We studied regeneration patterns of the four canopy dominants, Abiessachalinensis (Fr. Schm.) Masters, Piceajezoensis (Sieb. et Zucc.) Cam, Piceaglehnii (Fr. Schm.) Masters, and Betulaermanii Cham., of an old-growth (>400 years) boreal coniferous forest in northern Japan. Age and size structure, height growth, and diameter growth of tree populations in a 40 × 40 m plot were analyzed. Seedling establishment was restricted to nurse logs and mounds (98%), where the influence of dwarf bamboo (Sasasenanensis (Franch. et Sav.) Rehd.) was limited. Abiessachalinensis had a high density (10 263/ha) but a high mortality (8.4%/year for saplings, 1.7%/year for canopy trees) and a short canopy residence time. It also showed a more rapid tree-ring width increase after disturbances. Piceaglehnii had a low density (1450/ha) but a low mortality (6.9%/year for saplings, 0.1%/year for canopy trees) and a longer residence time in the canopy. Piceajezoensis had an intermediate density (8206/ha) and its mortality rate for canopy trees (0.9%/year) was lower than that of A. sachalinensis, although its sapling mortality rate (8.1%/year) was similar to that of A. sachalinensis. Betulaermanii had a higher mortality (14.1%/year for saplings, 2.4%/year for canopy trees) than the conifers. On the other hand, B. ermanii had the highest height growth and P. glehnii had the lowest. The mortality and average height growth of saplings showed a trade-off relationship. The trade-off relation in life history strategy may contribute to the coexistence of these species. The proportion of the gap area created in the forest was 1.2–2.4%/year, and a forest turnover time calculated from aboveground volumes was 87–99 years. These values were similar to a weighted mean of the estimated life times of the constituent species, 71 years for A. sachalinensis, 123 years for P. jezoensis, and 49 years for B. ermanii.
Stand structure was studied with special reference to growth and mortality patterns of sapling and understorey trees in a coniferous Picea jezoensis and Abies sachalinensis forest in Taisetsuzan National Park, Hokkaido, northern Japan. Picea jezoensis was dominant in the basal area, while A. sachalinensis was abundant in large numbers in the canopy. Estimated mortalities increased significantly with diameter at breast height (DBH) for both P. jezoensis and A. sachalinensis in the canopy, but the tendency was different between the two species. Piceajezoensis had a lower mortality rate than A. sachalinensis, especially at small DBH classes. The spatial distribution of understorey individuals of A. sachalinensis did not show any significant correlation with the spatial distribution of canopy gaps, but that of P. jezoensis showed a significant correlation. Abies sachalinensis can grow higher than P. jezoensis under suppressed conditions; while P. jezoensis requires canopy gaps for steady height growth. This growth pattern leads to a different waiting height in the understorey (I> 2 m in height and 10 cm in diameter at breast height). Abies sachalinensis waited for an improvement in light conditions at higher strata (max. 7 m), while P. jezoensis waited at lower strata (max. 3 m). The estimated mortality of understorey A. sachalinensis increased with size, while that of understorey P. jezoensis decreased. Therefore, P. jezoensis gives priority to survival while A. sachalinensis gives priority to understorey growth. The difference in the 'waiting pattern' between the two species in the understorey was considered a significant feature for the canopy recruitment process of P. jezoensis and A. sachalinensis.
We investigated the longevity of individual flowers of Corydalis ambigua Cham. et Schlecht. during different periods of pollinator activity and at different temperatures. To measure potential (unpollinated) flower longevity of C. ambigua, this study was conducted at forest islands where pollinator visits were scarce. The longevity of individual flowers of C. ambigua indicated high plasticity. The longevity of unpollinated flowers in natural pollination ranged from 2 to 25 days and continuously decreased with the date of flower opening. The temperature increased as the flowering season progressed. Furthermore, the greenhouse transplanting experiment showed that higher temperatures shorten the life span of flowers. The longevity of pollinated flowers subjected to hand pollination of newly opened flowers was shorter than that of unpollinated flowers in natural pollination regardless of the date of flower opening. These results showed that not only high temperature but also pollination shortens flower longevity. We discuss the role of plasticity in flower longevity for C. ambigua in relation to pollination success and reduction in the maintenance cost of the flowers.
Understory bamboo species are important and influential components of temperate forests in at least several parts of the world. Here we report a study testing the effect of forest fragmentation on the dynamics of the dwarf bamboo Sasa chartacea and on forest herb communities in the Tokachi plain of Hokkaido, Japan. We studied 16 forest fragments of different sizes and small plots established in these fragments to examine the relationship between the abundance of S. chartacea, landscape and environmental conditions, and forest herb communities. Sasa chartacea was more abundant near forest edges and in smaller fragments, suggesting that the species has expanded its local range and increased its abundance in response to forest fragmentation. Edge-related changes in light and soil moisture might have facilitated this range expansion. The species richness of forest herbs was strongly negatively related to the density of S. chartacea. Because much larger variation in species richness was explained by S. chartacea density than distance to the nearest forest edge, the expansion of S. chartacea has likely excluded other understory species by competition. In addition, the density of S. chartacea significantly explained variation in the species composition of forest herbs across plots. Taken together, our results emphasize the key roles of dwarf bamboos in changing plant communities following forest fragmentation.
The recovery process of a Sasa tsuboiana population after a mass flowering and death in 1977 was investigated by 15 years of observation in the Hira Mountains, Kinki district, western Japan. Seed production was high (6600-13 800 seeds m -2 in Sasa plots and 3900 seeds m -2 in a forest plot) but m ), probably because of seed predation by Microtus emergent seedling density was low (14-21 seedlings -2 montebelli occurring between seed shedding and the next spring. The seedling density had decreased further by the next year and the S. tsuboiana population recovered from only a limited number of seedlings. In spite of such a low initial density, the S. tsuboiana population was able to regenerate successfully and attained the previous full stand height in 7-16 years. Miscanthus sinensis invaded and delayed the recovery of S. tsuboiana in one plot, but S. tsuboiana became dominant as it caught up with the height of M. sinensis.Seedling growth patterns, such as frequent tillering, the onset of rhizome extension in the early stage of seedling growth and frequent culm production from rhizomes, played important roles in the successful regeneration of S. tsuboiana.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.