Yoko Hisamoto

The species biology of bamboos in Japan: from gene to landscape

Bamboos are woody grasses of the family Poaceae, which mainly inhabit tropical and temperate regions. The northern limit of their distribution is east Eurasia (Takeda 1988; Bystriakova et al. 2003). In the Japanese Islands, their natural habitats are mainly grasslands, forest understory, riparian woodlands, mountain ridges, and ravines. The bamboos are often dominants in the plant communities that have been subjected to disturbances. In recent decades, the aggressive invasions of bamboo species into habitats that have experienced human interference have been increasingly relevant for biodiversity and ecosystem services (e.g. Chen et al. 2009; Suzuki & Nakagoshi 2011; Tomimatsu et al. 2011). Bamboos have been the subject of many studies because of their differences from typical woody and herbaceous plants. They have long lifespans with rare “simultaneous” flowering and seeding events in their habitats (Suyama et al. 2010; Abe & Shibata 2012). Their distribution depends on the cold tolerance of their evergreen shoots (Konno 1977; Scurlock et al. 2000). Physiological integrations among ramets support their rhizomatous clonal growth (Li et al. 2000; Saitoh et al. 2002), and density regulations of ramets control their culm population dynamics (Li et al. 1997; Makita 1998). Seasonal leaf photosynthetic activity (Lei & Koike 1998; Gratani et al. 2008) links to matter economy at the community level (Suzuki & Stuefer 1999; Sakai et al. 2006). Subterranean and genet structures reflect the history of intrinsic controls and external pressures on survival (Suyama et al. 2000; Isagi et al. 2004; Miyazaki et al. 2009). Thus, bamboos are studied in many fields, including taxonomy, ecology, grassland sciences, and forest sciences. The 44th Symposium of the Society for Study of Species Biology’s (SSSB, http://www.speciesbiology.org/), “The Species Biology of Bamboos”, was held in December 2012 in conjunction with the Bamboo and Landscape Network (BaLaNET, http://bambooscape.web.fc2.com/), that is, the editors in this issue, and Drs Shigeo Suzuki and Hiroto Kawai, in Takashima City, Shiga Prefecture, western Japan. The present special issue is an outcome of this symposium, which covered multidisciplinary presentations and discussions, especially on recent bamboo biology and impacts of invasion on ecosystem structure and functions. First, Kobayashi (2014) reviews the phylogenetic positions of bamboo groups, and summarizes speciations in the members of the genus Sasa and allies with overlapped but skewed distributions in Japan. His careful long-term morphological and field observations combined with recent genetic analyses result in an improved Sasa group tree and revised genera distribution map, providing valuable evolutional and ecological insights and inspiration on bamboo studies. Second, Suzuki (2014) reports chronological invasion processes of giant bamboo, Phyllostachys pubescens, in western Japan after the 1980s. This most aggressive alien species introduced from the Asian Continent has been naturalized in abandoned rural areas of Japan. His report suggests that expansions of this species observed in many local areas occurred by active clonal growth from the artificially planted small patches in the previous century, resulting in rapid changes of landscapes over Japan. It has been noticed that the development of bamboo thickets induces a decline of biodiversity and inhibits regeneration of other plants (e.g., Kobayashi et al. 1999; Kobayashi & Tada 2010). The remainder of the articles in this special issue focus on the process effects of bamboo invasion and dominance on the ecosystem structure and functions. From a field experiment in a forest of northern Japan, Fukuzawa et al. (2015) demonstrate that a dwarf bamboo Sasa senanensis advances rapidly into the opened stands, and compensate carbon gain and nutrient retention in the disturbed forest ecosystem. Fukushima et al. (2014) found such effects of bamboo dominance in the case of giant bamboo (P. pubescens) that has invaded abandoned coppice forests in western Japan. In these forests, greater biomass allocation into the root systems in the bamboo species plays an important role in ecosystem structure and functions. Shinohara and Otsuki (2015) also Correspondence: Tsuyoshi Kobayashi Email: t-koba@ag.kagawa-u.ac.jp Plant Species Biology (2015) 30, 42–44 doi: 10.1111/1442-1984.12075 bs_bs_banner

Genetic control of altitudinal variation on female reproduction in Abies sachalinensis revealed by a crossing experiment

ABSTRACT The relationship between reproduction and vegetative growth is linked to plants’ life history strategies. Female reproduction often starts earlier in trees growing at high altitudes than those at low altitudes despite their smaller size; moreover, trees growing in a severe environment tend to have a large reproductive biomass after the onset of reproduction. To determine whether these aspects of female reproduction in high-altitude trees are heritable, we analyzed the progeny of four crosses between Abies sachalinensis trees from high altitude (1100–1200 m above sea level [asl]) (H) and low altitude (530 m asl) (L), namely (female × male): L × H, H × L, L × L, and H × H. Progeny of each cross were planted in experimental garden at 230 m asl at the University of Tokyo, Hokkaido Forest in 1986 and in 2011–2014, the number of female cones from 21 trees derived from the four crosses were counted and individual tree sizes were measured. The number of cones was in the order: L × H < L × L < H × L < H × H. Statistical analysis showed that tree size and the proportion of high-altitude genome in both mother and father significantly affected the number of cones produced. Larger trees with higher proportions of the high-altitude genome tended to produce more cones, although the L × H progeny produced fewer cones than the H × L progeny, despite their similar heights and proportions of the high-altitude genome. The growth environment of the maternal parent trees during seed formation might also have influenced the number of cones.