生态脆弱带波动性、人口压力、脆弱度之间的关系

中国北方农牧交错带自然经济系的高波动性是生态脆弱带的显著特征之一。系统的波动性、人口压力、脆弱性三者之间在空间分布和成因上均有密切的联系。坝上后山地区粮食单产的波动性高,并自南向北递增;而以农牧业总产值为代表的土地生产力的波动性与粮食的波动性正好相反,从牧区向农牧区逐渐加大,在张北尚义一带形成高中心。在温饱型的热量营养标准下,人口的绝对和相对超载状况同土地生产力的波动性成正比,线笥相关在０．８３以     

6种猛禽消化系统的比较研究

对6种猛禽(普通鵟Buteo buteo、毛脚鵟B.lagopus、红隼Falco tinnunculus、长耳鸮Asio otus、短耳鸮A.flammeus和鸮Bubo bubo)的消化系统形态结构进行了解剖测量和比较,以了解鸟类消化系统形态结构与食性的关系.结果显示,长耳鸮的消化管最长,是体长的2.08倍;鸮的消...     

蒙古沙冬青对灰斑古毒蛾重复取食响应的代谢组学分析

植物对同种昆虫重复取食做出更有效的响应是植物适应自然界虫害周期性爆发的重要策略。为了研究蒙古沙冬青对其主要害虫灰斑古毒蛾幼虫重复取食响应的代谢基础,本实验采用基于核磁共振（NMR）的代谢组学技术,分析了遭受同一年不同代灰斑古毒蛾幼虫取食的蒙古沙冬青叶片和对照组幼苗叶片的代谢差异。结果表明,仅遭受第一代幼虫取食叶片在第二代幼虫期与对照之间代谢物存在较小差异,而仅遭受第二代幼虫取食叶片与遭受两代幼虫取食叶片代谢差异显著,仅遭受第一代与仅遭受第二代幼虫取食的植株相邻分枝叶片差异显著。另外,只有仅遭受第二代幼虫取食组幼苗表现出处理叶片与相邻分枝叶片的显著代谢差异,并且这种代谢差异为总体代谢的变化,而并未表现为特定代谢物含量变化。由此可见,蒙古沙冬青能在代谢水平以很小的代谢变化来保存昆虫取食信息,在遭受同种昆虫取食后,代谢差异被放大,而且这种信息保存在遭受取食叶片中表现更明显。     

Migration patterns of the Osprey Pandion haliaetus on the Eastern European–East African flyway

We analysed migration strategies of the Osprey Pandion haliaetus on the poorly studied Eastern European–East African flyway. Four adult birds were equipped with GPS-based satellite-transmitters or data-loggers in their breeding sites in Estonia (north-eastern Europe) and tracked to their wintering grounds in Africa and back, during up to six migration cycles. Departure times, migration routes, as well as wintering and stopover sites varied remarkably between individuals but not much between years. Stopovers (2–30 days) were made mostly in Europe and less in the Middle East (Turkey) and north-eastern Africa (Egypt). The Ospreys did not avoid flying long distances over the sea, and the sea was crossed four times during the night. The current study adds to current knowledge on Osprey migration and should help to concentrate actions on protecting important flyways and stopover locations.     

气候波动和土地覆盖变化对广东省植被净初级生产力的相对影响

为深入理解人类活动对陆地生态系统的影响,采用CASA(Carnegie-Ames-Stanford Approach)模型估算广东省2000、2005和2010年实际植被净初级生产力(Net primary productivity,NPP),并基于情景模拟法估算气候和土地覆盖类型稳定条件下的植被NPP,对气候波动和土地覆盖变化在植被NPP变化中的相对贡献进行了研究。结果表明:太阳辐射对植被NPP具有显著的正向控制作用,气温与植被NPP表现为显著负相关,降水不是该区域植被生长的限制性因子;各气候因子与植被NPP的相关性具有季节和区域差异性。在气候不变条件下,土地覆盖变化整体上增加了NPP,对NPP变化的相对贡献与城市扩张格局相类似,不同生态区存在差异性,以珠三角区的贡献最大。总之,气候波动对NPP变化的相对贡献较为复杂,取决于气候因子的波动特征以及与NPP的相关性;其它因子(城市热岛、农耕活动和园林管理等)对NPP变化的相对贡献存在很多不确定性,整体上增加了NPP。     

水热波动和土地覆盖变化对东北地区植被NPP的相对影响

研究水热波动和土地覆盖变化对植被净初级生产力(Net Primary Productivity, NPP)的影响对于估算陆地碳循环及其驱动机制具有重要意义。利用MODIS遥感影像获得的时间序列NPP和土地覆盖产品,结合气象观测数据(气温和降水),采用相关分析、回归分析和空间分析相结合的方法,研究2000—2015年东北地区植被NPP的时空变化特征,并定量评估水热波动和土地覆盖变化对该地区植被NPP的相对影响。研究结果表明,2000—2015年东北地区植被NPP呈波动上升趋势,从2000年的369.24 g C m^-2 a^-1增加到2015年的453.84 g C m^-2 a^-1,平均值是412.10 g C m^-2 a^-1,年际增加速率为4.54 g C m^-2 a^-1。近16年来东北地区年均植被NPP空间上呈现南高北低、东高西低的分布格局,整体变化趋势以增加为主,其中轻微增加面积占该地区总面积的45.9%。不同...     

Effects of Conspecific Presence on Arrival and Use of Hosts in Ceratitis capitata Flies

To reach a better understanding of the factors that affect Mediterranean fruit flies', Ceratitis capitata (Wiedemann) (medflies'), arrival at and use of hosts, we evaluated the alighting and boring propensity of sexually mature high-egg load medfly females that were grouped with conspecifics or held in isolation for 4 days prior to testing. To avoid confounding effects that may have been responsible for conflicting results in previous studies, we exposed groups of free-foraging females to odorless artificial fruit (parafilm-covered agar spheres) in a rotating cage containing small potted host trees and kept experimental intervention to a minimum. Our protocol involved releasing cohorts of 24 females in a patch containing only two such low-quality hosts. In such circumstances, grouped females preferred to alight in significantly greater numbers on artificial fruit occupied by conspecifics than on unoccupied hosts and displayed a significantly greater propensity to oviposit in fruit in the presence than the absence of conspecifics. We did not detect differences in egg load or body size between intruders and residents or between winners and losers of contests. We conclude that as in adaptive superparasitism, the presence of conspecifics may enhance the propensity of fruit-foraging medflies to alight on and use scarce low-quality hosts.     

Domestic chicks' runway responses to video images of conspecifics

Because chickens are highly social animals, live conspecifics are often used to provide an incentive or goal in studies of gait, sociality or fear that require the bird to traverse a runway. However, the variable behaviour of the stimulus birds can influence the approach/avoidance responses of the test birds and thereby confound the results. Because chickens modify their behaviour readily and appropriately to a variety of video images, including social stimuli, we asked if video playback might represent easily controllable and standardized alternatives to live birds. Female ISA Brown chicks were housed in groups of eight and then exposed to a blank illuminated television for 10 min per day from 2 to 7 days of age. At 8 or 9 days of age they were placed individually in the start box of a 1.6 m long runway and we recorded their responses to a monitor displaying selected video images that was situated in the goal box at the opposite end of the runway. In Experiment 1 chicks approached a monitor playing the video image and soundtrack of feeding chicks significantly sooner than one of a goal box with the food dish and background noise. In Experiment 2, chicks were exposed to the same video of feeding conspecifics with or without the associated sounds or to a video of the goal box with or without the chick soundtrack. Both the videos of other chicks elicited faster approach than did those of the goal box and the sound and silent versions were equally attractive. Adding the soundtrack of feeding chicks to the goal-box video failed to increase its attractiveness. The present results suggest that chicks are attracted towards televised images of other chicks. They also indicate that the visual and auditory components of the video stimuli did not exert additive effects and that approach reflected attraction to the visual image. Collectively, our findings suggest that video playback of selected social stimuli, such as feeding conspecifics, could be a valuable tool in tests requiring voluntary locomotion along a predetermined path.     

Management-related stress in the red-shouldered hawk

Disturbance stress can prevent or disrupt successful management of captive birds of prey. Using heart rate as an indicator of stress, two female red-shouldered hawks (Buteo lineatus) were monitored via radio telemetry. Spontaneous heart rate fluctuations in response to stressors involved in management-related activities, as well as some in response to naturally occurring activities, were recorded. In nearly every case, stressors caused dramatic increases in the heart rate of each bird, the magnitude of which was directly related to the degree of human contact involved. The increased heart rates occurred in response to stressors whether or not any behavioral stress symptoms were exhibited. Under the conditions of this study, the use of a falconer's hood did not completely eliminate stress in restrained hawks.