Transport of Airborne Picea schrenkiana Pollen on the Northern Slope of Tianshan Mountains and Its Implication for Paleoenvironmental Reconstruction

 The genus Picea is one of the dominant tree species broadly distributed in subalpine vegetation of temperate, cold temperature, and subtropical climate zones in the Northern Hemisphere. The history of　spruce forests can be a valuable tool for understanding environmental changes, ecological restoration, and human impacts on the environment.

The reconstruction of vegetation dynamics in the past needs the knowledge of modern pollen and vegetation relationship as accurate as possible. Modern Picea pollen studies, which have been conducted in Xinjiang were based on surface soil collection. Studies indicated that Picea pollen disperses extensively and is transported widely. But because of its origin, transportation and deposition of Picea pollen is still unclear.

Contemporary Picea airborne pollen data can help to identify both source areas of pollen transported over long distances and the dominant wind direction that can help the reconstruction of the vegetation history. Moreover, airborne pollen data can also be used to monitor the phenology of the vegetation. Such information can then be applied to identify and interpret possible climatic and environmental changes on a local as well as on a regional scale.

To quantify the airborne pollen grains and establish the pollen season to measure the pollen dispersion and to study the relationship between meteorological parameters in the northern slope of Tianshan Mountains, PAN Yanfang et al. set three Cour airborne pollen traps in Tianchi Weather Station, Fukang Research Station of the Chinese Academy of Sciences and Beishawo Multisphere Obervation and Research Station. Airborne pollen were collected in the three station from July 2001 to July 2006, in which only Picea pollen were analyzed in this study.

The results indicate that Picea pollen disperses extensively and transports widely in the lower atmosphere far away from spruce forest. The airborne Picea pollen dispersal period is mainly concentrated between mid-May and July. In desert area, weekly Picea pollen began to increase and peaked suddenly in concentration. Also annualpollen indices do not decline even when the distance increased was probably related to the strong wind may pick up the deposited pollen grains from the topsoil into the air stream, leading to an increase of pollen concentration in the air that is irrelevant to the normal and natural course of pollen transport and deposition. This, in turn, may lead to erroneous interpretations of the pollen data in the arid region.

This study provided insight into the shift in the Picea pollen season regarding climate change in arid areas. It is recorded that the pollen pollination period starts earlier and the duration became longer. The results also showed that the temperature of May and June was positively correlated with the Picea pollen production. Furthermore, the transport of airborne Picea pollen data is useful for interpreting fossil pollen records from extreme arid regions. The paper was published in Aerobiologia in June 2013, 29(2): 161-173.