Foliar plasticity of hybrid spruce in relation to crown position and stand age

Abstract

This study examined the foliar response of putative hybrid Engelmann × white × Sitka spruce (Picea engelmannii Parry × Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carr) needles in relation to crown position and across three stages of development (15, 55, and 145 years). We focused on the morphological and anatomical response, and used physiological measures (photosynthesis and stomatal conductance) to emphasize the important relationship between structure and function. We found that needles from the upper outer crown position were adaptated to reduce stress from evapotranspiration. Trees from the 15-and 55-year-old stands generally responded the most, and trees from the 145-year-old stand responded the least. As they mature, these spruce trees may have reduced ability to adapt to their environment. Some of our results contradict what the literature considers "typical" for sunshade dimorphism in temperate forests. For example, in all stands, sun needles were broader than shade needles and, in the two younger stands, sun needles were larger in area, not smaller, than shade needles. Also, in the youngest stand, stomatal pores were longer on sun needles than on shade needles. There were no definite patterns in stomatal spacing with regard to crown position. Our results are indicative of the strategies adopted to increase competitiveness in a resourcelimited environment. We suggest that, in the 15-year-old stand, neither water nor light is limiting; in the 55-year-old stand, both water and light are highly limiting; and in the 145-year-old stand, water is most limiting.

Morphological and anatomical differentiation in peripheral Pinus sylvestris L. populations from the Carpathian region

“…Plants growing under strong light have well developed palisade parenchyma, thicker leaves, relatively larger leaf area, higher biomass, increased photosynthesis, and lower contents of chlorophyll, carotenoid, and nitrogen (Je et al, 2006;Yang et al, 2007;Huang et al, 2008;Volkova et al, 2010). Structural characteristics of conifer needles are often strongly related to gradients in long-term light availability within canopies and across stands (Richardson et al, 2000;Richardson et al, 2001;Niinemets et al, 2002;Lhotáková et al, 2007;Niinemets et al, 2007). The lower NBRCC and NBRCW values and higher CCH/ NH proportion in peat bog populations and populations growing on rocky substrates can be explained as a response to increasing environmental stress, which is accompanied by a decline in photosynthetic and growth rate, since higher leaf age compensates for low photosynthesis (Schoettle et al, 1994;Reich et al, 1995).…”

Sources of within- and between-stand variability in specific leaf area of three ecologically distinct conifer species

“…Sample trees were selected from three fire-origin stands with approximate ages of 20 years (S20), 60 years (S60) and 140 years (S140). The stands were chosen previously for a related study [34]. The two older stands (S60 and S140) were located within the Date Creek research area managed by the British Columbia Ministry of Forests while the youngest stand (S20) was in an adjacent wildfire known locally as the Ken Fire.…”

Spatial and Temporal Growth Variation of Pinus heldreichii Christ. Growing along a Latitudinal Gradient in Kosovo and Albania

“…Previous studies have shown that in old conifer trees the duration of wood formation is shorter than in younger ones [28]. It is well-known that tree ageing affects carbon allocation to different parts of the plant, reduces the foliar efficiency and gas attributes [29,30]. Thus, decline of photosynthetic rate in old conifer species induce the increasing of climatic sensitivity, especially towards temperatures [31].…”