Effects of soil and air drought on growth, plant water status and leaf gas exchange in three Mediterranean cedar species: Cedrus atlantica, C. brevifolia and C. libani

Abstract

Three-and four-year-old potted, greenhousegrown cedar seedlings were subjected to two different watering regimes: half received full water supply and the other half was submitted to moderate drought (50% of the full water supply). Height growth was the greatest for C. atlantica and the most-limited for C. brevifolia in the well-watered set. However, in the dry set, height growth was less affected by drought conditions for C. brevifolia than for C. atlantica. Cedrus libani gave intermediate results for both watering regimes. Moderate drought provoked a decrease in osmotic potential at full leaf turgor and a long-lasting osmotic adjustment. When irrigation was withheld completely to induce severe soil drying, gas exchange decreased and then stopped at predawn water potentials of − 3.0 MPa for C. brevifolia, between − 2.6 and − 2.8 MPa for C. libani, and at − 2.4 MPa for C. atlantica, irrespective of watering regime. For all species, the dry set showed lower net photosynthesis (A) and stomatal conductance (g s ) than the plants in the wellwatered set. A and g s responded to variations in atmospheric water-vapour pressure deficit (VPD). As VPD increased, A and g s decreased, and this trend was proportionate to initial values at low VPD, but remained independent of previous watering treatments, plant water status or species. To conclude, C. brevifolia appears to be a species with limited growth potential but strong soil drought tolerance whereas C. atlantica has strong growth potential when an adequate water supply is available but is more sensitive to soil drought. Communicated by R. Matyssek M. Ladjal · N. Deloche · R. Huc · M. Ducrey ( ) INRA, UR629 Unité de Recherches Forestières Méditerranéennes, Domaine Saint Paul,

Cedrus libani: A promising tree species for Central European forestry facing climate change?

“…In spite of very low rainfalls (sum of precipitation 68 mm) and high temperatures (mean air temperature 18°C) at Elmali Tree ring width measurements between 1988 and 1993 were not possible for all trees because the stem center was missed by coring (1988: n = 10, 1989: n = 12, 1990: n = 16, 1991: n = 17, 1992: n = 18, 1993: n = 19, 1994-2010: n = 20 during summer (DOY 150 until DOY 250) and compared with 245 mm and 16.6°C, respectively in Bayreuth, radial growth was observed at Elmali during the entire observation period. This is also in accordance with the observations of Ladjal et al (2007) on Cedrus height growth. In addition to its drought tolerance, the required minimum water supply for C. libani in Elmali during the drought summer may be further provided by fine soils in deep and creviced limestone formations which feature a high waterholding capacity (Boydak and Calikoglu 2008).…”

“…stenocoma in the Western Taurus Mountains from SW Turkey) is a tree species with high potential for forestry in Central Europe. Indeed, it can be assumed that differences in growth, tolerance to drought as well as to extreme frost events exist for C. libani, a tree species with a large and very disjunct natural distribution (see also Ladjal et al 2007;Ducrey et al 2008;Bariteau and Vauthier 2007;Huber and Storz 2014). As early as 1939, Schenck advocated test with provenances from the Taurus Mountains and recommended against provenances from Lebanon.…”

Microclimate in forests with varying leaf area index and soil moisture: potential implications for seedling establishment in a changing climate

“…Similarly, soil temperature has been shown to influence root water uptake and thus transpiration rates (Mellander, Bishop & Lundmark 2004). To reduce short-term water demand, stomata often close when soil moisture and/or air humidity are low (Aasamaa & Sõber 2011;Ladjal et al 2007). Effectively, stomatal conductance is usually regulated by a simple negative feedback loop between demand and supply, that is, between vapour pressure deficit of the air (VPD) and soil moisture (MaierMaercker 1998).…”

Detection and discrimination of oil and water deficit-induced stress in maize (Zea mays L.) using spectral and thermal responses

“…A recent study found that when irrigation was withheld to induce severe soil drying, gas exchange decreased and then stopped in three Mediterranean cedar species: Cedrus atlantica, C. Brevifolia and C. Libani (Ladjal et al 2007). An empirical study by Ray and Sinclair (1998) found that the overriding factor determining transpirational response in maize (Zea mays L.) and soyabean (Glycine max L.) to drought stress was soil dryness.…”