Low Winter Soil Temperature Affects Summertime Nutrient Uptake Capacity and Growth Rate of Mountain Birch Seedlings in the Subarctic, Swedisn Lapland
Low Winter Soil Temperature Affects Summertime Nutrient Uptake Capacity and Growth Rate of Mountain Birch Seedlings in the Subarctic, Swedisn Lapland
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DOI：
10.1080/15230430.2002.12003514
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发表时间：
2002-11
期刊：
影响因子：
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通讯作者：
M. Weih;P. Staffan Karlsson
中科院分区：
文献类型：
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作者：
M. Weih;P. Staffan Karlsson
冬季不同土壤温度对山地桦幼苗夏季生长速率的影响。czerepanovii）在亚北极瑞典的室外盆栽实验中进行评价。检验的假设是，冬季土壤温度低，可以降低生长季节的养分吸收能力和生长速率的伤害的根系，进一步，根损伤应刺激生长的替代根，这应反映在增加夏季生物量分配到根。山桦树苗暴露于两个土壤温度在冬季通过操纵积雪深度，积累在顶部的盆。冬季最低土壤温度（每小时记录）在“保护”处理（深积雪）中为-1.7 ° C，在“暴露”处理（薄积雪）中为-10.5 °C。处理分别模拟了当地山地白桦林和石南地的土壤温度条件。在6月和7月，暴露处理的相对生长速率（RG）和氮积累速率（RN）低于保护处理。此外，暴露处理的幼苗分配给根的生物量的比例更大相比，保护处理。因此，与保护处理相比，暴露的叶片生长减少。我们的结论是，冬季温度较低的土壤可以导致更强的根损伤，刺激生长的替代根，降低养分吸收能力和生长速度在夏季。与冬季引起根系破坏的其他可能因素相一致，例如，频繁的冻融循环，这里确定的机制可能是重要的生存树苗在亚北极和高山地区，特别是靠近树木。具体讨论了山区桦树幼苗生长和生存在无树的亚北极荒原网站和以上的树木线在北方欧洲。
Effects of different winter soil temperature on summertime growth rate of individual seedlings of mountain birch (Betula pubescens ssp. czerepanovii) were evaluated in an outdoor pot experiment in subarctic Sweden. The hypothesis tested was that low winter soil temperature could decrease growing-season nutrient uptake capacity and growth rate by injury of the root system; further, the root damage should stimulate growth of replacement roots, which should be reflected by increased summertime biomass allocation to roots. Mountain birch seedlings were exposed to two soil temperatures during wintertime by manipulation of snow depth that accumulated on top of the pots. Minimum soil temperature (hourly recordings) during winter was –1.7°C in the “protected” treatment (deep snow cover) and – 10.5°C in the “exposed” treatment (thin snow cover). The treatments simulated the soil temperature conditions of a local mountain birch forest and heath site, respectively. During June and July, the relative growth rate (RG) and nitrogen accumulation rate (RN) in the exposed treatment were lower compared to the protected treatment. In addition, the seedlings of the exposed treatment allocated a greater proportion of biomass to roots compared to the protected treatment. Thus, leaf growth was reduced in the exposed compared to the protected treatment. We concluded that lower winter temperature in soils can result in stronger root injury that stimulates the growth of replacement roots and reduces nutrient uptake capacity and growth rate during summer. In concert with other possible factors causing root disruption during winter, e.g., frequent freeze-thaw cycles, the mechanism identified here might be important for survival of tree seedlings in subarctic and alpine areas, especially near treelines. The implications are discussed specifically for mountain birch seedling growth and survival in treeless subarctic heath sites and above treelines in northern Europe.