·hm^(-2),N的损失率为0.015 t N·a^(-1)·hm^(-2);土壤C和N含量与容重共同决定C和N储量的大小,因此土壤容重是影响土壤质量的重要因素之一。 相似文献
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Ovine scrapie was first recorded in Cyprus in 1985. Subsequently four dairy goats kept in two mixed flocks with affected sheep developed characteristic clinical signs similar to those seen in sheep. Fifteen goats from the two flocks were examined histologically and neurological lesions consistent with a diagnosis of scrapie were found in the four animals and in three others which had subsequently developed early neurological signs. These lesions were similar to those of naturally-affected sheep although neuronal degeneration and vacuolation were more severe in some cases. 相似文献
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Slocombe JO McMillan I 《The Canadian veterinary journal. La revue veterinaire canadienne》1985,26(10):323-327
In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal.
Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection.
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Slocombe JO McMillan I 《The Canadian veterinary journal. La revue veterinaire canadienne》1984,25(9):347-350
In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario.
Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously.
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Slocombe JO Villeneuve A 《The Canadian veterinary journal. La revue veterinaire canadienne》1993,34(10):630-633
In late November 1991, 1883 clinics in Canada were sent a questionnaire to assess the status of Dirofilaria immitis in dogs in 1991 and there was a 60.0% response. There were 344,031 dogs tested for heart-worm (HW), 627 were found infected and the prevalence of HW infection was 0.18%. There were 417 dogs with HW in Ontario, 116 in Manitoba, 38 in Quebec, 53 in British Columbia, three in Alberta, and one in Nova Scotia. In British Columbia, all of the infected dogs but one were from the Okanagan valley which, as from 1991, is a new focus of infection in Canada. Most dogs with HW had not been on preventive medication in 1990, and the prevalence among dogs tested and unprotected was 0.59%. That prevalence was considerably higher in endemic areas. Companion dogs, over three years of age and maintained primarily outdoors in rural areas, were most frequently infected. One cat was diagnosed with D. immitis and 33 dogs had Dipetalonema reconditium. 相似文献
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Owen J Slocombe D McMillan I 《The Canadian veterinary journal. La revue veterinaire canadienne》1986,27(9):324-328
In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%).
Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada.
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Slocombe JO McMillan I 《The Canadian veterinary journal. La revue veterinaire canadienne》1989,30(6):504-508
In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%). 相似文献
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In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated.
Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively.
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