尖喙牻牛儿苗夏萌植株性状与生物量分配

Functional traits and biomass allocation of summer⁃germinated plants of Erodium oxyrhinchum

荒漠短命植物具有异时萌发现象,除在春天萌发外,秋天偶尔也会萌发,但在夏季萌发的植株十分罕见。降水格局的改变使得短命植物夏萌植株出现的概率增加,然而,夏萌植株的生活史策略仍不清楚。选择古尔班通古特沙漠南缘沙垄4个不同坡位、坡向(西坡底部、西坡中部、东坡中部、东坡底部),以短命植物层片中的优势物种尖喙牻牛儿苗夏萌植株为研究对象,解析尖喙牻牛儿苗夏萌植株在不同生长时期关键性状和生物量分配的动态变化,并探讨沙垄不同坡位、坡向的协同效应。结果表明:(1)尖喙牻牛儿苗夏萌植株跨过冬季后在早春完成生活史,生活周期为281.95±3.55 d。(2)在不同生长时期尖喙牻牛儿苗夏萌植株根冠比存在差异,在越冬前根冠比呈现出显著增加趋势(P<0.05),而越冬后呈现显著递减的趋势(P<0.05)。(3)沙垄不同坡位、坡向尖喙牻牛儿苗夏萌植株关键性状存在显著差异,表现为西坡的株高、叶片数量和单株生物量均显著大于东坡,但不同坡位、坡向间根冠比无显著差异。探究沙垄不同坡位、坡向尖喙牻牛儿苗夏萌植株生活史策略对评估气候变化背景下的荒漠生态系统植被动态具有重要意义。

Ephemeral plants germinate at different times in desert.They germinate in spring and occasionally in autumn,but very rarely in summer.Changes of precipitation pattern increase the probability of the occurrence of shortlived summer⁃germinated plants.However,life history strategy of summergerminated plants remains unclear.Therefore,we measured key traits and the temporal variations of biomass allocation of summer⁃germinated plants,Erodium oxyrhinchum,in different growth periods and four different slope positions(the base of the sand dune facing west(BW),the middle of the sand dune facing west(MW),the middle of the sand dune facing east(ME),and the base of the sand dune facing east(BE))in the Gurbantünggüt desert.We further examined the synergetic effects of different slope position and aspect of sand dunes.We found that:(1)The summergerminated individuals of E.oxyrhinchum crossed the winter and completed life cycle in early spring of next year,with a life cycle of 281.95±3.55 days.(2)There were differences in the root/shoot ratio of the summer⁃germinated individuals at different growth stages.The ratio showed a significant increase trend before overwintering(P<0.05),and a significant decrease trend after overwintering(P<0.05).(3)There were significant differences in the key traits of summergerminated individuals in different slope positions and directions of the sand ridge.Plant height,leaf number and biomass per plant on the west slope were significantly greater than those on the east slope,but there was no significant difference in the root/shoot ratio between different slope positions and directions.It is of great significance to explore life history strategy of summer⁃germinated individuals of E.oxyrhinchum in different slope positions and directions of sand ridges for assessing the vegetation dynamics of desert ecosystems under the background of climate change.