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| 1 | The effect of temporal variation in soil carbon inputs on interspecific plant competition显示文摘Aims Release of carbon from plant roots initiates a chain of reactions involving the soil microbial community and microbial predators,eventually leading to nutrient enrichment,a process known as the‘microbial loop’.However,root exudation has also been shown to stimulate nutrient immobilization,thereby reducing plant growth.Both mechanisms depend on carbon exudation,but generate two opposite soil nutrient dynamics.We suggest here that this difference might arise from temporal variation in soil carbon inputs.Methods We examined how continuous and pulsed carbon inputs affect the performance of wheat(Triticum aestivum),a fast-growing annual,while competing with sage(Salvia officinalis),a slow-growing perennial.We manipulated the temporal mode of soil carbon inputs under different soil organic matter(SOM)and nitrogen availabilities.Carbon treatment included the following two carbon input modes:(i)Continuous:a daily release of minute amounts of glucose,and(ii)Pulsed:once every 3 days,a short release of high amounts of glucose.The two carbon input modes differed only in the temporal dynamic of glucose,but not in total amount of glucose added.We predicted that pulsed carbon inputs should result in nutrient enrichment,creating favorable conditions for the wheat plants.Important FindingsCarbon addition caused a reduction in the sage total biomass,while increasing the total wheat biomass.In SOM-poor soil without nitrogen and in SOM-rich soil with nitrogen,wheat root allocation was higher under continuous than under pulsed carbon input.Such an allocation shift is a common response of plants to reduced nutrient availability.We thus suggest that the continuous carbon supply stimulated the proliferation of soil microorganisms,which in turn competed with the plants over available soil nutrients.The fact that bacterial abundance was at its peak under this carbon input mode support this assertion.Multivariate analyses indicated that besides the above described changes in plant biomasses and bacterial abundances,carbon supply led to an accumulation of organic matter,reduction in NO_(3)levels and increased levels of NH_(4)in the soil.The overall difference between the two carbon input modes resulted primarily from the lower total wheat biomass,and lower levels of NO_(3)and soil PH characterizing pots submitted to carbon pulses,compared to those subjected to continuous carbon supply.Carbon supply,in general,and carbon input mode,in particular,can lead to belowground chain reactions cascading up to affect plant performance. | Stav Livne-Luzon Hagai Shemesh Osnat Gilor Ofer Ovadia | 2016 | Journal of Plant Ecology2016，9，5： | 1 |
| 2 | 脉状方解石及其流体包裹体的同位素组成:对确定古水文系统、构造事件和矿脉形成过程的意义显示文摘确定了构造活动区发育的第三纪矿脉系统中方解石的同位素组成及其流体包裹体的氘含量。矿脉系统由3组不同走向的方解石脉(Ⅰ、Ⅱ、Ⅲ)组成,根据穿切关系确定了它们的相对年龄。每组脉具有其特征的方解石δ^(18)O和δ^(13)C值:第Ⅰ组为-7.9‰和+1.59‰;第Ⅱ组为-15.3‰和+0.54‰;第Ⅲ组为-15.9‰和+1.73‰,而最老的一组(Ⅰ)的流体包裹体δD(-23.9‰)与以色列海岸平原雨水和地下水的流体包裹体δD相似,最年轻的一组(Ⅲ)的δD值(-49.6‰)与Hermon山的雨水和地下水的相似,可以认为δD的差异是由于同位素“高程效应”造成的。结论是,水文系统的主要变化与Hermon山区的形成及其高程有关,利用大气降水中δ^(18)O和δD之间的关系计算了第Ⅰ组(35℃)第第Ⅱ组(64℃)矿脉的形成温度,形成温度表明本区矿脉发生在浅部(1.7km)。方解石δ^(18)C表明,围岩是脉状方解石的来源,并且由于压力释放δ^(13)C有约1‰的变化。根据方解石的溶解度取决于压力和造成水力压裂及压力下降后不断增加的孔隙压力循环,讨论了矿脉形成的比较普遍的模式。 | Aldo Shemesh Hagai Ron Yigal Erel 周薇 | 1994 | 国外铀金地质1994，11，4： | 0 |
| 3 | 季节性火烧塑造了东地中海地区林地的可萌发种子库群落显示文摘本研究探索了在典型东地中海林地中,季节性火烧是否以及如何与微生境类型(即黄连木属(Pistacia)灌木下、岩蔷薇属(Cistus)灌木下或林冠间隙)相互作用,从而影响可萌发种子库(germinable soil seed bank,GSSB)群落的组成。我们进行了一项野外实验,其中包括预定的春秋火烧,然后利用从火烧地块和相邻未火烧对照地收集的土壤样本对种子萌发的模式进行定量。研究结果表明,秋烧期间,土壤温度比春烧的要高,而春烧期间土壤温度则比秋烧的变化更大。火烧导致可萌发种子库整体的密度、丰富性和多样性降低。秋烧地块内黄连木属和岩蔷薇属灌木的可萌发种子库丰富性和多样性显著降低,这些模式主要表现在一年生植物中。在火烧样地收集的样本中,低矮灌木的可萌发种子库密度更高,在黄连木属和岩蔷薇属灌木下采集的样品中,这种模式更为明显。在季节性火烧与出现的独特物种会共同导致可萌发种子库的群落组成发生显著的变化。这些结果表明,季节性火烧与空间异质性互相作用,主要通过对一年生植物和低矮灌木的可萌发密度的差异效应来影响可萌发种子库群落的组成。这些研究发现意味着,过去几十年东地中海盆地的季节性火烧频率上升,可能转化为进化生态选择压力的变化,并对这一独特生态系统内的植物产生影响。 | Neta Manela Hagai Shemesh Yagil Osem Yohay Carmel Chanoch Soref Anat Tsafrir Ofer Ovadia | 2022 | Journal of Plant Ecology2022，15，1： | 0 |
| 4 | 不同花粉来源对一年生植物种子性状和扩散能力的影响显示文摘与扩散有关的性状进化和表达与其他生活史功能交织在一起,并在各种生理约束条件下表现出来。这种关系可以在近交水平和扩散性之间得到预测,而且在解剖学和个体发育上联系在一起,从而使某个选择压力可能影响另外的一个。虽然近交对生殖成功和扩散策略的影响都引起了广泛关注,但只有少数研究同时考虑了这两者。此外,此类研究通常依赖于繁殖和扩散的表示:使用自交与异源杂交表示繁殖水平,使用扩散比表示扩散策略。本研究利用菊科Qep/ssancta的授粉实验,以两种不同的方式扩展繁殖和扩散的二分表示法。首先,我们使用授粉处理来表示一种统一连续体,即从亲缘授粉的自交到距离较远的邻居授粉。其次,我们不仅测量了繁殖成功率和扩散比,还测量了一整套连续的与形态和扩散相关的性状。研究结果显示,头状花序的比例,以及扩散的和非扩散的瘦果在自花传粉处理中都显著低于异源杂交处理。尽管自花授粉的植物很少产生不扩散的种子,但花粉来源对扩散比的影响统计上不显著。瘦果的生物量随亲本植物之间的距离增加而增加,但冠毛宽度没有增加,从而导致授粉对下落速度的影响不显着。总之,花粉来源主要影响与生殖产量有关的性状,但对主要与扩散有关的性状没有显著影响。繁殖和扩散性状对花粉来源变化响应的这种差异表明,与扩散有关的选择可能很弱和/或被其他因素所掩盖。 | Efrat Dener Hagai Shemesh Itamar Giladi | 2021 | Journal of Plant Ecology2021，14，3： | 0 |
| 5 | The effects of temporal variation in soil carbon inputs on resource allocation in an annual plant显示文摘Aims Resource allocation in plants can be strongly affected by competition.Besides plant–plant interactions,terrestrial plants compete with the soil bacterial community over nutrients.Since the bacterial communities cannot synthesize their own energy sources,they are dependent on external carbon sources.Unlike the effect of overall amounts of carbon(added to the soil)on plant performance,the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown.We hypothesize that continuous carbon supply(small temporal variance)will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients.On the other hand,carbon pulses(large temporal variance)are expected to cause oscillations in bacterial biomass,enabling plants temporal escape from competition and possibly enabling increased growth.We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output.We also expected this effect to be noticeable only when sufficient nutrients were present in the soil.Methods Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils,with or without slow-release fertilizer,subjected to one of the following six carbon treatments:daily(1.5mg glucose),every other day(3mg glucose),4 days(6mg glucose),8 days(12mg glucose),16 days(24mg glucose)and no carbon control.Important Findings Remarkably,carbon pulses(every 2–16 days)led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils.Consistent with our prediction,these effects were noticeable only when sufficient nutrients were present in the soil.Furthermore,soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass.We interpret this to mean that when the amount of available nutrients is low,these nutrients are mainly used by the bacterial community.Our results show that temporal variation in soil carbon inputs may play an important role in aboveground–belowground interactions,affecting plant resource allocation. | Hagai Shemesh Uri Ben-Yosef Stav Livne Ofer Ovadia | 2016 | Journal of Plant Ecology2016，9，1： | 0 |
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