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对大口黑鲈北方亚种(N)、佛罗里达亚种(F)及其正交子代(N♀×F♂)和反交子代(F♀×N♂)幼鱼的耐低温限度、耗氧率和窒息点进行了测定。结果表明:在驯化温度为20 ℃,降温速率为2 h/℃时,北方亚种的半致死低温最低为(3.10±0.17) ℃,佛罗里达亚种最高,为(5.05±0.21) ℃,正、反交子代介于两亲代群体之间,分别为(4.80±0.06) ℃和(4.20±0.17) ℃,对4种鱼的半致死低温进行单因素方差分析,显示4种大口黑鲈的半致死低温具有显著性差异(P<0.05)。采用封闭式流水装置测定大口黑鲈北方亚种、佛罗里达亚种及正反交子代的昼夜平均耗氧率分别为0.136 8 mg/(g·h)、0.1811mg/(g·h)、0.168 1mg/(g·h)和0.138 8 mg/(g·h),4个群体的昼夜平均耗氧率差异不明显。窒息点测定显示佛罗里达亚种的窒息点最高为0.4 mg/L,北方亚种的最低为0.33 mg/L,4个群体在窒息点上差异不显著(P>0.05) 相似文献
84.
ABSTRACT As more forest entities worldwide consider pursuing Forest Stewardship Council (FSC) certification, a critical question remains on whether stand-level management impacts differ between certified and uncertified forests. To begin to answer this question, we measured forest structure on three FSC-certified stands, three uncertified stands, and six adjacent unharvested reference stands (12 stands total) composed primarily of sugar maple (Acer saccharum) on non-industrial private properties in central Vermont, USA. The certified and uncertified partial harvests reduced total tree biomass and live tree carbon storage by one-third compared to reconstructed pre-harvest conditions. Both treatments also contained significantly lower densities of saplings and some mid-size trees compared to non-harvested references due to similar impacts from harvesting. The net present value of merchantable sugar maple over 10 year projections was consistently lower on certified than uncertified stands, but this difference was insignificant at discount rates from 4–8%. The certified stands contained significantly greater total residual volumes of coarse woody debris (standing and downed) than uncertified stands, although the debris was smaller than that found in unmanaged mature forests. Overall, our data suggest that FSC-certified harvested stands in northern hardwood forests have similar sugar maple timber value, aboveground live tree carbon storage value, similar live tree structure, and greater residual coarse woody debris than uncertified harvested stands. 相似文献
85.
针对承德稻区水稻育秧过程中出现了一系列突出问题,承德市农业技术推广站对该地区育秧技术进行试验探索,集成了"水稻双无育秧法",结果表明,双无育秧法秧苗期温湿度容易控制,基本保持在20℃左右,适合秧苗生长;基质透气、透水性强,不携带各类病菌,避免了土传病菌的侵害;水稻秧苗根系发达,根须比常规育秧多一倍,根粗、根壮,比常规育苗根长2~3 cm;水稻苗期立枯、青枯、黄化病没有发生,秧苗株型合理、根系发达、带孽率高、插秧后缓苗快;比常规育秧增产3%~4%,效果显著。 相似文献
86.
随着人们对野生动物保护工作意识的加强及对野生动物人工驯养繁殖经济价值的重
视,本文以西丰县为试点,针对辽北地区人工养殖繁育梅花鹿情况进行系统调研,总结出梅花鹿
冬季饲养管理技术,以促进人工养殖繁育梅花鹿产业的稳定、持续发展。 相似文献
87.
在比长柄扁桃种源地更加寒冷、干旱的晋北半干旱风沙区开展长柄扁桃引种试验,结果表明,造林成活率在不浇水条件下达到91. 67%,苗木根系发育良好,新梢生长旺盛,实现了育苗技术本土化。长柄扁桃表现出优良的抗逆性,能够适应晋北半干旱风沙区的气候。 相似文献
88.
Cameron A. Duquette Craig A. Davis Samuel D. Fuhlendorf R. Dwayne Elmore 《Strength and Conditioning Journal》2019,72(3):484-491
Despite the fact that the northern bobwhite (Colinus virginianus Linnaeus; hereafter, bobwhite) is one of the most well-studied and widely distributed wildlife species in North America, we know little about how bobwhite respond to oil and gas infrastructure. We investigated the impacts of oil and gas development on space use of bobwhite using a multiseason approach. We captured and monitored bobwhite in the breeding season (1 April–30 September, n = 135 individuals) and nonbreeding season (1 October–31 March, n = 30 coveys) and modeled their habitat selection in a resource-utilization function (third order, within home range selection) and resource-selection function (second order, home range selection) format. Generally, energy infrastructure effects on bobwhite were neutral, but breeding season bobwhite did select for areas near low-traffic roads (β = ? 0.31 ± 0.15 SE). In the nonbreeding season, coveys selected for areas within their home range with a limited viewshed (i.e., areas with limited visibility of anthropogenic structures; β = ? 0.03 ± 0.02 SE). Selection differed between sexes for well pads (t = ? 2.12, P = 0.04) but was otherwise similar. At the level of home range selection, bobwhite exhibited a preference for areas with a low density of oil and gas wells and a high density of low-traffic roads during both the breeding and nonbreeding seasons (breeding: βwell = ? 0.14 ± 0.02, βroad = 0.26 ± 0.27; nonbreeding: βwell = ? 0.08 ± 0.03, βroad = 0.16 ± 0.03). As a generalist species, bobwhite appear to be largely tolerant of energy infrastructure and associated disturbances at moderate levels of development but may be sensitive to high densities of oil and gas pads. 相似文献
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90.
2014年7月至2015年5月采集南海北部陆架海域的多齿蛇鲻(Sauridatumbil)和花斑蛇鲻(Sauridaundosquamis)样本,测量其叉长、体重、性腺成熟度,并读取其耳石和日龄数据,对这2个种的生物学特征进行比较,发现多齿蛇鲻和花斑蛇鲻叉长、体重雌雄间差异显著(P0.05)。多齿蛇鲻雌性与雄性样本,叉长范围分别为109~310 mm、117~283 mm,体重范围分别为13~358 g、20~297 g,日龄范围分别为76~558 d、73~526 d, von Bertalanffy生长方程的相关参数分别为:L_(∞♀)=278 mm, L_(∞♂)=276 mm; K_♀=1.30, K_♂=1.30; t_(0♀)=-0.07 a, t_(0♂)=-0.08 a。雌性性腺成熟度Ⅲ期样本从350~400 d日龄组开始出现,雌性与雄性样本孵化高峰期在3月、7月、9—10月。花斑蛇鲻雌性与雄性样本,叉长范围分别为105~269 mm、95~264 mm,体重范围分别为11~220 g、8~228 g,日龄范围分别为79~486 d、84~488 d, von Bertalanffy生长方程的相关参数分别为:L_(∞♀)=269 mm, L_(∞♂)=265 mm, K_♀=1.29, K_♂=1.29, t_(0♀)=-0.06 a, t_(0♂)=-0.06 a,雌性性腺成熟度Ⅲ期样本从200~250 d日龄组开始出现,雌性与雄性样本孵化高峰期在6—11月。与历史资料进行对比,发现南海海域多齿蛇鲻与花斑蛇鲻出现个体大小逐渐减小、性成熟提前等适应性特征。结论认为,为了南海多齿蛇鲻与花斑蛇鲻渔业资源的可持续发展,需要降低南海近海的捕捞压力以促进南海渔业资源的发展。 相似文献