Eucalypts are likely to play a critical role in the response of Australian forests to rising atmospheric CO2 concentration ([CO2]) and temperature. Although eucalypts are frequently phosphorus (P) limited in native soils, few studies have examined the main and interactive effects of P availability, [CO2] and temperature on eucalypt morphology, physiology and anatomy. To address this issue, we grew seedlings of Eucalyptus tereticornis Smith across its P-responsive range (6-500 mg kg-1) for 120 days under two [CO2] (ambient: 400 μmol mol-1 (Ca) and elevated: 640 μmol mol-1 (Ce)) and two temperature (ambient: 24/16 °C (Ta) and elevated: 28/20 °C (Te) day/night) treatments in a sunlit glasshouse. Seedlings were well-watered and supplied with otherwise non-limiting macro- and micro-nutrients. Increasing soil P supply increased growth responses to Ce and Te. At the highest P supplies, Ce increased total dry mass, leaf number and total leaf area by ~50%, and Te increased leaf number by ~40%. By contrast, Ce and Te had limited effects on seedling growth at the lowest P supply. Soil P supply did not consistently modify photosynthetic responses to Ce or Te. Overall, effects of Ce and Te on growth, physiological and anatomical responses of E. tereticornis seedlings were generally neutral or negative at low soil P supply, suggesting that native tree responses to future climates may be relatively small in native low-P soils in Australian forests.

中文翻译：

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二氧化碳和高温对土壤磷梯度下桉树形态，生理和解剖响应的影响。

桉树可能在澳大利亚森林对大气CO2浓度（[CO2]）和温度升高的反应中起关键作用。尽管桉树在本地土壤中常常受磷（P）的限制，但很少有研究检查磷的有效性，[CO2]和温度对桉树形态，生理和解剖结构的主要影响和相互作用。为了解决这个问题，我们在两种[CO2]下（环境：400μmolmol-1（Ca），在升高的条件下：640）下，在其P响应范围（6-500 mg kg-1）下播种了桉桉史密斯幼苗，持续120天μmolmol-1（Ce））和两个温度（日/夜环境温度：24/16°C（Ta）和高温：28/20°C（Te）日/夜）处理。幼苗需充分浇水，并提供其他非限制性的大量和微量营养素。土壤磷供应的增加增加了对Ce和Te的生长响应。在最高的磷供应量下，铈增加了总干重，叶片数和总叶面积约50％，而碲增加了叶片数约40％。相比之下，Ce和Te在最低磷供应下对幼苗生长的影响有限。土壤磷的供应不能持续改变对Ce或Te的光合响应。总体而言，在土壤磷供应低的情况下，铈和碲对tereticornis幼苗生长，生理和解剖反应的影响通常为中性或阴性，这表明澳大利亚低磷天然土壤对未来气候的原生树响应可能相对较小。森林。Ce和Te对最低磷供应的幼苗生长的影响有限。土壤磷的供应不能持续改变对Ce或Te的光合响应。总体而言，在土壤磷供应低的情况下，铈和碲对E. tereticornis幼苗生长，生理和解剖响应的影响通常为中性或阴性，这表明澳大利亚低磷天然土壤对未来气候的原生树响应可能相对较小。森林。Ce和Te对最低磷供应的幼苗生长的影响有限。土壤磷的供应不能持续改变对Ce或Te的光合响应。总体而言，在土壤磷供应低的情况下，铈和碲对tereticornis幼苗生长，生理和解剖反应的影响通常为中性或阴性，这表明澳大利亚低磷天然土壤对未来气候的原生树响应可能相对较小。森林。