Geoecology of Erratic Lichens of Xanthoparmelia vagans in an equatorial Andean Paramo

A population of 166 lichens of Xanthoparmelia vagans (Nylander) Hale, an obligatory erratic species, was investigated at 4530 m in the Venezuelan Andes. Lichen size and shape were strongly correlated; larger specimens were less spherical and compact than smaller ones. This was related to a greater frequency of disturbance – mainly by wind and frost – of small lichens, which are transported more easily than larger, heavy ones. Constant movement produces nearly spherical specimens, but as lichens grow larger, they are rotated less frequently and rest on a single side for increasingly longer periods; these immobile lichens become progressively more flattened and lenticular in shape. Many large lichens had two distinctive sides, an upper and a lower one, with different coloration. The upper face was pale yellowish green to olive gray (Munsell 5Y 8/4–5/2), the lower one black to very dark brown (10YR 2/1–2/2). Small lichens usually showed no differences between sides. Color variation is also induced by lichen movement. In frequently rotating lichens, thalli grow evenly in all directions due to a uniform insolation. In stationary lichens, thalli remain permanently oriented facing upwards, and their upper and lower sides diverge in coloration. The largest lichens break up easily. Some large specimens were in the process of fragmentation; these had a distinctive kidney-shaped form. Experimental splitting of 16 lichens showed that reduction in size by fragmentation also results in more equant specimens than the original ones. Laboratory experiments on aeolian transport indicated that wind speeds in the paramo are capable of carrying the erratic lichens, but soil areas covered by soil nubbins (miniature mounds produced by needle ice) can trap moving lichens, and greater wind velocities are then needed to re-mobilize them. Lichens were able to quickly absorb and store large amounts of water. Large lichens retained less water than small ones, but lost moisture at much slower rates. Needle-ice growth delivers water to the paramo soil surface, where lichens can readily imbibe it. The water relations of Xanthoparmelia, considered to be ecologically crucial for lichen growth and survival, are discussed in detail.     

近年来中国鸟类野外新纪录的解析

过去若干年里,在中国记录的野生鸟类物种数一直处于增长之中,特别是在2005年《中国鸟类分类与分布名录》第一版出版之后到2013年,又有多个中国鸟类新记录被发现。有部分新纪录已经被收录到2011年出版的《中国鸟类分类与分布名录》第二版之中,但一些新纪录在中国的记录状况、分布等信息还不为广大鸟类学工作者所熟知。本文对这些纪录的分类、分布状况进行了系统性总结,在总结的基础上我们发现,在这些新纪录主要分布于三个热点地区,包括西部边境省区(新疆、西藏、云南、广西),沿海三省市(河北、天津、福建)及台湾。其中,出现在西部的新纪录物种的已知分布区邻近中国,部分种类极可能在中国境内繁殖、越冬和过境;而来自沿海和台湾的新纪录物种原有分布区距离中国较远,在中国多为偶见的迷鸟。未来这些地区仍将是产生中国新纪录的热点地区。