The partitioning of gross primary production for young Eucalyptus tereticornis trees under experimental warming and altered water availability
The partitioning of gross primary production for young Eucalyptus tereticornis trees under experimental warming and altered water availability
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DOI：
10.1111/nph.15629
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发表时间：
2019-05-01
期刊：
影响因子：
9.4
通讯作者：
Barton, Craig V. M.
中科院分区：
文献类型：
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作者：
Drake, John E.;Tjoelker, Mark G.;Barton, Craig V. M.
碳(C)的分配是影响树木生长和生态系统碳储量的重要生理成分。分配很难衡量，而且它对气候变暖和水资源供应变化等环境变化的敏感度也不确定。我们使用全树箱让圆角桉幼树暴露在+3摄氏度的温度下，并消除了田野中的夏季降水。我们使用详细的生长测量和连续的全冠二氧化碳和水分交换测量来计算碳分配项。在这项为期15个月的实验中，树木从小树苗长到了近9米高。增温促进了生长和叶面积的发育，增加了总初级生产力(GPP)对地上呼吸和生长的分配，而减少了地下分配。消除夏季降水减少了碳的吸收和生长，但不影响GPP的分配。树木利用深层土壤水分，避免强烈的负水势。增温增加了生长呼吸，但维持呼吸适应了动态平衡。即使完全适应了维持呼吸，加温处理的增长也导致了更高的呼吸速率。气候变暖对树木生长的刺激可能涉及增加地上碳分配，特别是叶面积发育，而水分可获得性的减少可能不会刺激向根的分配。
The allocation of carbon (C) is an important component of tree physiology that influences growth and ecosystem C storage. Allocation is challenging to measure, and its sensitivity to environmental changes such as warming and altered water availability is uncertain. We exposed young Eucalyptus tereticornis trees to +3 degrees C warming and elimination of summer precipitation in the field using whole-tree chambers. We calculated C allocation terms using detailed measurements of growth and continuous whole-crown CO2 and water exchange measurements. Trees grew from small saplings to nearly 9 m height during this 15-month experiment. Warming accelerated growth and leaf area development, and it increased the partitioning of gross primary production (GPP) to aboveground respiration and growth while decreasing partitioning below ground. Eliminating summer precipitation reduced C gain and growth but did not impact GPP partitioning. Trees utilized deep soil water and avoided strongly negative water potentials. Warming increased growth respiration, but maintenance respiration acclimated homeostatically. The increasing growth in the warmed treatment resulted in higher rates of respiration, even with complete acclimation of maintenance respiration. Warming-induced stimulations of tree growth likely involve increased C allocation above ground, particularly to leaf area development, whereas reduced water availability may not stimulate allocation to roots.