Stomatal density, anatomy and nutrient concentrations of Scots pine needles are affected by elevated CO₂ and temperature

Abstract

), at elevated temperature (ambient + 2·8-6·2 ∞ ∞ ∞ ∞ C depending on the time of the year) and in a combination of elevated CO 2 and temperature in closed-top chambers. The treatments were started in August 1996. At elevated temperature, the needles that were grown in the first year (i.e. the 1997 cohort) were thinner, had thinner mesophyll in the abaxial side, thinner vascular cylinder and lower stomatal density than those grown at ambient temperature. The proportion of mesophyll area occupied by vascular cylinder or intercellular spaces were not changed. Lower stomatal density apparently did not lead to decreased use of water, as these needles had higher concentrations of less mobile nutrients (Ca, Mg, B, Zn and Mn), which could indicate increased total transpiration. In the 1997 and 1998 cohorts, elevation of temperature decreased concentrations of N, P, K, S and Cu. In the 1999 cohort, contradictory, higher concentrations of N and S at elevated temperature may be related to increased nutrient mineralization in the soil. Elevation of CO 2 did not affect stomatal density, needle thickness, thickness of epidermis or hypodermis, vascular cylinder or intercellular spaces. Concentrations of N, P, S and Cu decreased at elevated CO 2 . Reductions were transient and most distinct in the 1997 cohort. The effects of CO 2 and temperature were in some cases interactive, which meant that in the combined treatment stomatal density decreased less than at elevated temperature, and concentrations of nutrients decreased less than expected on the basis of separate treatments, whereas the thickness of the epidermis and hypodermis decreased more than in the separate treatments. In conclusion, alterations in the anatomy and stomatal density of Scots pine needles were more distinct at elevated temperature than at elevated CO 2 . Both elevated CO 2 and temperature-induced changes in nutrient concentrations that partly corresponded to the biochemical and photosynthetic alterations in the same cohorts (

Physiological responses of Abies faxoniana populations from different elevations to increased CO2 and N application

“…Elevated CO 2 was found to induce a decrease in SLA in this study, which is consistent with previous studies (Ainsworth and Rogers 2007;Zhao et al 2011). A low SLA, owing to the accumulation of starch or an increase in the number of palisade cell layers, limits CO 2 diffusion to carboxylation site (Luomala et al 2005). The degree of increases in SLA by elevated CO 2 varies depending on the functional group and environment (Ainsworth and Rogers 2007).…”

“…C and N are essential for plant growth and nutrition acquisition and critical for the adaptability and productivity of plants when facing changing environments. Altered photosynthesis and SLA caused by elevated CO 2 and N application affect the use of mineral nutrients (Luomala et al 2005). The shift of C concentration under elevated CO 2 does not always show a certain trend (Poorter et al 1997;Stitt and Krapp 1999;Herrick and Thomas 2001;Körner 2003).…”

Anatomical structure and localisation of lignin in needles and shoots of Scots pine (Pinus sylvestris L.) growing in a habitat with varying environmental characteristics

“…Today micro structural research is very important because the first responses to stress occur at the cell level (Sutinen, 1998;Butorina & Mozgalina, 2004;Luomala et al, 2005). Research of the physiological and biochemical processes occurring in the cells and tissues of the needles can significantly supplement the knowledge of the mechanisms and processes responsible for the tree tolerance to stress conditions.…”

Long-term effects of stem girdling on needle structure in Scots pine

“…For example, Scots pine needles growing on dunes with poor water availability had An values similar to those of trees 411 DAG (Lukjanova & Mandre 2008). In the present study, the mean values of D1 (0.56 mm) and D2 (0.91 mm) for control trees were at the lower end or below the range reported for adult Scots pine trees (0.4-0.72 mm and 1.13-1.32 mm, respectively - Lin et al 2002, Luomala et al 2005, Lukjanova & Mandre 2008. Interestingly, the reactions of D1 and D2 in response to girdling differed, as only D1 was observed to have decreased in needles 411 DAG.…”