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江河源头不同程度退化小嵩草高寒草甸草场的封育效果 总被引：7，自引：2，他引：5
通过对位于江河源头达日县的不同退化程度小嵩草Kobrecia parva高寒草甸3年的封育研究,结果表明:围栏封育对不同退化程度小嵩草高寒苹甸草场的总盖度及不同经济类群植物的益度、总地上生物量、不同经济类群植物的地上生物量及其组成、退化群落对未退化群落(原生植被)的相似性系数均有显著的影响。经过3年的封育后,草地植被总盖度、总地上生物量、禾本科和莎草科植物的盖度和地上生物量、群落的相似性系数均有不同程度的增加。轻度退化草地封育2-3午后,草地的优良牧草及可食杂类草不论是盖度还是地上生物量均高且占绝对优势,草地即可得到恢复;中度退化草地要靠封育恢复需要的时间可能会更长一些;重度和极度(黑土滩)退化草地,必须通过建植人工草地、结合补播、施肥、毒杂草防除等其它措施改良,以治本的工程措施为主。 相似文献
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为研究补播对高寒草地群落特征和植被多样性的影响,本研究以黑土滩中度退化草地为对象,利用免耕补播机通过近自然补播措施进行了恢复,测定了恢复后草地的群落组成及多样性特征。结果表明：经人工补播后,退化草地的植被盖度,地上、地下生物量,禾本科牧草比例和根冠比都显著上升（P<0.05）,补播措施起到了很好的修复效果。从物种组成上看,退化草地经过补播之后,其植被群落组成和物种重要值都发生了变化。其中,禾本科牧草和莎草科牧草占据了重要地位。此外,物种丰富度指数、Shannon-Weiner指数、均匀度指数经人工补播后都有所上升,但差异不显著。综上所述,人工补播是高寒地区黑土滩中度退化草地修复一种快速有效的措施,能够有效的提高可食牧草的比例,同时也有利于高寒地区草地植被恢复。 相似文献
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对三江源区不同退化程度高寒草甸草地植物群落、生物量及土壤养分差异进行了研究,结果表明:随着退化程度的加重,高寒草甸草地的群落组成发生了很大的变化,以莎草科植物为主的植物群落向阔叶型杂类草群落演替;物种多样性、均匀度指数均有下降趋势;地上、地下生物量,土壤养分均呈现明显下降趋势. 相似文献
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补播对高寒草甸生产力和植物多样性的影响 总被引：5，自引：0，他引：5
为了解补播对高寒草甸退化草地恢复过程中群落生产力、功能群结构和物种多样性方面的影响,于2010年5月以位于青藏高原东段的玛曲高寒草甸为研究对象,进行了补播试验。结果表明,补播显著提高地上生物量,同时物种数和丰富度指数Margalef也有显著增加,其中补播处理地上生物量是不补播处理的1.31～1.44倍。补播后莎草类和禾草类地上生物量都呈增长趋势,补播后禾草类地上生物量显著提高,其中最高是不补播的2.7倍,杂类草在群落中所占比例显著降低。适量补播既可以使草地的经济价值得以提高,同时也有利于高寒退化草地的恢复和生态系统的稳定。 相似文献
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通过对高寒草甸天然草地实施划破、补播、施肥及综合处理,探讨了不同草地植被恢复措施对高寒草甸有毒植物物种组成、多样性及生物量的影响。结果表明,不同处理草地中,有毒植物的组成及比例差异显著(P<0.05)。与对照相比,补播、划破和施肥均不同程度地降低了群落中有毒植物的物种数和Shannon Wiener指数(P<0.05),不同处理草地有毒植物物种数和Shannon Wiener指数排序分别为补播<施肥=综合处理<划破<对照,补播<划破<施肥<对照<综合处理。补播、施肥和综合处理均可有效降低群落中有毒植物的地上生物量(P<0.05),而草地划破在一定程度上增加了有毒植物的地上生物量(P>0.05),不同处理草地有毒植物地上生物量排序为补播<综合处理<施肥<对照<划破。补播形成的垂穗披碱草(Elymus nutans)单一优势群落使有毒植物物种数、物种多样性及地上生物量均下降到最低值,对于毒杂草型退化草地的改良,草地补播是可供参考的有效恢复措施之一。 相似文献
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改则高寒荒漠草地改良效果 总被引：3，自引：0，他引：3
对西藏阿里地区改则县高寒荒漠退化草地,采用了围栏、围栏＋灌溉及围栏＋灌溉＋补播3种改良措施,以围栏外天然草地为对照,通过研究几个改良措施对草地植物高度、盖度、密度、地上生物量、重要值及物种多样性的影响,寻求适宜于该类退化草地恢复的最佳措施。结果表明,3种改良措施与对照相比均能明显改善退化草地群落中所有植物的生长状况;围栏＋灌溉、围栏＋灌溉＋补播措施可以提高高寒荒漠退化草地的物种多样性;与其他改良措施相比,围栏＋灌溉＋补播措施可以显著提高高寒荒漠退化草地物种均匀度;综合考虑,围栏＋灌溉措施更适宜于改则县高寒荒漠退化草地的改良恢复。 相似文献
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《青海畜牧兽医杂志》2017,(2)
本试验以河南县高寒草甸草地类型为研究对象,研究不同补播年限下高寒草甸地上生物量、植物群落多样性与土壤养分特征的相关性。结果表明:高寒草甸补播禾本科植物可有效增加草地地上生物量,提高群落物种数和丰富度指数。同时也表明土壤水分成为本区域限制植物生长的主导因素,土壤全氮、全磷含量次之。研究结果可为高寒草甸退化草地科学改良及草地合理利用提供数据参考。 相似文献
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为探明多年生不同混播组合草地退化后的群落稳定性和可持续性,本研究以祁连山金强河地区22年前建植的6种混播草地为研究对象,对草地群落结构及地下芽库构成进行调查分析。结果表明：4组分混播草地能够较好的保留建植种的地下芽,且以建植种分蘖芽为主,而3组分混播草地地下芽主要由侵入种的分蘖芽、根茎芽、根颈芽和根蘖芽构成,建植种芽密度占比较低;分蘖芽密度与建植种植物盖度、密度和地上生物量正相关,根茎芽、根颈芽、根蘖芽密度与侵入种植物盖度、密度和地上生物量正相关。其中,混播组合“冷地早熟禾(Poa crymophila)+多叶老芒麦(Elymus sibiricus)+无芒雀麦(Bromus inermis)+扁穗冰草(Agropgyron cristatum)”草地地下芽结构最优,可适当延长混播草地使用年限,是适宜青藏高原高寒地区的混播草种组合。 相似文献
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适宜的牧草混播对于改善退化高寒草甸及高寒地区畜牧业现状具有重要的现实意义,但不同牧草混播条件下退化高寒草甸土壤养分及生物量变化特征尚不明确。为此,本研究以垂穗披碱草（Elymus nutans）、早熟禾（Poa pratensis）、呼伦贝尔苜蓿（Medicago falcata）为试验草种,在三江源区重度退化高寒草甸开展为期3年的混播试验,探讨不同牧草混播对退化高寒草甸土壤养分及生物量的影响。结果表明：不同牧草混播条件下,草甸土壤有机碳含量与全氮及不同形态氮素含量呈显著正相关（P<0.05）;草甸土壤养分含量发生显著变化（P<0.05）,EM（垂穗披碱草+呼伦贝尔苜蓿）混播的土壤养分状况最佳;草甸地上、地下生物量显著增加（P<0.05）,EM混播的效果最为显著（P<0.05）。综上,在重度退化高寒草甸恢复过程中,如采取人工草地建植手段,建议选择EM混播。 相似文献
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青藏高原高寒草甸退化严重影响了草地群落结构与生产力.为揭示草地退化对高寒草甸群落结构和生物量地上/地下分配的影响,采用随机区组设计,在青海省海北州选择3个小区,每个小区设置完整的未退化、轻度退化、中度退化和重度退化4个退化梯度,于2020年8月对样地进行群落调查,同时采集植物样品.结果表明,随着退化程度加剧:1)草地的盖度、高度和地上植物生物量均显著下降;2)地上生物量在不同功能群的分配发生显著变化,物种逐步从以禾草类为优势转变为以杂类草为优势的群落;3)地下生物量显著下降,深层土壤根系生物量占比增加.研究结果表明:随着退化加剧群落结构发生颠覆性变化,且地上和地下生物量同步出现严重衰退.因此,针对该区域退化草地的植被恢复应考虑草地物种组配以及地上和地下生物量同步恢复的相应措施. 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献
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Billinghurst RC Brama PA van Weeren PR Knowlton MS McIlwraith CW 《American journal of veterinary research》2004,65(2):143-150
OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis. 相似文献