两种短命植物春萌秋萌个体生态生物学特征比较

短命植物是新疆北部荒漠生态系统中重要组成部分,对稳定该区沙漠生态系统、丰富物种多样性具有重要的意义。以往对短命植物的研究多集中在春季萌发的短命植物,秋季萌发的短命植物研究很少,对秋季萌发短命植物和春季萌发短命植物的生态生物学特征的异同以及它们对稳定荒漠生态系统的意义缺乏了解。选择小车前(Plantago minuta)和尖喙牻牛儿苗(Erodium oxyrrhynchum)为研究对象,采用野外定点标记观测和室内分析结合的方法,研究了两种短命植物春季萌发和秋季萌发两种表现型在冠幅、生物量、物候期、菌根侵染率等生态生物学特征方面的差异性。结果表明:秋季萌发的小车前和尖喙牻牛儿苗能够在覆雪下越冬,其单株的冠幅、叶片数量、干重等均远远大于同一时期生长的春季萌发的小车前和尖喙牻牛儿苗,尤其是单株结种数量更是比春季萌发小车前和尖喙牻牛儿苗的高13.0和4.4倍;秋季萌发的小车前和尖喙牻牛儿苗的花期分别比春季萌发小车前和尖喙牻牛儿苗早14和7 d,植株黄枯期和成熟期分别提早3和4 d;此外,秋季萌发小车前和尖喙牻牛儿苗各时期的菌根侵染率也显著高于同期春季萌发小车前和尖喙牻牛儿苗。本研究得到以下结论:秋季萌发的小车前和尖喙牻牛儿苗在稳定和扩大其后代种群繁衍能力、提高防风固沙能力、稳定荒漠生态系统等方面具有重要意义。

ECOLOGICAL AND BIOLOGICAL DIFFERENCES BETWEEN SPRING AND AUTUMN PLANTS OF TWO DESERT EPHEMERALS

Aims Ephemerals are important in desert ecosystems,playing a key role in ecosystem stabilization.Previous research has concentrated on spring ephemerals.Little is known about biological and ecological characteristics of ephemerals that germinate in spring and autumn and about the significance of autumn ephemerals in stabilizing desert ecosystems.Methods We marked plants of Plantago minuta and Erodium oxyrrhynchum,species that germinate in spring and autumn.We investigated their crowns,leaves and phenological characteristics in the field during their growing seasons and measured their dry weights and mean arbuscular mycorrhizal colonization rates in the laboratory.Important findings Leaves,flowers,fruits,seeds and dry weights of autumn plants are larger than those of spring plants.For example,in autumn P.minuta and E.oxyrrhynchum produced 13.0 and 4.4 times as many seeds and flowered 14 and 7 days earlier,respectively,than spring plants.In addition,mean arbuscular mycorrhizal colonization rates were higher in autumn than spring plants,accelerating the absorption of phosphorus.Autumn plants had greater capability of reproduction and ecosystem stabilization,allowing them to play an important role in stabilizing the desert ecosystem.