Sonoko Watanabe

Clonal structure and flowering traits of a bamboo (Phyllostachys pubescens (Mazel) Ohwi) stand grown from a simultaneous flowering as revealed by AFLP analysis

Although many bamboo species are characterized by simultaneous flowering at long intervals of up to 120 years, few studies have revealed the length of the flowering interval for very‐long‐lived bamboo species by observing the whole life cycle of a single clone. The flowering interval of Phyllostachys pubescens had been determined to be 67 years by means of observation through the entire life cycle from 1912 to 1979. We observed and analysed the clonal structure and flowering traits of a P. pubescens community which had regenerated from seed in 1930 and began to flower in 1997. Although this interval was again 67 years, flowering and nonflowering culms were mixed, and the flowering event lasted three years in the community. AFLP analysis of DNA samples showed distinct genets that originated from the previous flowering event and that each genet had its own flowering time. This is the first report to show that (i) different genets are mixed in a community of a large bamboo species with a leptomorphic rhizome system, and (ii) a community that originated from a single flowering event can have a range of flowering years.

Genetic and reproductive consequences of forest fragmentation for populations of Magnolia obovata

In order to evaluate the consequences of forest fragmentation on populations of Magnolia obovata, we compared genetic diversity and reproductive characteristics at two nearby sites, one conserved and one fragmented. The genetic diversity between adults trees of the different sites was not significantly different. However, saplings in the conserved site showed a significantly higher genetic diversity than both adult trees in the conserved site and saplings in the fragmented sites; this was found to be the result of the larger gene flow into the conserved site. The density of the adult trees was significantly related to all of the reproductive traits analyzed (fertilization of ovules, insect attack to seeds, ovules that developed into seeds and outcrossing at the stage of seeds) at both sites. At both sites, fertilization of ovules and insect attack on seeds were positively correlated to adult tree density while outcrossing rate was negatively correlated to adult tree density. The fertilization of ovules and outcrossing were more dependent on adult tree density in the fragmented site than in the conserved site. The probability of ovules developing into outcrossed seeds showed a negative correlation with adult tree density at both sites, indicating the advantage of low density for this species and possibly implying a resilience to habitat fragmentation. A two-generation-analysis did not identify significant differences between sites in terms of the structure of the pollen pool and the number of pollen donors. Although fragmentation affected reproductive characteristics, the effect on seedling establishment and subsequent survival remains to be determined. Proposals for future studies that will assist in the development of management strategies for forests suffering fragmentation are made.

Evaluation of the Environmental DNA Method for Estimating Distribution and Biomass of Submerged Aquatic Plants.

The environmental DNA (eDNA) method has increasingly been recognized as a powerful tool for monitoring aquatic animal species; however, its application for monitoring aquatic plants is limited. To evaluate eDNA analysis for estimating the distribution of aquatic plants, we compared its estimated distributions with eDNA analysis, visual observation, and past distribution records for the submerged species Hydrilla verticillata. Moreover, we conducted aquarium experiments using H. verticillata and Egeria densa and analyzed the relationships between eDNA concentrations and plant biomass to investigate the potential for biomass estimation. The occurrences estimated by eDNA analysis closely corresponded to past distribution records, and eDNA detections were more frequent than visual observations, indicating that the method is potentially more sensitive. The results of the aquarium experiments showed a positive relationship between plant biomass and eDNA concentration; however, the relationship was not always significant. The eDNA concentration peaked within three days of the start of the experiment in most cases, suggesting that plants do not release constant amounts of DNA. These results showed that eDNA analysis can be used for distribution surveys, and has the potential to estimate the biomass of aquatic plants.

Microsatellite Markers for Nuphar japonica (Nymphaeaceae), An Aquatic Plant in the Agricultural Ecosystem of Japan

Premise of the study: Nuphar species (Nymphaeaceae) are representative aquatic plants in irrigation ponds in Japanese agricultural ecosystems. We developed 15 polymorphic microsatellite markers for N. japonica and confirmed their utility for its close relatives N. oguraensis var. akiensis and N. ×saijoensis, which originated from natural hybridization between N. japonica and N. oguraensis. Methods and Results: Genetic variation was characterized in 15 polymorphic loci in three populations of N. japonica. The average number of alleles per locus was 3.47 (range = 2–9; n = 32), and the average expected heterozygosity per locus was 0.84 (range = 0.5–1.0); 11 loci were amplified in N. oguraensis var. akiensis and 15 in N. ×saijoensis. Conclusions: The polymorphic microsatellite markers developed in this study will be useful for investigating the levels of genetic diversity within remnant populations of Nuphar taxa and could provide a valuable tool for conservation genetics of these taxa.

Forest Ownership Patterns Impacting on Landscape Structure of Vegetation in a Mountainous Farm Village, Western Japan

Forest management is defined mainly by the pattern of forest ownership. Thus, it is important to examine the relationships between the landscape structure of forest vegetation and the forest ownership patterns in order to understand the realities of “human impact” on cultural landscapes and ecosystems. Our study area was the mountain farm village of Hiroshima Prefecture, western Japan. These forests are owned and managed by the public, communal, or private sectors. The data set was prepared by overlapping the vegetation map data and the cadastral map data using GIS. The vegetation map was created by using ortho-rectified aerial digital photographs, and the types of vegetation were classified based on physiognomy. The cadastral map data were classified according to the ownership patterns. In the overlapping of the vegetation and cadastral maps, the boundaries between vegetation and ownership frequently conformed in the case of pine or artificial coniferous forests. Characteristic combinations of vegetation type and ownership patterns, such as pine forest and foundation or PFC and artificial coniferous forest, were also verified in terms of the proportion of vegetation type in each ownership pattern. The results suggest that the landscape patterns of strongly disturbed or commercial forests tend to be influenced by forest ownership patterns at the physiognomy level.

Isolation and characterization of microsatellite loci for the endangered wetland plant Adenophora palustris (Campanulaceae).

Premise of the study: Adenophora palustris (Campanulaceae) is an endangered wetland plant species in Japan. Although it is widely distributed in East Asia, only six extant populations are known in Japan, with fewer than 1000 individuals in total. We developed 15 microsatellite markers for this species and confirmed their utility for the closely related species A. triphylla var. japonica. Methods and Results: Ten polymorphic loci were characterized for genetic variation within three populations of A. palustris. The number of alleles per locus ranged from four to 15, with an average of 9.3; the expected heterozygosity ranged from 0.48 to 0.89, with an average of 0.74. Nine loci were successfully amplified in A. triphylla var. japonica, and three of these loci showed polymorphism. Conclusions: These markers are useful for investigating genetic diversity and gene flow within and among remnant populations of A. palustris in Japan, and the results will provide crucial information for conservation.