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Common tree growth anomalies over the northeastern Tibetan Plateau during the last six centuries: implications for regional moisture change 总被引:1,自引:0,他引:1
JINBAO LI † EDWARD R. COOK ROSANNE D'ARRIGO FAHU CHEN† XIAOHUA GOU† JIANFENG PENG† JIANGUO HUANG‡ 《Global Change Biology》2008,14(9):2096-2107
The world's hydrological cycle is believed to intensify with global warming, yet current climate models have only a limited ability to assess moisture responses at regional scales. Tree-ring records are a valuable source of information for understanding long-term, regional-scale moisture changes, particularly for large regions such as the Tibetan Plateau (TP), where the observational data are short and sparse. Here, we present a new ring-width chronology developed from Qilian Juniper ( Sabina przewalskii ) wood at two sites on the northeastern TP. This chronology, combined with others from the same region, demonstrates that tree growth anomalies are linked to regional late spring to early summer moisture availability. Although late monsoon season precipitation in the study area decreased during recent decades, tree growth continued to increase due to persistent moisture availability in the early monsoon season. Comparison with global sea surface temperatures (SSTs) indicates that early (late) monsoon season precipitation is closely related to tropical Pacific (Indian Ocean) SSTs, suggesting a possible seasonal shift in the dominant moisture source area for monsoonal precipitation over the northeastern TP. It is further shown that there is a very high degree of coherency regarding low-frequency tree growth anomalies over the northeastern TP during the last six centuries. The most prominent drought epoch occurred during ca. 1450–1500, which may have been caused by a significant decrease in the thermal gradient between the Eurasian continent and the tropical oceans. A persistent tree growth increase since the 1880s is coincident with global warming, suggesting an intensified early monsoon season moisture regime in the study area. 相似文献
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MARTIN SCHLIEP GERMÁN CAVIGLIASSO ROSANNE G. QUINNELL ROBERT STRANGER ANTHONY W. D. LARKUM 《Plant, cell & environment》2013,36(3):521-527
We discuss recent advances in chlorophyll research in the context of chlorophyll evolution and conclude that some derivations of the formyl side chain arrangement of the porphyrin ring from that of the Chl a macrocycle can extend the photosynthetic active radiation (PAR) of these molecules, for example, Chl d and Chl f absorb light in the near‐infrared region, up to ~750 nm. Derivations such as this confer a selective advantage in particular niches and may, therefore, be beneficial for photosynthetic organisms thriving in light environments with particular light signatures, such as red‐ and near‐far‐red light‐enriched niches. Modelling of formyl side chain substitutions of Chl a revealed yet unidentified but theoretically possible Chls with a distinct shift of light absorption properties when compared to Chl a. 相似文献
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HOFFMANN ROSANNE; TUFARIELLO JOANN; BISSON MARY A. 《Journal of experimental botany》1989,40(8):875-881
The effect of elevated Na+ concentration on Na+ permeability(PNa) and Na+ influx in the presence of two levels of externaldivalent cations was determined in Chara corallina and freshwater-culturedChara buckellii. When Na+ in the medium was increased from 1.0to 70 mol m3, Na+ influx increased in both species ifCa2+ was low (0.1 mol m3). If Ca2+ was increased to 7.0mol m3 when Na+ was increased, Na+ influx remained atthe low control level in C. corallina, and showed only a temporaryincrease in C. buckellii. Mg2+ was a better substitute for Ca2+in C. buckellii than in C. corallina. Na+ permeability data suggest that when the external Ca2+ concentrationis low, PNa does not increase in the presence of elevated NaCl;the increase in Na+ influx appears to be due to the increasein external Na+ concentration alone. Ca2 + supplementation appearsto decrease PNa whereas supplemental Mg2+ has no effect. Na+ effluxes were computed from previously determined net fluxesand the influxes. It was found that for both species, fluxesin both directions were stimulated in response to all experimentaltreatments, but Na+ influx always exceeded efflux. This resultedin net Na+ accumulation in the vacuoles of both species. The results are discussed with reference to net flux and electrophysiologicaldata obtained previously under identical conditions, as wellas the comparative salinity tolerance of both species and theNa+/divalent cation ratio. Key words: Na+ influx, Na+ tolerance, membrane potential, permeability, Chara 相似文献
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