共查询到20条相似文献，搜索用时 609 毫秒
1.
采用堵洞法设置高原鼠兔干扰区和非干扰区,然后在干扰区和非干扰区内利用样方法研究了高原鼠兔干扰对青海湖流域高山嵩草草甸植物多样性和地上生物量的影响。结果表明,植物物种多样性和不同植物功能群多样性对高原鼠兔干扰的响应并不一致,其中干扰增加了杂类草功能群丰富度指数与物种丰富度指数,降低了物种均匀度指数、莎草科功能群丰富度指数和禾草科功能群均匀度指数(P<0.05)。干扰区内物种均匀度指数、物种丰富度指数和杂类草功能群丰富度指数随干扰强度增加而呈增加趋势,但禾草科功能群均匀度指数却呈显著降低趋势。虽然高原鼠兔干扰显著降低了植物群落总生物量,莎草科、禾草科和豆科功能群生物量(P<0.05),但显著增加了杂类草功能群生物量(P<0.05)。干扰区随干扰程度增加,莎草科功能群和豆科功能群生物量逐渐降低,杂类草功能群生物量逐渐增加,而禾草科功能群生物量则先增加后降低。鉴于高山嵩草草甸植物群落物种多样性和功能多样性对高原鼠兔干扰的响应不一致,植物物种多样性和功能群多样性之间不能互相替代。 相似文献
2.
为了研究刈割干扰下天然打草场植物群落呈现出的消长状态,试验对呼伦贝尔草甸草原天然打草场不同植物群落物种组成、数量特征、物种多样性、生物量等指标进行了定量分析。结果表明:在刈割干扰下,羊草+杂草类群落中物种总数略低于贝加尔针茅+羊草群落;羊草+杂类草群落的密度和盖度均显著高于贝加尔针茅+羊草群落(P0.05);羊草+杂类草群落的Shannon-Wiener多样性指数和Pielou均匀度指数均显著高于贝加尔针茅+羊草群落(P0.05);羊草+杂类草群落的现存量和枯落物量均显著高于贝加尔针茅+羊草群落(P0.05)。说明刈割干扰对羊草+杂类草群落的影响小于对贝加尔针茅+羊草群落的影响。 相似文献
3.
放牧对草地植物群落结构和功能的影响深远而复杂,为了探讨高寒草甸植物物种多样性和生产力受长期不同放牧强度的影响,在高寒草甸草地群落设置不同放牧强度试验,分析不同放牧强度下植物群落物种多样性和生产力及其关系的变化,以期为高寒草甸生态系统的可持续利用和管理提供理论依据。结果表明,随着放牧强度的增大,草地植物群落的Shannon-Wiener指数和Margalef丰富度指数先增大后减小,高寒草甸植物群落的优势物种由禾本科向莎草科和杂类草转变,其中禾本科植物的优势度从70%降到12%,杂类草植物的优势度由13%增大到82%,植物群落的地上净初级生产力(ANPP)逐渐减小,轻度放牧处理减少了61.56%,中度放牧处理减少了76.75%,重度放牧处理减少了78.72%,重度放牧处理地下净初级生产力(BNPP)比禁牧处理降低了90.06%,轻度放牧、中度放牧处理地下净初级生产力与禁牧处理无明显差异,3个处理下的地下净初级生产力(NPP)总体保持稳定。放牧强度增大会导致植物群落高度下降,中度放牧处理会增加植物群落中莎草科植物的分蘖数。高寒草甸上植物群落的Pielou指数和NPP负相关,Margalef指... 相似文献
4.
在鲁中南低山丘陵地区选取典型灌草丛样地,以草地植被为研究对象,在一年刈割2次条件下设置5个刈割强度,分别以不同留茬高度来表示,即不刈割(CK)、留茬20 cm(D)、留茬15 cm(C)、留茬10 cm(B)和留茬5 cm(A),研究刈割对灌草丛草地植被物种多样性和生产力的影响,以期为本地区灌草丛草地生态保护与可持续利用提供理论依据和技术支撑。经过连续2年试验,结果表明:刈割不同程度上降低了野古草(Arundinella anomala)、荩草(Arthraxon hispidus)、野菊(Dendranthema indicum)主要优势植物重要值,留茬15 cm和20 cm处理下,结缕草(Zoysia japonica)重要值高于对照;刈割促使草地植被物种多样性增加。随着留茬高度的降低,Margalef指数、Simpson指数和Shannon-Wiener指数变化趋势一致,先增加后减少,以留茬15 cm处理最大,Pielou指数则呈现一直增加的趋势;不刈割处理草地植被产量最高,随着留茬高度的降低,草地植被产量降低;草地植被物种多样性与生产力呈单峰格局关系,一定程度的刈割可增加草地植被物种多样性。从草地植被产量和植被物种多样性来看,本区域灌草丛草地植被生态系统还较为脆弱,在利用的同时应更注重投入和恢复,促使草地系统健康稳定发展。 相似文献
5.
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
6.
蚂蚁类属土壤节肢动物，是草地生态系统中不可忽视的组成因子。以青藏高原高寒草甸植物群落为对象，在青海省门源县设置小蚁丘(S)、中蚁丘(M)、大蚁丘(B)和废弃蚁丘(A)4个处理，探讨了不同面积蚁丘对草地植物群落多样性的影响。结果表明：青藏高原高寒草甸区蚁丘随机分布，随蚁丘面积增大，草地植物群落丰富度和多样性指数降低，而优势度和均匀度指数无显著变化。沿着小蚁丘(S)、中蚁丘(M)、大蚁丘(B)的环境梯度，禾草科功能群多样性先升高后降低，莎草科先降低后升高，豆科类和杂类草功能群多样性持续降低。因此，青藏高原高寒草甸区，随蚁丘面积的增加改变了禾草科、莎草科、豆科类和杂类草等功能群多样性；但废弃蚁丘上群落多样性具备自我恢复能力，与天然群落无显著差异。 相似文献
7.
不同刈割强度下羊草草甸草原生物量与植物群落多样性研究 总被引：7，自引：1，他引：6
以内蒙古高原南缘羊草草甸草原为对象,设5个利用梯度,即不刈割、留茬2,5,10和15cm,研究了连续刈割处理3年后羊草草甸草原生物多样性与地上生物量的变化规律。结果表明,群落中羊草地上生物量随刈割强度的增大而减小(P<0.05);群落生长量为不刈割处理显著高于留茬10和15cm(P<0.05);多样性指数(Margalef、Simpson、Shannon-Wiener和Pielou指数)随刈割强度的增大而增大(P<0.05)。羊草相对密度随刈割强度的增大而减小,糙隐子草和委陵菜属植物随刈割强度增大而增大(P<0.05)。相关分析表明群落多样性指数与地上生物量之间呈“单峰型”曲线关系,而与草原优势物种——羊草的地上生物量呈显著负相关关系(P<0.05)。 相似文献
8.
通过对大武地区小嵩草草甸的研究,分析了不同程度退化草地群落结构和地上、地下植物量的变化。结果表明:随着退化程度的加重,群落的组成和优势种发生了很大的变化,植物群落从以莎草科为主,向以杂类草为主的群落演替;地上、地下植物量均呈现下降趋势,而杂类草的地上生物量则表现出逐渐增加的趋势。几种不同程度退化草地的地下植物量主要分布在0~10cm的范围内,且显著高于其它层;物种多样性、均匀度指数有下降趋势。 相似文献
9.
不同管理对山地草甸植物空间分布及生物量的影响 总被引：3，自引：0，他引：3
研究不同管理措施对山地草甸类自然保护区植物地上和地下生物量变化及其空间分布的规律。结果表明,7月中下旬生物量最高,但各经济类群出现的时间不同。地下生物总量远远超过地上部,其中杂类草、禾草和莎草的根量大于地上生物量,而豆科和菊科植物则相反。缓冲区的杂类草最多,而核心区和实验区的禾草和莎草最多。核心区地上枯死物总量与地上部接近。实验区地上及地下枯死物较少。不同管理措施对株高的影响较大,而对根长的影响不显著。同一植物在不同分区,株高和根长各异,其变化不成正相关。 相似文献
10.
11.
Air hygiene in a broiler house: comparison of deep litter with raised netting floors 总被引：2，自引：0，他引：2
1. Deep litter and raised netting flooring systems in broiler houses were compared for their effects on air quality and bird health during an 8-week growing period. 2. Weekly measurements were taken of respirable dust, numbers of airborne microorganisms and concentrations of gaseous pollutants. Airborne fungi and bacteria were identified to species. 3. At the end of the experimental period, randomly sampled bird lungs were examined for the presence of viable microorganisms and for pathological changes. Bird health and performance were monitored throughout the 8 weeks. 4. Respirable dust concentrations and numbers of airborne microorganisms were significantly higher in the litter rooms. The type of floor had no effect on concentrations of gaseous ammonia. 5. Floor type had no significant effect on bird mortality but birds on litter had a slightly better gain:food ratio. However, birds on litter were observed to have a higher incidence of lung damage and more of the birds on litter had viable microorganisms present in the lungs at necropsy. 相似文献
12.
In continuation of our earlier investigations on the range of environmental factors in housing systems with perforated floors and the experiments with or without free choice on litter or deep litter the effects of the size of the area and the environmental temperatures on the behaviour of early weaned piglets (8 kg to 30 kg) kept on litter and deep litter have been investigated. Both factors had a crucial but diametrical influence. While for the total activity of the pigs the size of the compartment proved more important than room temperature, for the total inactivity it was the other way around. Therefore some essential requirements have to be obeyed even for housing systems with litter or deep litter, which can be considered more suitable for the housing of pigs from the start on. Because of their different importance for the activity (20% of the total behaviour) and the inactivity (80%) the factors can't replace each other. For housing systems with litter size allocation shouldn't amount less than 0.45 m2/animal and with deep litter not less than 0.70 m2/animal with room temperatures starting at about 25 degrees C and 20 degrees C, respectively. 相似文献
13.
小梅山猪促卵泡素β基因多态性及其与繁殖性能的关系 总被引：16，自引：0，他引：16
用PCR SSCPs法检测小梅山猪母猪群促卵泡素 (FSH) β基因的多态性 ,分析该基因与产仔数和仔猪体重的关系。小梅山猪母猪群FSH β基因N基因频率为 0 .4 14 1,n基因频率为 0 .5 85 9,该基因处于遗传非平衡状态。nn基因型母猪的总产仔数和产活仔数比NN型母猪的分别多 0 .7头和 1.1头 (P <0 .0 5 )。小梅山猪产仔数曲线是开口向下的二次曲线 ,其中nn型母猪具有较理想的产仔模型 ,其拟合的最高产仔数最大 ,且产仔数达高峰后下降较慢。nn型母猪的仔猪初生重比NN基因型母猪的重 (P <0 .0 5 )。杂合型母猪的总产仔数 (12 .38)、产活仔数 (11.6 9)、仔猪初生重 (1.72 )和 35日龄断奶重 (2 0 .16 )比纯合型母猪的大 ,表现出一定的杂合效应。这些结果提示母猪的n等位基因对产仔数和仔猪初生重有利 ,该基因可望用于猪的标记辅助选择 相似文献
14.
Two experiments were conducted to investigate the differences in susceptibility to foot pad dermatitis (FPD) of two medium-heavy lines of turkeys, and whether FPD is painful, by detailed analysis of behaviour in birds with and without analgesic treatment (betamethasone).
Turkeys housed on dry litter in the first experiment generally had more frequent bouts of different behaviours that were of shorter duration than birds on wet litter. T-patterns (behavioural sequences) were more frequent, varied and complex on dry than on wet litter. Betamethasone-injected birds of line B, but not breed A, had shorter resting and longer standing durations on wet litter than saline-injected birds.
In the second experiment, turkeys on wet litter given saline stood less and rested more than all other treatment groups, suggesting that they experienced pain that was alleviated in birds receiving betamethasone. Turkeys on dry litter had more frequent, varied and complex patterns of behaviour than turkeys on wet litter and birds kept on intermediate litter wetness. Betamethasone provision increased pattern variety regardless of litter treatment.
Turkeys with low FPD scores transferred to wet litter and given saline injections had a longer total duration of resting and shorter duration of standing compared to betamethasone-treated birds. Low FPD birds transferred to wet litter had a similar number of patterns and total pattern occurrence as high FPD birds transferred to dry litter. Betamethasone increased pattern variety and frequency compared to saline injections whereas overall pattern complexity was similar.
It was concluded that wet litter affects the behaviour of turkey poults independently of FPD and that betamethasone may also change the behaviour of turkeys. There was some evidence from analgesic treatment and T-pattern analyses that FPD was painful. However, there was no evidence of differences in susceptibility to FPD of the two commercial hybrids.
15.
Reproduction in Javanese sheep: evidence for a gene with large effect on ovulation rate and litter size 总被引：2，自引：0，他引：2
G E Bradford J F Quirke P Sitorus I Inounu B Tiesnamurti F L Bell I C Fletcher D T Torell 《Journal of animal science》1986,63(2):418-431
Three breeds of Javanese sheep are described briefly and data suggesting the segregation of a gene with large effect on ovulation rate and litter size are presented. The three breeds are Javanese Thin Tail (JTT), Javanese Fat Tail (JFT) and Semarang (SEM), the last possibly a substrain of JTT. All three breeds have mean mature ewe weights under 30 kg. Ovulation rate and litter size did not differ significantly among the three; all had litter sizes of up to 4 or 5 with a mean for mature ewes of approximately 2. Ovulation rate ranged from 1 to 5 and had an average within-breed repeatability of .8 within season and .65 between seasons. Within-breed repeatability of litter size was .35 +/- .06. Prenatal survival in pregnant ewes with two, three and four or more ovulations averaged 93, 88 and 86% over two seasons. Dams that had at least one ovulation rate or litter size record greater than or equal to 3 produced two groups of daughters in approximately equal numbers: one group with many records greater than or equal to 3 and mean ovulation rate and litter size of 2.73 and 2.31, respectively, and one group with ovulation rates and litter sizes of 1 or 2 and corresponding means of 1.39 and 1.38. Dams with ovulation rate or litter size records of only 1 or 2 produced daughters in which over 90% had records of only 1 or 2. Estimated heritabilities for the mean of approximately three ovulation rate or litter size records from these daughter-dam comparisons exceeded .7. These results suggest segregation of a Booroola-type gene, one copy of which increases ovulation rate by about 1.3 and litter size by .9 to 1.0. Relationships between duration of estrus and ovulation rate, and between timing of release of luteinizing hormone and number of eggs shed, resemble the pattern in Booroola Merino more closely than that in Finnish Landrace or Romanov, supporting the hypothesis of a major gene. 相似文献
16.
为完善猪发酵床养殖技术及促进土壤对垫料中磷的利用,研究分析同等时间干法发酵床和湿法发酵床表层垫料、中层垫料和底层垫料中磷的变化情况。结果表明：（1）湿法发酵床垫料水分含量、温度极显著高于干法发酵床（35.54%＆31.49%、34.87℃＆31.91℃）,垫料深度对水分含量、pH、温度有极显著影响（P〈0.01）,垫料中层温度最高;（2）湿法发酵床和干法发酵床总磷含量无差异（3.00%＆3.43%）;植酸磷极显著低于干法发酵床（21.04mg/kg＆27.59mg/kg）,有效磷极显著高于干法发酵床（94.22mg/kg＆91.16mg/kg）,垫料深度对总磷、植酸磷、有效磷有极显著影响（P〈0.01）;（3）湿法发酵床植酸酶、中性磷酸酶、脲酶活性高于干法发酵床（2.98U/L＆2.56U/L、25.83mg/g＆21.77mg/g、1.93U/L＆1.88U/L）,垫料深度对该三种酶活性有极显著影响（P〈0.01）;垫料中层总磷、植酸磷、有效磷含量及该三种酶活性最高。发酵床种类和垫料深度对垫料pH、植酸磷、植酸酶活性的互作极显著（P〈0.01）。研究表明,发酵床中磷的降解主要发生在垫料中层,湿法发酵床更有利于垫料中磷的降解,干法发酵床在养殖过程中需增加垫料的湿度。 相似文献
17.
The pregnancy rate and the subsequent litter size were studied in 332 Swedish Yorkshire primiparous sows, fed according to a commercial Swedish feeding regime during lactation. The sows were weighed and backfat depth was recorded at the first farrowing, at weaning, and at mating. Oestrous detection was performed once daily after weaning, and the interval from weaning to first oestrus (IWO) was recorded. Blood samples for determination of plasma progesterone were drawn regularly after the first weaning. Statistical analyses were only performed on sows with an IWO of 3-8 days. Of these 206 sows were mated on their first (OE1 sows) and 87 sows on their second (87 OE2 sows) oestrus after weaning.The pregnancy rate was 85.4% for OE1 sows and 75.9% for OE2 sows (p=0.048). There was no significant difference in pregnancy rate between OE1 sows with an IWO of 3-5 days and OE1 sows with an interval of 6-8 days. OE2 sows with an IWO of 6-8 days, on the other hand, had a significantly lower pregnancy rate compared with OE2 sows with an interval of 3-5 days. The pregnancy rate in sows that lost more than 30 kg during the first lactation period did not differ from that of sows losing less than 30 kg. In sows with a first litter size of more than 9 piglets alive at birth, the pregnancy rate decreases significantly if mating is delayed until the second oestrus after weaning.OE2 sows had a significantly larger second litter size at birth than OE1 sows (+ 2.0). The litter size at six weeks did not, on the other hand, differ significantly (+ 0.4). There was a positive correlation between the IWO and 2nd litter size, although significant only for OE1 sows between the IWO and litter size alive at birth. In the OE1 group, sows losing 20 kg or less during lactation had significantly larger second litters at birth than the sows losing 21-30 kg, but not significantly larger than the sows losing more than 30 kg. One piglet more, at birth, in the first litter resulted in 0.25 piglet more in the second litter. For sows with a large first litter there was a low probability of also having a large second litter. 相似文献
18.
东北羊草草原枯草层对植物群落的作用 总被引：4，自引：0，他引：4
通过对东北典型羊草群落枯草层的调查和观测，结果表明，枯草层对羊草早春的返青有一定影响。适宜的枯草层促使羊草提前返青，生长加快，而过厚和缺少时则使返青延迟。群落的物种数随着枯草层厚度的增加而增加，枯草层800g／m2达到峰值后有所下降，枯草层厚度的处理梯度越接近，样地间的物种相似性系数也越接近，反之相似性系数差异越大，群落的各种数量特征，如密度、高度、盖度、频度和地上生物量随着枯草层厚度的增加而增加，达到峰值后则逐步减少。羊草地上生物量占地上生物总量的比例随着枯草层的增厚而呈递减趋势。 相似文献
19.
Sixteen third-parity sows maintained under two photoperiod treatments (16 h light: 8 h dark [16 h] or 4 h light: 20 h dark [4 h]) were assigned to be unilaterally ovariectomized (left ovary) at weaning on d 28 after farrowing a small litter (12 or fewer piglets; S) or a large litter (more than 12 piglets; L). Antral follicles were classified as atretic or nonatretic and divided into six size classes. The right ovary was obtained at slaughter, 16 d after estrus was detected. Number of antral follicles in the left ovary was greater (P less than .05) for L sows (540) than for S sows (427). Sows exposed to 16 h of light with large litters had a higher number of atretic follicles than all other groups (litter size x photoperiod interaction, P less than .05). Number of nonatretic follicles were similar between groups. However, when nonatretic follicles were classed by size (1 = smallest; 6 = largest), their distribution differed. In Class 1, L sows had more follicles than S sows (P less than .05). For Classes 3 and 4, photoperiod interacted with litter size to decrease the number of follicles in L 16 h sows (litter size x photoperiod interaction, P less than .05). These lower numbers of nonatretic follicles were related to a higher rate of follicular atresia in L 16 h sows. In Classes 2, 3 and 4, L 16 h sows had more atretic follicles than any other group (litter size x photoperiod interaction, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
20.
为优化母猪繁殖效率,探究妊娠期不同背膘厚对母猪繁殖性能和分娩产程的影响,本研究以广西某公司2 969头大白母猪和1 787头长白母猪为试验群体,收集2017年1月至2017年10月妊娠期3个阶段(妊娠30、80和107 d)背膘厚与分娩接产记录数据,分析背膘厚与分娩产程、总产仔数、产活仔数和初生窝重等性状的关系。研究结果表明,大白母猪分娩产程时间显著短于长白母猪(P<0.05),大白母猪总产仔数、产活仔数和初生窝重显著优于长白母猪(P<0.05)。在妊娠30 d时,背膘厚在18～20 mm组的大白母猪总产仔数和产活仔数最高,且初生窝重最大;背膘厚在18～20 mm组的长白母猪总产仔数和产活仔数最高。在妊娠80 d时,背膘厚≥20 mm组的大白母猪总产仔数和产活仔数最高,且初生窝重最大、产程最短;背膘厚在16～18 mm组的长白母猪总产仔数和产活仔数最高,且初生窝重较高、母猪产程较短。在妊娠107 d时,背膘厚在14～16 mm组的大白母猪总产仔数和产活仔数最高,且初生窝重最大,但母猪产程与其他组差异不显著(P>0.05);背膘厚≥20 mm组的长白母猪总产仔数和产活仔数最高,且初生窝重较大。妊娠期背膘厚减少1～2 mm的大白母猪,其总产仔数和产活仔数最高,初生窝重较小,产程较长。而背膘厚减少>2 mm的长白母猪,其总产仔数和产活仔数最高,初生窝重较大,产程较短。上述试验结果说明,在母猪妊娠期间,合适的背膘厚可有效提高母猪繁殖性能和母猪分娩期间的福利水平。养殖场可以根据营养配方和猪群品种建立背膘数据库,通过精准饲喂将母猪背膘厚调整至最佳范围,同时合理控制妊娠期背膘变化。 相似文献