Comparison of foliar water use efficiency among 17 provenances of Larix gmelinii in the Mao’ershan area |
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| Authors: | QUAN Xian-Kui WANG Chuan-Kuan |
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| Affiliation: | Center for Ecological Research, Northeast Forestry University, Harbin 150040, China |
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| Abstract: | Aims Investigating tree water use efficiency (WUE) is important for understanding the coupling of carbon and water cycles in terrestrial ecosystems and its responses and adaptation to climatic change. Dahurian larch (Larix gmelinii), the dominant tree species in the Chinese boreal forest, plays an important role in the regional carbon budget. In this study, we measured the foliar WUE and associated physiological parameters of 30-year-old Dahurian larch trees from 17 provenances with divergent climatic conditions in a common garden. Our specific aims were to compare differences in WUE among the provenances and explore whether the observed differences are attributed to potential adaptation or acclimation to local habitats.
Methods We have measured net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and leaf nitrogen concentration (NL) of three replicate trees per provenance from mid June to mid September of 2010. WUE was calculated as the ratio of Pn to Tr. Specific leaf area (SLA) was calculated as one-side projected leaf area divided by the leaf dry mass. The aridity index (AI) of each provenance was calculated as the ratio of mean annual evaporation to mean annual precipitation.
Important findings WUE, Pn, Gs, Tr, SLA and NL all differed significantly among the provenances. WUE showed a significant exponential relationship with Gs. WUE increased significantly with the increase of Gs when the Gs was less than 0.2, and was relatively stable when the Gs was greater than 0.2. WUE was significantly and positively correlated with NL, but negatively with SLA. The degree of these correlations increased with increasing AI values of the tree origins. WUE was negatively correlated with the mean annual temperature and mean annual precipitation of the tree origins, but positively correlated with the AI of the tree origins. Tr and Pn were positively correlated with both mean annual temperature and AI of the tree origins, these results suggest that the trees may adapt to the local climatic conditions of their origins, which results in the significant difference in the needle morphological and physiological properties, and thus WUE among the provenances of Dahurian larch trees. |
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| Keywords: | Larix gmelinii water use efficiency photosynthetic physiology aridity index climate change |
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