Variation in needle-trace diameter in respect of needle morphology in five conifer species

Abstract

Needle traces have been used for revealing historical changes in needle longevity of Pinus sylvestris L. and Picea abies (L.) H. Karst. In this paper we compared the needle-trace diameter of five conifer species [Abies sibirica Ledeb., Picea abies, Pinus sylvestris, Pseudotsuga menziesii (Mirb.) Franco and Taxus baccata L.] in respect of needle size. In case of P. sylvestris, we studied how needle-trace diameter varied among different growing sites and among different shoots within a site, and related that variation to needle morphology and structure. Pinus sylvestris had the greatest diameter of needle traces (mean±SD =233±30 μm) followed by T. baccata (141±19 μm) and P. menziesii (121±30 μm). The smallest needle-trace diameter was in A. sibirica (85±21 μm) and P. abies (80±18 μm). Among species, the needle-trace diameter was strongly correlated with needle length (r =0.93, P <0.05). Within P. sylvestris, the needle-trace diameter was significantly affected by location (P <0.001) and varied significantly among shoots within a location (P <0.001). The shoots of P. sylvestris which had greater average diameter of needle traces, tended to have longer (r =0.36, P <0.05), wider (r =0.55, P <0.05) and heavier (r =0.64, P <0.05) needles with greater stomatal density (r =0.55, P <0.05). Although our results do not allow the use of needle-trace diameter to predict properties of needle structure at the present stage, they nevertheless indicate general trends and point to a need for further studies.