J Plant Ecol ›› 2019, Vol. 12 ›› Issue (2): 292-305.DOI: 10.1093/jpe/rty024

• Research Articles • Previous Articles     Next Articles

Interactions among dwarf bamboo, litter and consumption by small vertebrates place multiple constraints on the establishment of native tree seedlings in a Japanese agricultural landscape

Yoshinori Tokuoka1,*, Kentaro Ohigashi2, Koji Watanabe3, Hiroshi Yamaguchi3, Takahiro Ara3 and Nobukazu Nakagoshi4   

  1. 1 Division of Biodiversity, Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, 3-1-3, Kannondai, Tsukuba-shi, Ibaraki 305-8604, Japan
    2 Division of Informatics and Inventory, Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, 3-1-3, Kannondai, Tsukuba-shi, Ibaraki 305-8604, Japan
    3 Department of Planning and Coordination, Tsukuba Technical Support Center, National Agriculture and Food Research Organization, 3-1-3, Kannondai, Tsukuba-shi, Ibaraki 305-8604, Japan
    4 Graduate School for International Development and Cooperation, Hiroshima University, 1-5-1 Kagamiyama, Higashi-Hiroshima 739-8529, Japan
    *Correspondence address. Division of Biodiversity, Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, 3-1-3, Kannondai, Tsukuba-shi, Ibaraki 305-8604, Japan. Tel.: +81-29-838-8245; Fax: +81-29-838-8199; E-mail: tokuoka@affrc.go.jp
  • Received:2017-10-13 Revised:2018-06-07 Accepted:2018-07-12 Online:2018-07-14 Published:2019-04-01

Abstract:

Aims

Faunal assemblage alterations due to anthropogenic impacts have changed herbivore–vegetation relationships in various ecosystems, but the influences of small vertebrates on revegetation processes remain unclear. In a peri-urban agricultural landscape in eastern Japan that lacks large ungulates but supports small generalist herbivores, fewer native seedlings have become established in thickets dominated by native dwarf bamboo, Pleioblastus chino (Franch. et Sav.) Makino. The mechanisms limiting tree seedling establishment are unknown. Our aim here was to evaluate the influence of interactions among the dwarf bamboo, its litter cover and small vertebrate herbivores on the microsite conditions governing the establishment of native tree seedlings from different successional stages in an old field in temperate Japan.

Methods

First, seedling emergence and survival of seeded Pinus densiflora Siebold et Zucc., Celtis sinensis Pers., Aphananthe aspera (Thunb.) Planch., Quercus serrata Murray, Quercus myrsinifolia Blume and Castanopsis sieboldii (Makino) Hatus. ex T. Yamaz. et Mashiba were observed in a factorial design that accounted for the presence or absence of dwarf bamboo and its litter cover, as well as the exclusion or access of small vertebrate fauna, in 2009 and 2010. To identify small vertebrate herbivores that reduced the emergence or survival of tree seedlings in the first experiment, reseeding experiments using P. densifloraC. sinensisA. aspera and Q. myrsinifolia were conducted by video trapping in 2011 and video and still-camera trapping in 2012.

Important Findings

The abiotic conditions under the dwarf bamboo were lethal to early- to mid-successional P. densifloraC. sinensisA. aspera and Q. serrata but led to better survival—although spindly growth—of late-successional Q. myrsinifolia and C. sieboldii. The main consumers and the plants they found palatable differed between the bamboo thickets and the intervening gaps. Predation by mice appeared to have severely limited the emergence of all species, particularly in the bamboo thickets but occasionally in the gaps, whereas litter cover slightly mitigated this limitation. However, bamboo litter cover reduced the emergence of P. densiflora in the gaps. Chinese bamboo partridge (Bambusicola thoracicus Temminck), an introduced game bird, selectively and severely fed on the cotyledons—and probably seeds—of A. aspera and moderately preyed upon those of P. densiflora in the gaps. Apparent consumption of seedlings in the gaps by the Japanese hare (Lepus brachyurus Temminck) suppressed the growth of all species but apparently did not severely affect emergence and survival. Thus, the net balance of positive and negative interactions at the bamboo thicket scale (i.e. the presence of dominant dwarf bamboo cover or intervening gaps and the herbivore behaviours in these two environments) and at the microsite level (i.e. litter cover) shapes the early establishment patterns of native tree seedlings, and this balance differs among tree seedling species.

Key words: bamboo cover, farmland abandonment, microsite limitation, selective herbivory, Pleioblastus chino