Results 31 to 40 of about 706,112 (165)
Shuitu Baochi Xuebao, 2011 通过对荒漠草原4种典型植物群落(蒙古冰草群落、甘草群落、赖草群落、沙蒿群落)枯落物蓄积量的调查,结合室内持水试验,运用数理统计的方法分别得到4种典型植物群落枯落物的蓄积量、最大持水量、吸水速率等水文特征参数。结果表明:荒漠草原不同植物群落枯落物蓄积量在50.8～396.2g/m2,其蓄积量由大到小为蒙古冰草群落>甘草群落>赖草群落>沙蒿群落,与植物群落地上生物量变化是一致的;4种植物群落枯落物最大持水量存在一定差异,蒙古冰草群落、甘草群落、赖草群落、沙蒿群落枯落物最大持水量分别相当于0.934,0 ...
李学斌 +6 more
doaj
Estimating the total mortality of seabirds following a marine heat wave
Conservation Biology, EarlyView.Abstract Marine heat waves detrimentally affect a range of marine species, including seabirds, and are increasing in frequency and severity. When thousands of dead seabirds wash up on beaches, the public becomes concerned. However, the number of dead birds recorded on beaches is only a fraction of the total mortality; most birds perish at sea.
Jennifer L. Lavers +3 more
wiley +1 more source
, 2000 运用截线抽样法调查了在春季4月间鄱阳湖区长江江豚(Neophocaena phocaenoides asiaeorientalis)的种群密度和数量,得出该地区长江江豚种群密度估计值为0.1940头/km2 ,估计数量为388头 ...
肖文,张先锋
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Assessing differences among elasmobranch nurseries to aid conservation based on a genomics framework
Conservation Biology, EarlyView.Abstract Elasmobranch nurseries often differ in environmental conditions, demographics, and use patterns. These differences affect the distribution of genetic variation among nurseries. However, conservation and management strategies often fail to account for such differences because they are difficult to characterize.
Dominic G. Swift +8 more
wiley +1 more source
Auto-focus technology and its application based on image processing
, 2009 Auto-focusing technique is an important method to improve the precision,intelligentization,automatization for the indentation diameter measurement.The paper introduces an auto-focus method of indentation diameter measurement based on image processing ...
Chen, Xiaomei, Yang, Tao, Zuo, Yong
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野生动物学报, 2017 根据1971～2013年北京动物园圈养平原斑马的数据,应用种群管理软件SPARKS v1.6和PMx v1.0对北京动物园斑马圈养种群进行数据整理、统计学和遗传学分析。结果显示该种群数量呈现稳定缓慢增长的状态。目前,北京动物园斑马种群面临的问题主要为性别比例偏离了斑马固有的一雄多雌的种群结构,雄性个体较多; 基因多样性丢失较快。奠基者的后代数明显不均衡,导致现今基因多样性下降至83%,并存在大量半同胞间的近亲繁殖,且现有可配对个体严重不足。1岁前是幼龄斑马的死亡高峰期,流产、死胎为死亡主要原因 ...
由玉岩 周军英 杜 洋 李 莹 曹长雷
doaj
Habitat and spatial trends of U.K. wintering waterbird populations over 50 years
Conservation Biology, EarlyView.Abstract The United Kingdom is an important wintering ground for millions of waterbirds. Most U.K. wintering waterbird populations increased between 1970 and the mid‐1990s, but declined thereafter. We examined U.K. population indices in 46 wintering waterbird species in two 25‐year periods, 1970–1994 and 1995–2019, to identify which waterbird groups ...
Blaise Martay +8 more
wiley +1 more source
, 1985 为了了解长江中白鱀豚的分布状况及种群数量,从1978年至1983年1月止,先后9次在长江中、下游(宜昌至南通)的干流进行了白鱀豚的生态考察,并到汉江和鄱阳湖、洞庭湖等水域查访有无白鱀豚活动的情况,依据考察所得资料,对长江白鱀豚群体的数量作了初步剖析。 通过考察,到1983年初为止,中游最上是在湖北枝城,约距长江口1,613公里的江段和下游最下是江苏太仓浏河口距长江口24公里的江段都有白鱀豚的活动。白鱀豚种群约156头,20个群体,分布在长江中、下游的17个江段里,在安庆一黑砂洲南水道约170公里及嘉鱼 ...
林克杰,陈佩薰,华元渝
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四川大学学报. 自然科学版, 2004 利用MonteCarlo方法,模拟了川西平原农田啮齿动物群落变量的总和、年间和月间变动情况及统计学特征,其变量是:物种数、生物量、物种多样性和均匀性.真实群落4个变量的所有值均在模拟群落变量的95%置信区间内.物种数和物种多样性显示出了相似的变动规律.真实群落4个变量与模拟群落4个变量也显示出了相似的变动规律.当零假设为这些变量服从正态分布时,用单样本Kolmogorov Smirnov方法检验,得到的结果与偏度和峭度显示的结果并不完全一致.结果说明,要估计一个变量的置信区间,需要有足够大的样本含量.
曾涛 +5 more
doaj
Uncovering correlates of decline and critical refuges for a threatened terrestrial mammal
Conservation Biology, EarlyView.Abstract Globally, the geographic ranges of numerous species are contracting. Identifying spatiotemporal patterns of threat impact can illuminate why species decline in some parts of their range but persist in others. We developed a correlative approach to identify species’ response thresholds and locate ecological refuge areas associated with ...
Natalya M. Maitz +5 more
wiley +1 more source