Arrival and pre-nesting period of the snow bunting Plectrophenax nivalis in East Greenland

The first snow bunting males arrive in Northeast Greenland in early April, 6-8 weeks before nesting and 2-4 weeks ahead of the females. At this time temperatures regularly reach −25 to −30°C and snow storms may rage for days. The living conditions during this long-lasting pre-nesting period and its possible function are described and discussed. Based on 781 birds caught, .ringed, and measured, and on observations on phenology, diurnal rhythm, night roosts, etc., it is shown that the age ratio in males is close to 50/50 first living year/adults, that adult males arrive and occupy territories earlier than first year males, that first-year males have shorter wings and are leaner than adult males, that the birds lose weight during spells of inclement weather early in the season, that diurnal rhythm is apparently governed by direct insolation, that males apparently greatly outnumber females in the populations, and that competition for the optimal territories is probably the selective force behind the prolonged pre-nesting period in males.     

辽河三角洲滨海湿地生态系统CO2释放机制

二氧化碳(CO2)是滨海湿地生态系统主要释放的温室气体,对其释放机制的研究是碳循环研究的重要内容。利用LI-8100A土壤呼吸速率检测系统,应用封闭系统的动态气室法,通过2012年5月对辽河三角洲光滩、翅碱蓬(Suaeda salsa)和芦苇(Phragmites australis)2种典型植被湿地类型的系统呼吸通量及其不同实验处理后的呼吸通量研究,探讨在这一季节条件下湿地生态系统的CO2释放途径与机制。研究表明,芦苇湿地呼吸通量高于翅碱蓬湿地,且站立植物的呼吸量的贡献在翅碱蓬湿地仅占24%,在芦苇湿地占40%。特别地,当湿地植物被移除后,湿地系统所产生的CO2通量会显著增高,由此揭示了滨海湿地植物一旦被破坏,其生态系统在短时间内会向大气释放大量的CO2。