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1.
采用动态密闭气室红外CO2分析法(IRGA)对黄土高原丘陵沟壑区不同地形的封育草地土壤呼吸速率日动态进行了测定,并分析了土壤呼吸与土壤温度、土壤水分、地下生物量和地形间的关系。研究结果显示,草地的土壤呼吸日动态呈单峰曲线,最小值为0.393~1.103 μmol/(m2·s),出现在凌晨;最大值为1.034～1.405 μmol/(m2·s),出现在14时左右,可以用正弦曲线拟合;而且不同样地间土壤呼吸速率与土壤温度间的关系均可用指数函数描述。土壤日均呼吸速率在不同地形的草地间存在差异,平坦草地为1.229 μmol/(m2·s),东北坡15°, 30° 和45° 草地分别为1.138, 1.033和0.890 μmol/(m2·s);西南坡15°, 30° 和45° 草地分别为1.036, 0.859和0.379 μmol/(m2·s);土壤呼吸速率随坡度的增大而减小,东北坡土壤呼吸速率小于西南坡,与不同样地间土壤水分和地下生物量的变化趋势一致,而且研究结果表明土壤呼吸的这种差异主要是受地形影响的土壤水分和地下生物量空间分布差异性决定的,而不同样地间土壤平均温度差异不显著(P>0.05)。  相似文献   

2.
京西百花山区六种植物群落凋落物及土壤呼吸特性研究   总被引：12，自引：0，他引：12  
利用LI-8100开路式土壤碳通量测量系统,对京西百花山区6种植物群落夏季土壤呼吸作用的昼夜变化进行了对比研究.结果表明,6种植物群落土壤呼吸速率日变化成明显的单峰曲线,高峰值一般出现在13∶00～16∶00之间,最低值出现在03∶30～07∶30之间;不同植物群落土壤表层凋落物呼吸对土壤呼吸的贡献率在6.62%～40.83%之间;土壤CO2日释放量以野艾蒿群落最高,其值为254880μmol·m-2·d-1,刺槐群落最低,其值为190944 μmol·m-2·d-1;凋落物CO2日释放量油松群落最大,达91368μmol·m-2·d-1,对土壤呼吸的贡献率为40.83%,而杂类草群落最低,日释放量只有13608μmol·m-2·d-1,对土壤呼吸的贡献率仅为6.62%.相关分析表明,土壤表层凋落物呼吸速率与凋落物厚度、蓄积量成正相关关系(n=6,P＜0.05),而与凋落物有机质含量无明显的相关性;土壤呼吸速率与环境因子具有显著的相关性,其中与土壤表层(5cm)温度呈极显著正相关关系(n=48,P＜0.001),而与近地面气压和CO2浓度呈负相关关系.  相似文献   

3.
中药接骨草光合生理特性研究   总被引：1，自引：0，他引：1  
以野生接骨草(Sambucus chinensis Lind.)为研究对象,用便携式光合仪测定其光响应曲线和CO2响应曲线,同时测得了光合作用其他参数,旨在加深对接骨草光合特性和生理特性的认识,为其高产栽培和管理提供依据.结果表明:接骨草的叶片光饱和点(LSP)为308.97 μmol·m-2·s-1,光补偿点(LCP)为7.94 μmol·m-2·s-1,最大净光合速率(Pmax)为10.24μmol·m-2·s-1,暗呼吸速率(Rd)为-0.27μmol CO2·m-2·s-1,表观量子效率(AQY)为0.03,说明接骨草属喜阴性植物,能较好地利用弱光进行光合作用;CO2补偿点为55.63 μmol·mol-1,CO2饱和点为822.59 μmol·mol-1,羧化效率为0.04,表现出较大光合作用潜力和较广的生存适应能力.  相似文献   

4.
为探究高寒灌-草交错带土壤呼吸动态及影响因素,应用LI-8100A土壤呼吸自动测定系统,对东祁连山典型灌丛-草地交错带土壤呼吸动态及土壤因子进行测定,分析呼吸速率与土壤因子的相互关系。结果表明,整个交错带内土壤呼吸速率的均值介于2.3~7.2 μmol/(m2·s),各样地间土壤呼吸速率大小顺序为珠芽蓼草甸中心(S1)>草甸-金露梅灌丛交错区(MSC1)>金露梅灌丛中心(S2)>金露梅-杜鹃灌丛交错区(MSC2)>杜鹃灌丛中心(S3),S1和MSC1样地的土壤呼吸日变化呈单峰型,峰值出现在14:00,S2、MSC2、S3样地峰型不明显,且日变幅较小,仅为0.3~1.1 μmol/(m2·s);交错带内土壤物理性质和养分储量呈明显的垂直分异规律,土壤呼吸速率与土壤温度、全磷储量呈极显著的正相关(P<0.01),与土壤含水量极显著负相关(P<0.01),与0~20 cm土壤有机碳储量呈显著负相关(P<0.05);拟合分析显示,土壤温度、含水量和全磷储量是土壤呼吸速率的主要限制因子,土壤呼吸与土壤温度拟合系数最高,可解释土壤呼吸空间变异的79.9%。  相似文献   

5.
以滇西北亚高山草甸为研究对象,利用开顶式生长室(OTC)提高土壤温度模拟全球气候变暖,探讨增温对夏季和冬季草地土壤水分,土壤呼吸速率和植被生物量等方面的影响。结果表明:在开顶式生长室的作用下,滇西北亚高山草甸地表年均温度较对照提高了1.56℃,冬季增温效果好于夏季。增温显著提高了草地的地上生物量(P<0.05),比对照高出148.76 g/m~2。同时增温促进了根系向10～20 cm土层扩展。在夏季和冬季,增温处理和对照的土壤呼吸速率均呈现单峰曲线,在14∶00时出现峰值,夏季的最高值为5.66μmol/(m~2·s),冬季为2.79μmol/(m~2·s),夏季的土壤呼吸速率较冬季高出2.87μmol/(m~2·s)。相关性分析表明,土壤呼吸速率与土壤温度呈显著正相关(P<0.05),土壤温度和土壤含水量则呈现出了极显著的负相关(P<0.01)。  相似文献   

6.
为探讨不同土地利用方式对新疆昭苏马场山地草甸土壤呼吸速率的影响,对补播草地(RG)、豆禾混播草地(LG)、天然草地(NG)和农田(CR)进行测定,并分析了土壤呼吸速率与其影响因子间的关系。结果表明:(1)不同利用方式下各样地土壤呼吸日变化均随温度变化呈现出先增加后降低的变化态势,峰值在当地正午时分;月变化在2015年NG和CR呈现双峰值,RG和LG呈现单峰线,各处理均在8月小麦结实期达到最大值;2016年各处理出现峰值的时间不同,RG和LG在小麦的分蘖期达到最大值,NG和CR在小麦开花期达到最大值。(2)监测期内平均土壤呼吸速率由大到小为:NG、RG、CR、LG;各样地土壤呼吸CO_2排放量为:NGCRRGLG。(3)各样地土壤呼吸速率与土壤温度呈指数正相关,与体积含水量呈线性负相关,2015年Q_(10)值排序为RGCRNGLG,2016为NGLGCRRG。因此,补播和建植人工草地降低了土壤呼吸速率,使草地生态系统水热关系更加协调,减少了碳排放量,是昭苏地区退化草地生态恢复较好的选择。  相似文献   

7.
为探寻更加合理的草地利用方式,以甘肃省夏河县桑科乡高寒草原为研究区,分别设置放牧草地,放牧+施肥草地,放牧+划破补播草地、封育草地、人工草地处理,测定不同草地利用方式土壤呼吸的动态变化。结果表明:(1)土壤呼吸速率大小顺序为放牧+施肥人工封育放牧+划破补播放牧,最大值10.41μmol/(m2·s),最小值4.69μmol/(m2·s),日变化和季节变化均呈单峰曲线,日变化峰值出现在13∶00~14∶00,7月各处理土壤呼吸速率达最大。(2)土壤呼吸温度敏感性Q10值为放牧+施肥放牧人工放牧+划破补播封育,最大值1.826,最小值1.157。(3)土壤呼吸与土壤湿度的非线性相关关系P值大小为放牧+划破补播放牧人工封育放牧+施肥。放牧+施肥处理为最优草地利用方式。  相似文献   

8.
以人为控制降雨量和LI-6400便携式光合测定系统控制温度方法,测定分析了降雨量和温度变化对高寒草甸典型组成植物——麻花艽叶片净光合速率及相关生理参数影响。结果显示:麻花艽叶片净光合速率、气孔导度、胞间CO2浓度、蒸腾速率在降雨量增加下较高、自然降雨量下次之、降雨量减少处理下较低;水分利用效率在降雨量增加下较低、自然降雨量下次之、降雨量减少下较高,温度为25℃与15℃下差异不显著。麻花艽叶片净光合速率在光合有效辐射强度为0~800μmol.m-2.s-1时随光合有效辐射强度增加而增加,800~1200μmol.m-2.s-1时达最大,1200~3000μmol.m-2.s-1时变化不大;气孔导度和蒸腾速率随光合有效辐射强度增加而增加;胞间CO2浓度在光合有效辐射强度为0~800μmol.m-2.s-1时随光合有效辐射强度增加而下降,800~3000μmol.m-2.s-1时变化不大;水分利用效率在光合有效辐射强度为0~800μmol.m-2.s-1时随光合有效辐射强度增加而增加,800~3000μmol.m-2.s-1时呈现下降趋势。降雨量减少将使高寒草甸植物叶片净光合作用速率、气孔导度、胞间CO2浓度和蒸腾速率降低。  相似文献   

9.
海拉尔地区苜蓿栽培草地土壤呼吸特性研究   总被引：1，自引：1，他引：0  
使用便携式土壤呼吸测定仪(Li-6400)测定不同苜蓿品种栽培草地的土壤呼吸,并同步测定植株根系形态指标、土壤层温度、大气温度和土壤含水量。结果表明,黄花苜蓿(Medicago falcata)、龙牧801(M.sativacv.Longmu801)和肇东苜蓿(M.sativacv.Zhaodong)草地土壤呼吸的日最高值均出现在6:00,最低值分别出现在14:00、8:00和12:00,杂花苜蓿(M.varia)草地土壤呼吸速率最大值出现在8:00,最低值出现在14:00;4个苜蓿品种草地土壤呼吸速率值总体变化趋势是肇东苜蓿黄花苜蓿、杂花苜蓿龙牧801;土壤呼吸与植株根系、土壤温度呈线性正相关,与大气温度呈一元二次函数正相关,与土壤含水量呈负相关。  相似文献   

10.
不同放牧制度下短花针茅荒漠草原土壤呼吸动态研究   总被引：6，自引：2，他引：4  
采用动态密闭气室法(IRGA),对短花针茅荒漠草原土壤呼吸进行野外定位观测,分析了生长季不同放牧制度土壤呼吸速率的日变化、季节变化及其与环境因子的关系。结果表明,1)不同放牧制度下短花针茅荒漠草原土壤呼吸日、季节动态差异不大,日动态受温度影响呈单峰曲线,季节变化主要受到水分因子的影响;2)与自由放牧土壤呼吸日均速率(0.449 7 μmol CO2/m2·s)相比,划区轮牧(0.504 7 μmol CO2/m2·s)在干旱月份较大,围栏禁牧(0.529 5 μmol CO2/m2·s)除生长季初都显著增大,但纵观整个生长季,不同放牧制度下土壤呼吸均值差异不显著;3)土壤呼吸日均速率与气温的相关性大于与土壤温度的相关性,水温复合模型较单因子模型更好地解释土壤呼吸速率的变化;4)划区轮牧和自由放牧较围栏禁牧增大了土壤呼吸的温度敏感性(水分充足时),降低了土壤水分对土壤呼吸的影响。研究表明,不同的放牧方式对土壤呼吸速率及其环境因子效应影响较小,围栏禁牧较自由放牧改变了土壤呼吸日均速率及水热因子效应。  相似文献   

11.
试验选用96头平均体重14.82 kg左右的杜×长×大断奶仔猪,随机分成4组,每组3栏,每栏8头(公母各半)。对照组饲喂基础日粮,试验1、2、3组分别添加1%80目白术、0.2%白术多糖和1%微米白术。试验期30 d。结果表明:在生长性能方面,与对照组相比,1%微米白术添加组可显著提高日增重(P0.05)、降低饲料增重比和腹泻率,而且效果优于1%80目白术组和0.2%白术多糖组,在肠道形态和肠道微生态区系方面,与对照组相比,日粮添加1%80目白术、0.2%白术多糖、1%微米白术均可不同程度的提高十二指肠和空肠的绒毛高度,加深十二指肠和空肠的隐窝深度,并且增加肠道微生态区系的多样性,其中以1%微米白术添加组的效果最佳。  相似文献   

12.
Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.  相似文献   

13.
Tropical Animal Health and Production -  相似文献   

14.
1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.  相似文献   

15.
Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.  相似文献   

16.
Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.  相似文献   

17.
Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.  相似文献   

18.
Genetic variations in chromosome Y are enabling researchers to identify paternal lineages, which are informative for introgressions and migrations. In this study, the male‐specific region markers, sex‐determining region‐Y (SRY), amelogenin (AMELY) and zinc finger (ZFY) were analysed in seven Turkish native goat breeds, Angora, Kilis, Hair, Honaml?, Norduz, Gürcü and Abaza. A SNP in the ZFY gene defined a new haplotype Y2C. All domestic haplogroups originate from Capra aegagrus, while the finding of Y1A, Y1B, Y2A and Y2C in 32, 4, 126 and 2 Turkish domestic goats, respectively, appears to indicate a predomestic origin of the major haplotypes. The occurrence of four haplotypes in the Hair goat and, in contrast, a frequency of 96% of Y1A in the Kilis breed illustrate that Y‐chromosomal variants have a more breed‐dependent distribution than mitochondrial or autosomal DNA. This probably reflects male founder effects, but a role in adaptation cannot be excluded.  相似文献   

19.
The objective of this report was to characterize 20-year changes in proportion of calcium oxalate (CaOx) calculi and struvite calculi in dogs, and associations with breed, age, and sex. In this retrospective study, results of analysis of urinary calculi from dogs were reviewed for specimens received between July 1, 1981, and December 31, 2001. Breed, sex, age, year of submission of the specimen, and mineral type(s) were analyzed statistically. CaOx or Struvite or both were contained in 18,966 of 20,884 (91%) specimens. For both sexes, a 20-year statistically significant increase was observed in the proportion of calculus specimens that contained CaOx. The increase in this proportion was greater in females (1% to 31%) than in males (18% to 82%). From 1998 to 2001, when proportions may have plateaued, the odds of specimens containing CaOx were markedly higher in 18 breeds, markedly lower in 5 breeds, and not significantly different in 13 breeds compared with crossbreds. For both sexes, a 20-year statistically significant decrease was observed in the proportion of calculus specimens that contained struvite. This decrease in proportion was greater for males (79-16%) than for females (97-68%). From 1998 to 2001, when proportions plateaued, the odds of calculi containing struvite were markedly lower in 20 breeds, markedly higher in 1 breed, and not significantly different in 15 breeds when compared with crossbreds. Breed, age, and sex were associated statistically with CaOx or struvite urolithiasis. In conclusion, there appears to have been a long-term increase in the proportion of specimens of canine urinary calculi that contain CaOx as well as a long-term decrease in the proportion of specimens of calculi that contain struvite for both male and female dogs. The rate of change appeared to begin leveling off in the period 1998 to 2001. The recent proportion of dogs with either CaOx- or struvite-associated urolithiasis may depend on breed, age, and sex, and on interactions among these 3 factors.  相似文献   

20.
<正>1.INTRODUCTION Ensuring transportation network security is one Of the most daunting challenges confronting homeland security agencies today.Significant research has been dedicated.To model and analyze the vulnerability of transportation systems,while notably fewer studies propose specific strategies for deploying defensive technologies to safeguard these systems.  相似文献   

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