Genet dynamics of a regenerating dwarf bamboo population across heterogeneous light environments in a temperate forest understorey

Abstract

Despite the advantage of plant clonality in patchy environments, studies focusing on genet demography in relation to spatially heterogeneous environments remain scarce. Regeneration of bamboos in forest understoreys after synchronous die‐off provides an opportunity for assessing how they come to proliferate across heterogeneous light environments. In a Japanese forest, we examined genet demography of a population of Sasa kurilensis over a 7‐year period starting 10 years after die‐off, shortly after which some genets began spreading horizontally by rhizomes. The aboveground biomass was estimated, and genets were discriminated in 9‐m2 plots placed under both canopy gaps and closed canopies. Overall, the results suggest that the survival and spread of more productive genets and the spatial expansion of genets into closed canopies underlie the proliferation of S. kurilensis. Compared to canopy gaps, the recovery rate of biomass was much slower under closed canopies for the first 10 years after the die‐off, but became accelerated during the next 7 years. Genet survival was greater for more productive genets (with greater initial number of culms), and the spaces occupied by genets that died were often colonized afterward by clonal growth of surviving genets. The number of genets decreased under canopy gaps due to greater mortality, but increased under closed canopies where greater number of genets colonized clonally from outside the plots than genets died. The colonizing genets were more productive (having larger culms) than those originally germinated within the plots, and the contribution of colonizing genets to the biomass was greater under closed canopies. Our study emphasizes the importance of investigating genet dynamics over relevant spatiotemporal scales to reveal processes underlying the success of clonal plants in heterogeneous habitats.

Spatial genet dynamics of a dwarf bamboo: Clonal expansion into shaded forest understory contributes to regeneration after an episodic die‐off

“…Colonizing genets were identified in one of the following two ways. In the six plots in which genet demography was analyzed, we identified colonizing genets as those that had colonized the plots during the demographic study (see Matsuo et al, 2018 for details). In the newly established plots, we excavated the surface soil (~5 cm) along the border of the plots and identified rhizomes that extended across the border.…”

“…As our results showed that the contribution of clonal expansion was indeed greater but varied among lower-light plots, we next examined whether the contribution was greater in low-light plots nearby canopy gaps from which productive, colonizing genets may have originated. Secondly, although the results of Matsuo et al (2018) infer that colonizing genets are generally more productive (i.e., produce larger culms) than original genets, it remains to be tested whether colonizing genets spread to a greater extent and how they spread in patchy light environments. By closely examining the spatial extent of colonizing and original genets in three closed-canopy plots, we assessed whether colonizing genets with large contributions to biomass spread to a greater extent and whether they spread from surrounding higher-light microsites.…”

Flowering Cycle of Chusquea Mollis L.G. Clark (Magnifoliae, Chusqueinae, Bambusae) in the Venezuelan Andes

“…También es importante tomar en cuenta otros factores que limitan la viabilidad de los frutos, así como el establecimiento y sobrevivencia de plántulas. Entre los principales factores que influyen en el reclutamiento de plántulas está la distribución espacial de los genets adultos, la estructura del sotobosque, la temperatura del aire y del suelo al momento de la dispersión y la radiación incidente que reciben las plántulas durante su fase de establecimiento (Muñoz et al, 2012;De La Fuente & Pacheco, 2017;Matsuo et al, 2018).…”

Forest fire survival in young, denseBetula ermaniistands on soil scarification sites

“…We quantified dwarf bamboo coverage in both plots at 6 and 16 months post fire and found that the forest floor was densely and exclusively re-covered within 16 months post fire (Figures 5 and 6). Dwarf bamboos can dominate the forest floor through asexual reproduction after less severe disturbances (Sasa et al , 1992; Matsuo et al 2018). In the present study plots, the litter was only partially charred on the surface (Table 1).…”

“…In cool-temperate broad-leaved forests, the ground cover is frequently dominated by a dense evergreen understory of dwarf bamboos, Sasa kurilensis (Rupr.) Makino et Shibata (Masaki et al , 1999, Matsuo et al 2018). In northern Japan, dwarf bamboos reproduce vegetatively from their root systems to form a dense cover after less severe disturbances (Goto, 2004), which inhibit seedling emergence and survival of tree species (Taylor and Zisheng, 1992; Noguchi and Yoshida, 2004).…”