文章基本信息

标题：Characterizing Betula Litwinowii Seedling Microsites at the Alpine-Treeline Ecotone, Central Greater Caucasus Mountains, Georgia
其他标题：Characterizing Betula Litwinowii Seedling Microsites at the Alpine-Treeline Ecotone, Central Greater Caucasus Mountains, Georgia
本地全文：下载
作者：Nicole M. Hughes ; Daniel M. Johnson ; Maia Akhalkatsi 等
期刊名称：Arctic, Antarctic, and Alpine Research
印刷版ISSN：1523-0430
电子版ISSN：1938-4246
出版年度：2009
卷号：41
期号：1
页码：112-118
DOI：10.1657/1523-0430-41.1.112
摘要：Seedling establishment is an important factor dictating the altitudinal limits of treeline species. Factors which affect seedling mortality and survival, however, have yet to be fully characterized, especially for deciduous treeline species. Here we describe microsite characteristics of successfully established Betula litwinowii seedlings at the alpine-treeline ecotone. Possible harmful effects of sky exposure on seedling physiology (i.e. photoinhibition of photosynthesis) were also examined, as well as possible facilitative effects of co-occurring Rhododendron caucasicum shrubs on northern slopes and microtopographical depressions (mainly watercourses) in ridgetop meadows. On northern slopes, seedling density was highest in newly exposed soils, with 90% of the youngest seedlings (80% sky exposure), suggests that sky exposure is likely not a significant factor affecting seedling mortality in B. litwinowii , in contrast to results reported for conifer and broadleaf evergreen species at treeline. A higher photosynthetic capacity and a deciduous life history may provide both tolerance and avoidance to the physiological stresses associated with high sky exposure for B. litwinowii seedlings, and other factors, such as soil moisture, more likely account for successful establishment within microtopographical depressions and R. caucasicum thickets.