Plant population patterns in a glacier foreland succession: pioneer herbs and later‐colonizing shrubs
Plant population patterns in a glacier foreland succession: pioneer herbs and later‐colonizing shrubs
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冰川前陆演替中的植物种群模式：先驱草本植物和后来殖民的灌木
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发表时间：
1993
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通讯作者：
R. Whittaker
中科院分区：
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作者：
R. Whittaker
位于挪威中南部的Storbreen冰川前陆以前曾是一系列社区层面研究方法的主题。重点是对六种主要先锋植物阿拉比斯高山柳树、德香玉高山柳树、双叶棘豆植物、高山早熟禾植物、虎耳草和三叶草以及四种石南灌木白桦、鹅绒委陵菜、毛竹和柳树复合体(沙柳和S兰花)的大小-频率分布的研究。
高山棘豆和丛生虎耳草生长和繁殖的最佳条件似乎几乎是在冰川消融后(7年)，尽管这两个物种在稍老的地形上都达到了最大盖度草本植物的类似模式，尽管它们的最佳出现时间略晚于地形年龄，这表明该物种在演替中的作用不同
在灌木中，一些人口统计和行为模式可被识别为演替特征，其他模式可被解释为与干扰和立地水分关系的历史变化有关的模式。与白桦和毛白桦不同，白桦和沙柳复合体的建立和积累似乎不受环境限制，与白桦和毛白桦相比，白桦是最慢的定居物种，但偶尔早期的定居者看起来健康而多产，表明在建立点上有很强的环境筛子。不同灌木物种的种群格局差异很大。最显著的共同特征是在建立模式中通过营养方式建立分株在前陆内的老土地上(最大地势为230a)越来越多，但只有在前陆以外的成熟荒地才是其特有的建立模式。除了这种模式外，毛竹的营养建立在所有研究的条件下都是非常罕见的。讨论了种群现象、种子扩散和生活史特征在演替变化中的重要性。结论是，物种更替过程中既有异源因素，也有自生因素，虽然在实践中这两类因素很难分开，但在植被发育的后期，自生因素变得更加重要，物种与环境的关系变得更加紧密
Glacier forelands provide valuable sites for the study of patterns and processes of primary succession The Storbreen glacier foreland, south-central Norway, has previously been the subject of a suite of community-level approaches Here the focus is population-level studies of six key pioneer plants Arabis alpina, Deschampsia alpina, Oxyria digyna, Poa alpina, Saxifraga cespitosa and Trisetum spicatum and four heath shrubs Betula nana, Empetrum hermaphroditum, Phyllodoce caerulea and Salix complex (Salix glauca and S lanata) Size-frequency distributions are used as indicators of population phenomena
The optimal conditions for growth and fecundity of Arabis alpina and Saxifraga cespitosa appear to be almost immediately upon deglaciation (< 7 yr), although both achieve their maximum cover on slightly older terrain A similar pattern was noted for the grasses, although their optima come at slightly later times Population phenomena in Oxyria digyna could not be related to terrain age, indicating a differing role of this species within the succession
Among the shrubs a number of demographic and behavioural patterns are identifiable as successional features, and other patterns are explicable in relation to changing histories of disturbance and site moisture relationships Establishment and build-up in Empetrum hermaphroditum and Salix complex do not appear to be environmentally constrained, in contrast to Betula nana and Phvllodoce caerulea Betula nana is the slowest species to colonize, but occasional early colonists appear healthy and fecund, pointing to a strong environmental sieve at the point of establishment The population patterns varied considerably among the shrub species, the most striking common feature being in mode of establishment Establishment of ramets by vegetative means occurs increasingly on older ground within the foreland (maximum terrain age 230 yr) but only in sites of the mature heath outside the foreland is it the characteristic mode of establishment In exception to this pattern, vegetative establishment of Phyllodoce caerulea is very rare in all conditions studied Discussion focuses upon the importance of population phenomena, seed dispersal and life-history characteristics in successional change It is concluded that processes involved in species turnover include both allogenic and autogenic elements and that although the two classes are difficult to separate in practice, autogenic factors become more significant whilst species-environment relations become tighter in later phases of vegetation development