Growth reduction after defoliation is independent ofCO2supply in deciduous and evergreen young oaks

• DOI: 10.1111/nph.14484
• Publication Date: 2017-02-27T11:55:02Z
• Authors: Sandra Schmid; Sara Palacio; Günter Hoch
• Keywords: Plant Leaves; 0106 biological sciences; Quercus; Seasons; Carbon Dioxide; Photosynthesis; 15. Life on land; 01 natural sciences; Carbon; Ecosystem

SummaryReduced productivity of trees after defoliation might be caused by limited carbon (C) availability.We investigated the combined effect of different atmosphericCO2concentrations (160, 280 and 560 ppm) and early season defoliation on the growth and C reserves (nonstructural carbohydrates (NSC)) of saplings of two oak species with different leaf habits (deciduousQuercus petraeaand evergreenQuercus ilex).In both species, higherCO2supply significantly enhanced growth. Defoliation had a strong negative impact on growth (stronger forQ. ilex), but the relative reduction of growth caused by defoliation within eachCO2treatment was very similar across all threeCO2concentrations. LowCO2and defoliation led to decreasedNSCtissue concentrations mainly in the middle of the growing season inQ. ilex, but not inQ. petraea. However, also inQ. ilex,NSCincreased in woody tissues in defoliated and low‐CO2saplings towards the end of the growing season.Although the saplings were C limited under these specific experimental conditions, growth reduction after defoliation was not directly caused by C limitation. Rather, growth of trees followed a strong allometric relationship between total leaf area and conductive woody tissue, which did not change across species,CO2concentrations and defoliation treatments.