During the Last Glacial Maximum (LGM), pinaceous species such as those in Abies, Tsuga, Picea and Pinus were dominant in Japan (Tsukada, 1983). Although the quality and quantity of plaeoecological data for the LGM has increased throughout Japan, quantitative reconstruction of the LGM vegetation is still in its infancy because of the lack of pollen productivity estimates (PPEs) for those taxa – one of the essential parameters necessary for the Landscape Reconstruction Algorithm (LRA; Sugita, 2007a, b). This study uses the litter-trap method of Saito (Saito and Takeoka,1983, 1985) to obtain PPEs for thirteen species in Pinaceae and Betula characteristic for the LGM vegetation. We use 5-12 traps 50 cm × 50 cm in opening that are placed in each of nearly monospecific stands of those species in various parts of Japan. The number of male flowers produced per ha per year (Fn) is estimated from those collected in traps, and the number of pollen grains in male flowers (PFn) from flower specimens collected just before flowering and fixed in Farmer’s fixative (Ethanol : Acetic acid =3:1) for pollen counting later. PPEs [grains ha^-1 year^-1] are calculated as Fn･PFn. Also, evaluation of the LRA is currently underway in the subalpine forests of the Kita Yatsugatake mountains, using pollen data from the Shirakomaike pond (ca. 7.7 ha) and the Shirakoma mire (ca. 0.1 ha) and the vegetation composition around the sites. Year-to-year variations of pollen production for those species will be measured several more years to increase the reliability of the LRA-based reconstruction.

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Progress of the Cryptomeria japonica pollen front in 2021 was monitored by tracking the first day of pollen release using a Durham sampler at 81 sites and an IS Rotary sampler at eight sites, distributed from Kyushu to Hokkaido in Japan. The results from the Durham sampler showed that by late January, the pollen front had reached the northern parts of western Chugoku on the Sea of Japan, and parts of Tokai that faced the Pacific Ocean. By early February, the front had passed through all of Kyushu and reached parts of Chugoku, parts of Shikoku that faced the Seto Inland Sea, and parts of southern Kinki, Tokai and southern Kanto that faced the Pacific Ocean. By mid-February, the front had passed through central Chugoku, northern Shikoku, almost all of Kinki and Hokuriku, and parts of Tokai, Chubu, southern Kanto and southern Tohoku. By late February, the front had reached the central to northern areas of Tohoku and, unexpectedly, parts of northern Chugoku that faced the Sea of Japan. By early to mid-March, the front had reached the northern parts of Tohoku, although the front had already reached some parts of this area in late February. The front finally reached the eastern and central parts of Hokkaido by late March.

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